Title: Data storage device for fast multiple file write operations
Abstract: A data storage device comprising a computer useable medium having computer readable program code disposed therein for writing information on a data storage medium using fast multiple file write operations. A data storage and retrieval system comprising one or more of Applicants' data storage devices. Computer program products embodied as program code stored in Applicants' storage device.
Patent Number: 6,857,044 Issued on 02/15/2005 to Beeston, et al.
| Inventors:
|
Beeston; Ralph Thomas (Tucson, AZ);
Dahman; Kirby Grant (Tucson, AZ);
Grunow; Christopher Paul (Tucson, AZ);
Lyman; Joel Kenneth (Tucson, AZ)
|
| Assignee:
|
International Business Machines Corporation (Armonk, NY)
|
| Appl. No.:
|
977467 |
| Filed:
|
October 15, 2001 |
| Current U.S. Class: |
711/111; 360/49; 360/69; 360/71; 360/72.1; 707/3; 711/112; 711/154 |
| Intern'l Class: |
G06F 012//04 |
| Field of Search: |
360/49,69,71,72,1
707/3,31
711/111,112,4
1/154
|
References Cited [Referenced By]
U.S. Patent Documents
| 3603937 | Sep., 1971 | Loizides et al. | 707/101.
|
| 3984814 | Oct., 1976 | Bailey et al. | 714/16.
|
| 4435762 | Mar., 1984 | Milligan et al. | 710/6.
|
| 5485321 | Jan., 1996 | Leonhardt et al. | 360/48.
|
| 5546557 | Aug., 1996 | Allen et al. | 711/111.
|
| 5586280 | Dec., 1996 | Simms | 711/4.
|
| 5969893 | Oct., 1999 | Basham et al. | 360/49.
|
| 6070224 | May., 2000 | LeCrone et al. | 711/112.
|
| 6124993 | Sep., 2000 | Hallamasek | 360/48.
|
| 6154852 | Nov., 2000 | Amundson et al. | 714/5.
|
| 6173359 | Jan., 2001 | Carlson et al. | 711/111.
|
| 6341329 | Jan., 2002 | LeCrone et al. | 711/112.
|
| 6674599 | Jan., 2004 | Rae et al. | 360/72.
|
Other References
IBM, DFSMS/MVS Version 1 Release 4, GC26-4900-05, General Information,
1980, pp. 1-167.
|
Primary Examiner: Nguyen; T.
Attorney, Agent or Firm: Regelman; Dale F.
Claims
We claim:
1. A data storage device comprising a computer useable medium having
computer readable program code disposed therein for recording information
on a data storage medium, the computer readable program code comprising a
series of computer readable program steps to effect:
receiving a first command to record first information on said data storage
medium;
receiving said first information, wherein said first information comprises
a first header label group, first data, a first trailer label group;
moving said data storage medium in a first direction;
recording said first information beginning at a first time on said moving
data storage medium;
receiving a first deferred conditional write tape mark command;
setting at a second time a first deferred conditional tape mark indicator;
writing said first header label group to said moving data storage medium;
writing a first tape mark adjacent said first header label group;
writing said first data adjacent said first tape mark;
writing a second tape mark adjacent said first data;
writing said first trailer label group adjacent said second tape mark;
writing a third tape mark adjacent said first trailer label group;
specifying a deferred conditional tape mark indicator time interval; and
writing a third tape mark adjacent said first trailer label group:
specifying a deferred conditional tape mark indicator time interval; and
maintaining said first deferred conditional tape mark indicator during said
deferred conditional tape mark indicator time interval.
2. The data storage device of claim 1, wherein said deferred conditional
tape mark indicator time interval is between about 5 seconds and about 20
seconds.
3. The data storage device of claim 2, wherein said deferred conditional
tape mark indicator time interval is about 10 seconds.
4. The data storage device of claim 1, wherein said computer readable
program code further comprises a series of computer readable program steps
to effect:
receiving a second command at a third time to record second information on
said data storage medium, wherein the time interval between said second
time and said third time is less than said deferred conditional tape mark
indicator time interval;
receiving said second information;
resetting said first conditional deferred tape mark indicator;
moving said data storage medium in a first direction;
recording said second information on said moving data storage medium;
receiving a second deferred conditional write tape mark command;
setting a second deferred conditional tape mark indicator at a fourth time;
moving said data storage medium only in said first direction during the
time interval between said first time and said fourth time.
5. The data storage device of claim 4, wherein said second information
comprises:
a second header label group;
second data; and
a second trailer label group.
6. The data storage device of claim 5, wherein said computer readable
program code further comprises a series of computer readable program steps
to effect:
writing said second header label group to said moving data storage medium
adjacent said third tape mark;
writing a fourth tape mark to said moving data storage medium adjacent said
second header label group;
writing said second data to said moving data storage medium adjacent said
fourth tape mark;
writing a fifth tape mark to said moving data storage medium adjacent said
second data;
writing said second trailer label group to said moving data storage medium
adjacent said fifth tape mark; and
writing a sixth tape mark to said moving data storage medium adjacent said
second trailer label group.
7. The data storage device of claim 1, wherein said computer readable
program code further comprises a series of computer readable program steps
to effect:
receiving a second command, wherein said second command causes motion of
said data storage medium in a second direction or causes synchronization
of said data storage medium;
resetting said first deferred conditional tape mark indicator;
disposing a double tape mark on said data storage medium by writing a
fourth tape mark adjacent said third tape mark;
moving said data storage medium in a second direction;
positioning said read/write head between said third tape mark and said
fourth tape mark.
