This chapter discusses how to manage the same type of media recorded in different densities and how to separate cartridges written in the old density from cartridges written in the new density.
In this overview, you gain an understanding of:
Restrictions and the possible problems you may encounter
Examples of tape drives that record on the same media in different densities
Recommended solutions
Often, new tape drives are introduced that use existing tape media, but record at a higher density. These new drives can often read tapes recorded in the old density, but they cannot write in the old density. The older tape drives can neither read nor write in the higher density.
Because of these restrictions, you may encounter the following problems:
When a tape written in the new density is mounted on an older drive, the older drive cannot read the tape.
When storage management applications try to fill-up partially used tapes by appending additional files at a later time, it will fail if the tape was written using a different density than one to which a new tape drive can read but cannot write.
If you have a mix of both older and newer tape drives in your libraries, you must manage your tape cartridges that are of the same media type.
The following examples show tape drives that record on the same media, in different densities:
T10000 Media used by T10000A and T10000B Tape Drives
The T10000B tape drive uses the same media as the T10000A, but writes data at double the T10000A's density. The T10000B can read T10000A media and can reclaim (write from beginning of tape) it for writing T10000B density data, but it cannot append data to a previously written T10000A.
The T10000A drive can reclaim a T10000B cartridge for writing T10000A density data, but can neither read from, nor append data to a T10000B cartridge.
9840 Media used by T9840A, T9840B, T9840C and T9840D Tape Drives
Manage 9840 media when a combination of T9840A, T9840B, T9840C, and/or T9840D drives are present, because:
T9840A and T9840B
The T9840A and T9840B tape drives use the same media and record in the same density.
T9840C
The T9840C uses the same media as the T9840A and T9840B, but records at double the density.
T9840D
The T9840D writes at almost double the T9840C drives density.
Manage 9840 media when a combination of T9840A, T9840B, T9840C, and/or T9840D drives are present.
9940 Media used by T9940A and T9940B Tape Drives
T9940A
The T9940A drive can reclaim a T9940B cartridge for writing single density data, but can neither read from, nor append data to a T9940B cartridge.
T9940B
The T9940B tape drive uses the same media as the T9940A, but writes data at double the T9940A's density. The T9940B can read T9940A media and can reclaim it for writing double density data. However, it cannot append data to a previously written T9940A cartridge.
ACSLS has tools you can use to manage common media on which two or more types of drives can write, but are in incompatible recording densities. The client application must use these tools to manage the read/append data incompatibilities.
Manage drives that record on common media in different densities within an ACS by either:
Replacing all of the older drives in an ACS with the new drives at the same time.
This is the simplest and safest strategy. Using this strategy, you avoid the problems caused by managing a combination of drives using different densities. If you are unable accomplish this, you can gradually replace the older drives with the new drives, as discussed in the second bullet.
Note:
Do not append files to any tapes written in the old recording density after replacing the old drives with the new drives. With Veritas NetBackup, this is done by suspending the tapes.Gradually replacing the older drives with the new drives.
This requires you to manage the common media recorded in different densities. You can do this by:
Using the recording format information returned when the cartridge is dismounted in SL8500 and SL3000 libraries to manage media. This is discussed in the next section.
Creating separate ACSLS pools for each format.
Using the facilities of a backup application (for example, Veritas NetBackup, Legato NetWorker, IBM Tivoli, or CA BrightStor) to manage media pools.
When a cartridge is dismounted from a modern tape drive in a modern library, the recording format of the cartridge is reported to ACSLS. ACSLS saves the recording format in its database. You can use the display volume command to display this information.
Recording format is reported by:
Libraries:
SL3000
SL8500 (with 4.10 or later firmware)
Tape Drives:
All T10000 tape drives (with 1.38 or later firmware)
T9840A, T9840C, and T9840D (All T9840 tape drives except the T9840B.) (with 1.4.2 or later firmware)
T9940A and T9940B tape drives (1.4.2 and later firmware)
The example below describes how to manage T10000 media recorded in both T10000A and T10000B formats. Use the following table to apply the procedure to your specific case:
| Old Format Drive(s) | New Format Drive(s) |
|---|---|
| T10000A | T10000B |
| T9940A | T9940B |
| T9840A/T9840B | T9840C or T9840D |
| T9840C | T9840D |
Note:
The discussion below uses the following syntax conventions for commands and utilities:Commands and Utilities entered as is are in bold.
Variables (you must enter the exact value) are in italics.
After the T10000B drives are installed, use the recording format information to mount cartridges on compatible tape drives. Again, cartridges written at T10000A density can be read by either T10000A drives or T10000B drives, but only T10000A drives can append data written in a T10000A format. Only T10000B drives can read or append to cartridges written in a T10000B format.
No special processing is necessary when mounting scratch cartridges. When you write the cartridge from beginning-of-tape, the previous recording format does not matter.
To select a drive to read or append to a cartridge with data already recorded on it, follow this procedure. The following commands identify drives that can read and write a cartridges recording format.
Mounting Non-scratch Cartridges
Display the recording format of the cartridge.
display volume vol_id -f recording_format_family recording_format_model
The recording format for this volume is displayed.
Use the following query command to identify a compatible drive:
query mount vol_id
Drives compatible with a cartridge are displayed.
Select the correct drive type before mounting the cartridge.
This query command returns both T10000A and T10000B drives (because both drive types are compatible with T10000 media).
Use the drive type to separate T10000As from T10000Bs.
Selecting the first compatible drive in the list minimizes pass-thru and improves library performance.
Mount the cartridge on a drive compatible with the recording format with