8. The data storage device of claim 7, wherein said computer readable
program code further comprises a series of computer readable program steps
to effect:
determining if said double tape mark was successfully written to said data
storage medium;
determining if said read/write head was successfully positioned between
said third tape mark and said fourth tape mark.
9. The data storage device of claim 8, wherein said double tape mark was
not successfully written to said data storage medium, and wherein said
read/write head was successfully repositioned between said third tape mark
and said fourth tape mark, wherein said computer readable program code
further comprises a series of computer readable program steps to effect
indicating an UNWRITTEN DEFERRED TAPE MARK error message.
10. The data storage device of claim 8, wherein said double tape mark was
successfully written to said data storage medium, and wherein said
read/write head was not successfully repositioned between said third tape
mark and said fourth tape mark, wherein said computer readable program
code further comprises a series of computer readable program steps to
effect indicating a DATA CHECK/LOST POSITIONING error message.
11. The data storage device of claim 8, wherein said double tape mark was
not successfully written to said data storage medium, and wherein said
read/write head was not successfully repositioned between said third tape
mark and said fourth tape mark, wherein said computer readable program
code further comprises a series of computer readable program steps to
effect:
indicating a DATA CHECK/LOST POSITIONING error message; and
indicating an UNWRITTEN DEFERRED TAPE MARK error message.
12. A data storage and retrieval system comprising a data storage device, a
data storage medium removeably disposed in said data storage device. and a
host computer which provides first information to said data storage
device, wherein said data storage device comprises a computer useable
medium having computer readable program code disposed therein for
recording information on a data storage medium storage medium, the
computer readable program code comprising a series of computer readable
program steps to effect:
receiving a first command to record first information on said data storage
medium;
receiving said first information, wherein said first information comprises
a first header label group, first data, and a first trailer label group;
moving said data storage medium in a first direction;
recording said first information on said moving data storage medium
beginning at a first time;
receiving a first deferred conditional write tape mark command;
setting a first deferred conditional tape mark indicator at a second time;
writing said first header label group to said moving data storage medium;
writing a first tape mark adjacent said first header label group;
writing said first data adjacent said first tape mark;
writing a second tape mark adjacent said first data;
writing said first trailer label group adjacent said second tape mark; and
writing a third tape mark adjacent said first trailer label group;
specifying a deferred conditional tape mark indicator time interval; and
maintaining said first deferred conditional tape mark indicator during said
deferred conditional tape mark indicator time interval.
13. The data storage and retrieval system of claim 12, wherein said
deferred conditional tape mark indicator time interval is between about 5
seconds and about 20 seconds.
14. The data storage and retrieval system of claim 13, wherein said
deferred conditional tape mark indicator time interval is about 10
seconds.
15. The data storage and retrieval system of claim 12, wherein said
computer readable program code further comprises a series of computer
readable program steps to effect:
receiving a second command at a third time to record second information on
said data storage medium, wherein the time interval between said second
time and said third time is less than said deferred conditional tape mark
indicator time interval;
receiving said second information from said host computer;
resetting said first conditional deferred tape mark indicator;
moving said data storage medium in said second direction;
recording said second information on said moving data storage medium;
receiving a second deferred conditional write tape mark command;
setting a second deferred conditional tape mark indicator at a fourth time;
wherein said data storage medium is moved only in said first direction
during the time interval between said first time and said fourth time.
16. The data storage and retrieval system of claim 15, wherein said second
information comprises:
a second header label group;
second data; and
a second trailer label group.
17. The data storage and retrieval system of claim 16, wherein said
computer readable program code further comprises a series of computer
readable program steps to effect:
writing said second header label group to said moving data storage medium
adjacent said third tape mark;
writing a fourth tape mark to said moving data storage medium adjacent said
second header label group;
writing said second data to said moving data storage medium adjacent said
fourth tape mark;
writing a fifth tape mark to said moving data storage medium adjacent said
second data;
writing said second trailer label group to said moving data storage medium
adjacent said fifth tape mark; and
writing a sixth tape mark to said moving data storage medium adjacent said
second trailer label group.
18. The data storage and retrieval system of claim 12, wherein said
computer readable program code further comprises a series of computer
readable program steps to effect:
receiving a second command, wherein said second command causes motion of
said data storage medium in a second direction or causes synchronization
of said data storage medium;
resetting said first deferred conditional tape mark indicator;
disposing a double tape mark on said data storage medium by writing a
fourth tape mark adjacent said third tape mark;
moving said data storage medium in a second direction;
positioning said read/write head between said third tape mark and said
fourth tape mark.
19. The data storage and retrieval system of claim 18, wherein said
computer readable program code further comprises a series of computer
readable program steps to effect:
determining if said double tape mark was successfully written to said data
storage medium;
determining if said read/write head was successfully positioned between
said third tape mark and said fourth tape mark.
20. The data storage and retrieval system of claim 19, wherein said double
tape mark was not successfully written to said data storage medium, and
wherein said read/write head was successfully repositioned between said
third tape mark and said fourth tape mark, wherein said computer readable
program code further comprises a series of computer readable program steps
to effect indicating an UNWRITTEN DEFERRED TAPE MARK error message.
21. The data storage and retrieval system of claim 19, wherein said double
tape mark was successfully written to said data storage medium, and
wherein said read/write head was not successfully repositioned between
said third tape mark and said fourth tape mark, wherein said computer
readable program code further comprises a series of computer readable
program steps to effect indicating a DATA CHECK/LOST POSITIONING error
message.
22. The data storage and retrieval system of claim 19, wherein said double
tape mark was not successfully written to said data storage medium, and
wherein said read/write head was not successfully repositioned between
said third tape mark and said fourth tape mark, wherein said computer
readable program code further comprises a series of computer readable
program steps to effect:
indicating a DATA CHECK/LOST POSITIONING error message; and
indicating an UNWRITTEN DEFERRED TAPE MARK error message.
23. A computer program product usable with a programmable computer
processor having computer readable program code embodied therein for
disposing information on a data storage medium using a data storage device
comprising a read/write head, comprising:
computer readable program code which causes said programmable computer
processor to receive a first command to record first information on said
data storage medium;
computer readable program code which causes said programmable computer
processor to receive said first information, wherein said first
information comprises a first header label group, first data, and a first
trailer label group;
computer readable program code which causes said programmable computer
processor to move said data storage medium in a first direction;
computer readable program code which causes said programmable computer
processor to record said first information on said moving data storage
medium beginning at a first time;
computer readable program code which causes said programmable computer
processor to receive a first deferred conditional write tape mark command;
computer readable program code which causes said programmable computer
processor to set a first deferred conditional tape mark indicator at a
second time;
computer readable program code which causes said programmable computer
processor to write said first header label group to said moving data
storage medium;
computer readable program code which causes said programmable computer
processor to write a first tape mark adjacent said first header label
group;
computer readable program code which causes said programmable computer
processor to write said first data adjacent said first tape mark;
computer readable program code which causes said programmable computer
processor to write a second tape mark adjacent said first data;
computer readable program code which causes said programmable computer
processor to write said first trailer label group adjacent said second
tape mark;
computer readable program code which causes said programmable computer
processor to write a third tape mark adjacent said first trailer label
group;
computer readable program code which causes said programmable computer
processor to specify a deferred conditional tape mark indicator time
interval; and
computer readable program code which causes said programmable computer
processor to maintain said first deferred conditional tape mark indicator
during said deferred conditional tape mark indicator time interval.
24. The computer program product of claim 23, wherein said deferred
conditional tape mark indicator time interval is between about 5 seconds
and about 20 seconds.
25. The computer program product of claim 24, wherein said deferred
conditional tape mark indicator time interval is about 10 seconds.
26. The computer program product of claim 23, further comprising:
computer readable program code which causes said programmable computer
processor to receive a second command at a third time to record second
information on said data storage medium, wherein the time interval between
said second time and said third time is less than said deferred
conditional tape mark indicator time interval;
computer readable program code which causes said programmable computer
processor to receive said second information;
computer readable program code which causes said programmable computer
processor to reset said first conditional deferred tape mark indicator;
computer readable program code which causes said programmable computer
processor to move said data storage medium in said first direction;
computer readable program code which causes said programmable computer
processor to record said second information on said moving data storage
medium;
computer readable program code which causes said programmable computer
processor to receive a second deferred conditional write tape mark
command;
computer readable program code which causes said programmable computer
processor to set a second deferred conditional tape mark indicator at a
fourth time;
computer readable program code which causes said programmable computer
processor to move said data storage medium only in said first direction
during the time interval between said first time and said fourth time.
27. The computer program product of claim 26, wherein said second
information comprises:
a second header label group;
second data; and
a second trailer label group.
28. The computer program product of claim 27, further comprising:
computer readable program code which causes said programmable computer
processor to write said second header label group to said moving data
storage medium adjacent said third tape mark;
computer readable program code which causes said programmable computer
processor to write a fourth tape mark to said moving data storage medium
adjacent said second header label group;
computer readable program code which causes said programmable computer
processor to write said second data to said moving data storage medium
adjacent said fourth tape mark;
computer readable program code which causes said programmable computer
processor to write a fifth tape mark to said moving data storage medium
adjacent said second data;
computer readable program code which causes said programmable computer
processor to write said second trailer label group to said moving data
storage medium adjacent said fifth tape mark; and
computer readable program code which causes said programmable computer
processor to write a sixth tape mark to said moving data storage medium
adjacent said second trailer label group.
29. The computer program product of claim 26, further comprising:
computer readable program code which causes said programmable computer
processor to receive a second command, wherein said second command causes
motion of said data storage medium in a second direction or causes
synchronization of said data storage medium;
computer readable program code which causes said programmable computer
processor to reset said first deferred conditional tape mark indicator;
computer readable program code which causes said programmable computer
processor to dispose a double tape mark on said data storage medium by
writing a fourth tape mark adjacent said third tape mark;
computer readable program code which causes said programmable computer
processor to move said data storage medium in a second direction;
computer readable program code which causes said programmable computer
processor to position said read/write head between said third tape mark
and said fourth tape mark.
30. The computer program product of claim 29, further comprising:
computer readable program code which causes said programmable computer
processor to determine if said double tape mark was successfully written
to said data storage medium; and
computer readable program code which causes said programmable computer
processor to determine if said read/write head was successfully positioned
between said third tape mark and said fourth tape mark.
31. The computer program product of claim 30, wherein said double tape mark
was not successfully written to said data storage medium, and wherein said
read/write head was successfully repositioned between said third tape mark
and said fourth tape mark, further comprising computer readable program
code which causes said programmable computer processor to a series of
computer readable program steps to indicate an UNWRITTEN DEFERRED TAPE
MARK error message.
32. The computer program product of claim 30, wherein said double tape mark
was successfully written to said data storage medium, and wherein said
read/write head was not successfully repositioned between said third tape
mark and said fourth tape mark, further comprising computer readable
program code which causes said programmable computer processor to a series
of computer readable program steps to indicate a DATA CHECK/LOST
POSITIONING error message.
33. The computer program product of claim 30, wherein said double tape mark
was not successfully written to said data storage medium, and wherein said
read/write head was not successfully repositioned between said third tape
mark and said fourth tape mark, further comprising:
computer readable program code which causes said programmable computer
processor to indicate a DATA CHECK/LOST POSITIONING error message; and
computer readable program code which causes said programmable computer
processor to indicate an UNWRITTEN DEFERRED TAPE MARK error message.
34. A method to dispose information on a data storage medium using a data
storage device, comprising the steps of:
providing a first command instructing said data storage device to record
first information on said data storage medium;
providing said first information to said data storage device, wherein said
first information comprises a first header label group, first data, and a
first trailer label group;
disposing said data storage medium in said data storage device;
moving said data storage medium in a first direction;
recording said first information beginning at a first time on said moving
data storage medium;
issuing a first deferred conditional write tape command;
setting at a second time a first deferred conditional tape mark indicator;
writing said first header label group to said moving data storage medium;
writing a first tape mark adjacent said first header label group;
writing said first data adjacent said first tape mark;
writing a second tape mark adjacent said first data;
writing said first trailer label group adjacent said second tape mark;
writing a third tape mark adjacent said first trailer label group;
specifying a deferred conditional tape mark indicator time interval;
maintaining said first deferred conditional tape mark indicator during said
deferred conditional tape mark indicator time interval.
35. The method of claim 34, wherein said deferred conditional tape mark
indicator time interval is between about 5 seconds and about 20 seconds.
36. The method of claim 35, wherein said deferred conditional tape mark
indicator time interval is about 10 seconds.
37. The method of claim 34, further comprising the steps of:
providing a second command at a third time instructing said data storage
device to record second information on said data storage medium, wherein
the time interval between said second time and said third time is less
than said deferred conditional tape mark indicator time interval;
providing said second information to said data storage device;
resetting said first conditional deferred tape mark indicator;
recording said second information on said moving data storage medium;
issuing a second deferred conditional write tape mark command;
setting a second deferred conditional tape mark indicator at a fourth time;
moving said data storage medium only in said first direction during the
time interval between said first time and said fourth time.
38. The method of claim 37, wherein said second information comprises:
a second header label group;
second data; and
a second trailer label group.
39. The method of claim 38, further comprising the steps of:
writing said second header label group to said moving data storage medium
adjacent said third tape mark;
writing a fourth tape mark to said moving data storage medium adjacent said
second header label group;
writing said second data to said moving data storage medium adjacent said
fourth tape mark;
writing a fifth tape mark to said moving data storage medium adjacent said
second data;
writing said second trailer label group to said moving data storage medium
adjacent said fifth tape mark; and
writing a sixth tape mark to said moving data storage medium adjacent said
second trailer label group.
40. The method of claim 34, wherein said data storage device comprises a
read/write head, further comprising the steps of:
providing a second command to said data storage drive, wherein said second
command causes motion or synchronization of said data storage medium;
resetting said first deferred conditional tape mark indicator;
disposing a double tape mark on said data storage medium by writing a
fourth tape mark adjacent said third tape mark;
moving said data storage medium in a second direction;
repositioning said read/write head between said third tape mark and said
fourth tape mark.
41. The method of claim 40, further comprising the steps of:
determining if said double tape mark was successfully written to said tape;
determining if said read/write head was successfully positioned between
said third tape mark and said fourth tape mark.
42. The method of claim 41, wherein said double tape mark was not
successfully written to said tape, and wherein said read/write head was
successfully repositioned between said third tape mark and said fourth
tape mark, said method further comprising the step of indicating an
UNWRITTEN DEFERRED TAPE MARK error message.
43. The method of claim 41, wherein said double tape mark was successfully
written to said tape, and wherein said read/write head was not
successfully repositioned between said third tape mark and said fourth
tape mark, said method further comprising the step of indicating a DATA
CHECK/LOST POSITIONING error message.
44. The method of claim 41, wherein said double tape mark was not
successfully written to said tape, and wherein said read/write head was
not successfully repositioned between said third tape mark and said fourth
tape mark, said method further comprising the steps of:
indicating a DATA CHECK/LOST POSITIONING error message; and
indicating an UNWRITTEN DEFERRED TAPE MARK error message.
Description
FIELD OF THE INVENTION
Applicant's invention relates to a data storage device for fast multiple
file write operations.
BACKGROUND OF THE INVENTION
Automated media storage libraries are known for providing cost effective
access to large quantities of stored media. Generally, media storage
libraries include a large number of storage slots in which are stored data
storage media. The portable data storage media are typically housed in a
portable container, such as a tape cartridge, an optical cartridge, and
the like. One (or more) accessors typically access the data storage media
from the storage slots and deliver the accessed media to a data storage
drive for reading and/or writing data on the accessed media. Suitable
electronics operate the accessor(s) and operate the data storage drive(s)
to transmit to, and/or to receive data from, an attached on-line host
computer system.
In a conventional automated media storage library, the storage slots are
arranged in a planar orthogonal arrangement forming a "wall" of storage
slots for holding data storage media. The plane may be a flat plane, or
may be a cylindrical plane. To double the storage capacity, two "walls" of
storage slots may be provided on either side of the accessor.
A number of different companies manufacture automated media storage
libraries today, each model displaying various different features. One
example is the IBM 3494 Media Storage Library. Some of the automated media
storage libraries have dual or multiple accessors to provide a level of
redundancy and/or improved performance.
What is needed, however, is a data management system, method, and apparatus
and method to expedite the recording of information provided by a host
computer onto a data storage medium, particularly where that information
comprises a plurality of individual files.
SUMMARY OF THE INVENTION
Applicants' invention includes a method to dispose information on a
sequential medium, such as a tape, using a data storage device.
Applicants' method includes the steps of providing a first command
instructing the data storage device to record information on a designated
data storage medium, such as a magnetic tape, providing that information
to the data storage device, removeably disposing that designated data
storage medium in the data storage device, moving that data storage medium
in a first direction, recording the information on the moving data storage
medium, issuing a deferred conditional write tape mark command, and
setting a deferred conditional tape mark indicator.
Applicants' invention further includes a data storage device which includes
a computer useable medium having computer readable program code disposed
therein for disposing information on a data storage medium removeably
disposed in that data storage device. Applicants' invention further
includes a data storage and retrieval system comprising a computer useable
medium having computer readable program code disposed therein for
disposing information on a data storage medium using a data storage
device, wherein that data storage and retrieval system comprises a library
controller, at least one data storage drive, at least one portable data
storage medium, and at least one host computer which provides information
to Applicants' data storage device.
Applicants' invention further includes a computer program product usable
with a programmable computer processor having computer readable program
code embodied therein for disposing information on a tape medium using
Applicants' data storage device. Applicants' invention further includes a
computer program product usable with a programmable computer processor
having computer readable program code embodied therein for disposing
information on a tape medium using a data storage device disposed in
Applicants' data storage and retrieval system.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be better understood from a reading of the following
detailed description taken in conjunction with the drawings in which like
reference designators are used to designate like elements, and in which:
FIG. 1 is a perspective view of a first embodiment of Applicants' data
storage and retrieval system;
FIG. 2A is a block diagram of a controller disposed in Applicants' data
storage device;
FIG. 2B is a block diagram of a controller disposed in Applicants' data
storage and retrieval system;
FIG. 3 is block diagram showing the components of Applicants' data storage
and retrieval system;
FIG. 4 is a perspective view of a second embodiment of Applicants' data
storage and retrieval system;
FIG. 5 is a block diagram showing the disposition of information disposed
on a data storage tape medium;
FIG. 6A is a block diagram showing certain steps of a prior art method to
write information to a data storage tape medium;
FIG. 6B is a block diagram showing certain steps of a prior art method to
write information to a data storage tape medium;
FIG. 6C is a block diagram showing certain steps of a prior art method to
write information to a data storage tape medium;
FIG. 6D is a block diagram showing certain steps of a prior art method to
write information to a data storage tape medium;
FIG. 6E graphically depicts the time required to write information to a
data storage tape medium using prior art methods;
FIG. 7A is a block diagram showing certain steps of Applicants' method to
write information to a data storage tape medium;
FIG. 7B is a block diagram showing certain steps of Applicants' method to
write information to a data storage tape medium;
FIG. 7C is a block diagram showing certain steps of Applicants' method to
write information to a data storage tape medium;
FIG. 7D is a block diagram showing certain steps of Applicants' method to
write information to a data storage tape medium;
FIG. 7E is a block diagram showing certain steps of Applicants' method to
write information to a data storage tape medium;
FIG. 8 is a flowchart summarizing the initial steps in Applicants' method
to write information to a data storage tape medium;
FIG. 9 is a flowchart summarizing the steps of prior art methods to write
information to a data storage tape medium;
FIG. 10 is a flowchart summarizing additional steps in Applicants' method
to write information to a data storage tape medium; and
FIG. 11 is a flowchart summarizing additional steps in Applicants' method
to write information to a data storage tape medium.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to the illustrations, like numerals correspond to like parts
depicted in the figures. The invention will be described as embodied in an
automated data storage and retrieval subsystem for use in a data
processing environment. The following description of Applicant's method to
record information to a movable tape medium, or to a movable tape medium
disposed within a portable data storage cartridge is not meant, however,
to limit Applicant's invention to either data storage and retrieval
systems, or to magnetic tape applications, as the invention herein can be
applied to data storage media in general.
FIG. 3 illustrates the hardware and software environment in which preferred
embodiments of the present invention are implemented. Host computer 390
includes, among other programs, Applicants' hierarchical storage
management (HSM) program 310. Host computer 390 comprises one or more
mainframe computers, one or more personal computers, and/or combinations
thereof.
Information is transferred between the host system 390 and secondary
storage devices managed by a data storage and retrieval system, such as
tape subsystem 320, via communication link 350. Communication link 350
comprises a serial interconnection, such as an RS-232 cable or an RS-432
cable, an ethernet interconnection, a SCSI interconnection, a Fibre
Channel interconnection, an ESCON interconnection, a FICON
interconnection, a Local Area Network (LAN), a private Wide Area Network
(WAN), a public wide area network, Storage Area Network (SAN),
Transmission Control Protocol/Internet Protocol (TCP/IP), the Internet,
and combinations thereof.
In the embodiment shown in FIG. 3, tape subsystem 320 includes tape drives
330 and 340. In other embodiments of Applicants' data storage and
retrieval system, tape subsystem 320 includes a single data storage drive.
In alternative embodiments, Applicants' data storage and retrieval system
320 includes more than two data storage drives.
A plurality of portable data storage media 360 are stored within
Applicants' data storage and retrieval system. In certain embodiments,
plurality of data storage media 360 are each housed in a portable data
storage cartridge 370, such as plurality of portable tape cartridges 370
(not shown in FIG. 3). Each of such portable data storage cartridges may
be inserted in one of tape drives, and thereafter accessed by the tape
subsystem 320. In alternative embodiments, alternative storage media may
be substituted for the tape cartridges 370. Any type of sequential storage
media supporting a sequential access command architecture could be used.
The tape subsystem 320 further includes program logic to manage tape drives
330 and 340, and plurality of tape cartridges 370. In alternative
embodiments, tape subsystem 330 and host system 390 may be located on a
single computer machine.
Host system 390 comprises a computer system, such as a mainframe, personal
computer, workstation, etc., including an operating system such as
Windows, AIX, Unix, MVS, etc. (Windows is a registered trademark of
Microsoft Corporation; AIX is a registered trademark and MVS is a
trademark of IBM Corporation; and UNIX is a registered trademark in the
United States and other countries licensed exclusively through The Open
Group.) The HSM program 310 in the host system 390 may include the
functionality of HSM type programs known in the art that manage the
transfer of data to a tape library, such as the IBM DFSMS implemented in
the IBM MVS operating system.
The IBM DFSMS software is described in "DFSMS/MVS V1R4 General
Information," IBM document no. GC26-4900-05, published by IBM (Copyright
1997, IBM), which publication is incorporated herein by reference in its
entirety. In addition to including known HSM functions, such as recall and
migration, the HSM program 310 would further include additional program
instructions to perform the operations of the preferred embodiments of the
present invention. The HSM program 310 may be implemented within the
operating system of the host system 390 or as a separate, installed
application program.
The tape subsystem 320 comprises a computer system, and manages a plurality
of tape drives and tape cartridges. The tape drives 330 and 340 may be any
suitable tape drives known in the art, e.g., the Magstar 3590 tape drives.
Tape cartridges 370 may be any suitable tape cartridge device known in the
art, (Magstar is a registered trademark of IBM Corporation) such as ECCST,
Magstar, IBM 3420, 3480, 3490E, 3590 tape cartridges, etc. The tape
subsystem 320 may be a manual tape library in which the user must manually
mount tape cartridges 370 into the tape drives 330/340, or an automated
tape library (ATL) in which a robotic arm mounts tape cartridges 370 in
the library into the tape drives 330/340.
For example referring now to FIG. 1, automated data storage and retrieval
system 100 is shown having a first wall of storage slots 102 and a second
wall of storage slots 104. Portable data storage cartridges, such as tape
cartridges 370, are individually stored in these storage slots.
Data storage and retrieval system 100 includes one or more accessors, such
as accessors 110 and 120. An accessor is a robotic device which accesses
portable data storage media from first storage wall 102 or second storage
wall 104, delivers that accessed media to data storage devices 130/140 for
reading and/or writing data thereon, and returns the media to the proper
storage slot.
Referring now to FIG. 2A, data storage device 130 includes device
controller 232. Controller 232 includes microprocessor 234 in
communication with memory 236. In certain embodiments, microprocessor 234
communicates with memory 236 via communication link 235. In other
embodiments, memory 236 is integral to microprocessor 234. Device
microcode 238 is stored in memory 236. Device microcode comprises a
computer program product which controls the operation of a data storage
device, such as data storage device 130 (FIG. 1)/140 (FIG. 1)/430 (FIG.
4).
Referring again to FIG. 1, in certain embodiments, library controller 160
is integral with host 390. In other embodiments, controller 160 is
external to host 390. In those external embodiments, library controller
160 (FIG. 1) communicates with host computer 390 (FIGS. 1, 3) via
communication link 392.
Referring now to FIG. 2B, library controller 160 includes microprocessor
262, volatile memory 264, and non-volatile memory 266. In certain
embodiments, microprocessor communicates with volatile memory 264 via
communication link 263. In other embodiments, volatile memory 264 is
integral to microprocessor 262. Microprocessor 262 communicates with
non-volatile memory 266 via communication link 265. Library operating
system 268 is stored in non-volatile memory 266. Operating system 268
comprises a computer program product which controls the operation of data
storage and retrieval systems 100 (FIG. 1)/400 (FIG. 4), and tape
subsystem 320 (FIG. 3).
Referring again to FIG. 1, operator input station 150 permits a user to
communicate with Applicant's automated data storage and retrieval system
100. Devices 180 and 190 each comprise information buffers. In certain
embodiments, devices 180 and/or 190 comprise a Direct Access Storage
Device ("DASD") cache. In certain embodiments DASD cache 180 and 190
comprise a plurality of hard disk drives which are configured into one or
more RAID arrays. In certain embodiments, information transferred between
host computer 390 and data storage and retrieval system 100 is buffered in
DASD caches 180 and 190 before being recorded on other data storage media,
such as one or more magnetic tapes. Import/export station 172 includes
access door 174 pivotably attached to the side of system 100. Portable
data storage cartridges can be placed in the system, or in the
alternative, removed from the system, via station 172/access door 174.
FIG. 4 shows system 400 which comprises another embodiment of Applicant's
data storage and retrieval system. System 400 includes first storage wall
402 and second storage wall 404. Storage walls 402 and 404 each include a
plurality of storage elements in which can be stored a plurality of
portable data storage cartridges. System 400 includes one or more data
storage devices, such as device 430. Device 430 comprises a floppy disk
drive, an optical disk drive, a magnetic tape drive, and the like. System
400 further includes operator control panel 450 (not shown in FIG. 3).
System 400 further includes library controller 460. Library controller 460
controls the operation of assessor 410 and data storage device 430.
Controller 460 is configured similarly to controller 160 shown in FIG. 2B.
System 400 further includes one or a plurality of portable data storage
cartridges, such as tape cartridges 370. Each cartridge contains a data
storage media internally disposed therein, such as data storage media 360
(FIG. 3).
Referring again to FIG. 3, tape subsystem 320, such as data storage and
retrieval system 100/200, receives commands from the HSM program 310 in
the host system 390 and performs the operations requested by the HSM
program 310, such as migration and recall, to transfer data between the
host system 390 and the components managed by the tape subsystem 320. In
preferred embodiments, the tape subsystem 320 can simultaneously process
numerous input/output requests from the host system 390 and any other
attached system directed toward the tape drives 330/340 and tape
cartridges 370 managed by the tape subsystem 320. Moreover, in certain
embodiments HSM program 310 in the host system 390 is capable of
multi-tasking, simultaneously executing numerous input/output operations,
and simultaneously transmitting multiple I/O requests to the tape
subsystem 320 to execute.
In further embodiments, a plurality of host systems 390 may communicate
with the tape subsystem 320 and/or a host system 390 may communicate and
transfer data to a plurality of tape subsystems 320, each subsystem
providing access to a library of tape cartridges.
FIG. 5 shows a block diagram depicting an industry-standard image of
information stored on a data storage medium, such as a portion of magnetic
tape 500. The information written on tape 500 includes file 520 and file
530. File 520 is the (N)th file stored on tape 500 and file 530 is the
(N+1)th file stored on tape 500. Files 1 through (N-1) are stored on
portion 510 of tape 500.
File 520 includes header label group 521, data 523, and trailer label group
525. Tape mark 522 is disposed between header label group 521 and data
523. Tape mark 524 is disposed between data 523 and trailer label group
525. Tape mark 526 is disposed after trailer label group 525. Thus, file
520 includes three (3) tape marks, i.e. tape marks 522, 524, and 526.
File 530 includes header label group 531, data 533, and trailer label group
535. Tape mark 532 is disposed between header label group 531 and data
533. Tape mark 534 is disposed between data 533 and trailer label group
535. Tape mark 536 is disposed after trailer label group 535. Thus, file
530 includes three (3) tape marks, i.e. tape marks 532, 534, and 536.
Tape mark 540 is disposed after tape mark 536. Tape mark 536 in combination
with tape mark 540 comprises double tape mark 550. Double tape mark 550
signifies that file 530 is the last file written on tape 500. Thus,
portion 560 of tape 500 contains no information.
FIGS. 6A-6E, 8, and 9, illustrate prior art methods to write information to
tape 600. Referring to FIG. 6A, tape 600 includes (N-1) files. The (N-1)th
file ends with trailer label group 620 followed by tape mark 630 and end
of file tape mark 640. Tape mark 630 in combination with tape mark 640
comprises double tape mark 650. As noted above, double tape mark 650
identifies the end of information stored on tape 600. Thus, no files are
stored on portion 660 of tape 600.
In step 810 (FIG. 8), an attached host computer, such as host computer 390
(FIG. 3), instructs a data storage device, such as data storage device 130
(FIG. 1), to write new information on a designated data storage medium,
such as tape 600. In step 820 a robotic accessor, such as accessor 110
(FIG. 1), retrieves and transports the portable data storage cartridge
housing tape 600. In step 830, that portable data storage cartridge is
inserted, i.e. mounted, in data storage device 130.
In step 840, data storage device 130 advances tape 600 in either the
forward or the reverse direction as needed until double tape mark 650 is
found. As those skilled in the art will appreciate, data storage device
130 includes read/write head 132 (not shown in FIGs.) internally disposed
therein. Upon locating double tape mark 650, the movement of tape 600 is
stopped. In step 850, a Back Space File command ("BSF") command is issued
to tape drive 130 and tape 600 is moved to position read/write head 132
between tape mark 630 and tape mark 640, i.e. to about position 601 which
is shown on FIG. 6B. Read/write head 132 is positioned at about point 601
on tape 600 at time T.sub.0.
FIG. 9 summarizes the prior art method to write file 680 to tape 600
starting at about point 601. Referring now to FIGS. 6C and 9, in step 910
header label group 681 is written to tape 600 starting at about position
601. After header label group 681 is written to tape 600, in step 920 tape
mark 682 is written to tape 600 adjacent header label group 681. After
writing tape mark 682 to tape 600, in step 930 data 683 is written to tape
600 adjacent tape mark 682. In step 940 tape mark 684 is written to tape
600 adjacent data 683. In step 950 trailer label group 685 is written to
tape 600 adjacent tape mark 684. In step 960 tape mark 686 is written to
tape 600 adjacent trailer label group 685.
After writing header label group 681, tape mark 682, data 683, tape mark
684, trailer label group 685 and tape mark 686, at time T.sub.1 read/write
head 132 is positioned at about point 602 of tape 600. Those skilled in
the art will appreciate that the time period between T.sub.0 and T.sub.1,
.DELTA.T.sub.Information Write, represents the time required to write file
680 to tape 600.
Referring now to FIG. 6D, in step 970 tape mark 687 is written to tape 600
adjacent tape mark 686 to form double tape mark 690. After writing tape
mark 687, read/write head 132 is disposed adjacent point 603 on tape 600.
In step 980 a Back Space File command is issued which causes tape 600 to
move in the reverse direction such that read/write head 132 is positioned
between tape marks 686 and 687. In step 990 tape 600 is moved such that
read/write head 132 is again disposed adjacent point 602 at time T.sub.2.
Those skilled in the art will appreciate that the time interval between
time T.sub.1 and time T.sub.2, i.e. .DELTA.T.sub.Head Reposition,
represents the time required to write tape mark 687 and to reposition tape
600 such that read/write head 132 is disposed adjacent point 602.
Referring now to FIG. 6E, graph 605 summarizes temporal and positional
information regarding the prior art process discussed above. The time
interval .DELTA.T.sub.Prior Art between the commencement of writing
information 680 to tape 600 and the commencement of writing a subsequent
file to tape 600, i.e. time interval 606, comprises both
.DELTA.T.sub.Information Write, i.e. time interval 607, and
.DELTA.T.sub.Head Reposition, i.e. time interval 608. Those skilled in the
art will appreciate that writing (N) files to tape 600 using prior art
methods necessarily requires Total Time.sub.Prior Art which equals:
##EQU1##
where .DELTA.Ti.sub.Prior Art is the time to write the (i)th file to the
tape. As discussed above, the time to write the (i)th file using prior art
methods includes .DELTA.T.sub.Information Write and .DELTA.T.sub.Head
Reposition. Therefore, Total Time.sub.Prior Art necessarily equals:
##EQU2##
Needless to say, as (N) increases, the aggregate time required to write (N)
double tape marks, issue (N) Back Space File commands, and to move the
tape backwards (N) times, also increases.
In marked contrast, however, when writing (N) files to a data storage
medium, such as a magnetic tape, Applicants' method eliminates the need to
reverse the movement of the tape (N) times and eliminates the need to
write a double tape mark (N) times. Thus, the total time to write (N)
files to a tape storage medium using Applicants' method is:
##EQU3##
FIGS. 7A-7F, 8, 10, and 11 summarize Applicants' method to write
information to tape 700. Referring now to FIG. 7A, tape 700 includes (N-1)
files written on portion 710. No information has been written to portion
760 of tape 700. The last file written to tape 700 ends with trailer label
group (N-1), tape mark (3N-1), and end of file tape mark 740.
Referring now to FIG. 7B, when tape 700 is mounted in a data storage
device, such as device 130 (FIG. 1), and device 130 receives a WRITE
command from an on-line host computer, such as host computer 390,
Applicants' method follows steps 810 (FIG. 8), 820 (FIG. 8), 830 (FIG. 8),
840 (FIG. 8), and 850 (FIG. 8) to position read/write head 132 at about
position 701. Thereafter beginning at time T.sub.0, file 770 is written to
tape 700 starting at position 701. File 770 includes header label group
(N), tape mark (3N), data (N), tape mark (3N+1), trailer label group (N),
and tape mark (3N+2). Referring now to FIG. 10, in steps 1010 through 1060
header label group (N), tape mark (3N), data (N), tape mark (3N+1),
trailer label group (N), and tape mark (3N+2) are successively written to
tape 700 to produce the image shown in FIG. 7C.
After writing file 770 to tape 700, read/write head 132 is positioned at
point 702 on tape 700 at time T.sub.1. Rather than issuing a set of
commands comprising a Write Tape Mark ("WTM") command followed by a Back
Space File ("BSF") command, i.e. writing an End Of File tape mark after
tape mark 776, moving tape 700 in the reverse direction, and positioning
read/write head 132 between tape mark 776 and the End Of File tape mark,
in step 1070 host 390 instead issues a DEFERRED CONDITIONAL WRITE TAPE
MARK command ("DCWTM" command). Upon receipt of such a DCWTM command, in
step 1080 data storage device 130 activates an internal indicator, i.e.
DEFERRED CONDITIONAL TAPE MARK INDICATOR ("DCTMI") 705, but causes no
immediate movement of tape 700.
A DCTMI, such as DCTMI 705, remains set for only a defined time interval,
i.e. the deferred conditional tape mark indicator time interval. In
certain embodiments, the deferred conditional tape mark indicator time
interval is encoded in software/firmware, and therefore, cannot be
modified by the user. In these embodiments, the deferred conditional tape
mark indicator time interval is specified by tape library manufacturer. In
certain embodiments of Applicants' invention a DCTMI remains set for about
ten seconds, i.e. the deferred conditional tape mark indicator time
interval has a specified duration of about ten seconds. In other
embodiments, the deferred conditional tape mark indicator time interval
has a specified duration less than about ten seconds. In still other
embodiments, the deferred conditional tape mark indicator time interval
has a specified duration greater than about ten seconds.
While DCTMI 705 remains set, tape drive 130 keeps read/write head 132
positioned adjacent point 702 on tape 700. As a general matter, the DCWTM
command is quickly followed by a WRITE command associated with the
recording of a new file. However, in the event data storage device 130
receives any command which causes motion or synchronization of tape 700,
such as a REWIND command, a READ command, or a DEMOUNT command, i.e. a
command that does not explicitly cause writing, erasure, or formatting of
media 700, then in step 1090 Applicants' method transitions to step 1110.
A command that implicitly causes writing, erasure, or formatting, of the
media only to force synchronization also causes Applicants' method to
transition to step 1110.
On the other hand, if data storage device 130 receives, for example, a
subsequent WRITE command, a WRITE TAPE MARK command, a MARK LOGICAL BLOCK
command, or a SCALE CAPACITY COMMAND, while DCTMI 705 remains set, then
Applicants' method transitions to step 1097 wherein the DCTMI is reset.
Thereafter, data storage device 130 executes the follow-on command. For
example, if the command received in step 1095 is a WRITE command to record
file 780 to tape 700, then in step 1097 Applicants' method resets DCTMI
705 and transitions to step 1010 to record file 780 to tape 700.
Referring now to FIGS. 7D and 10, upon receipt of a WRITE c
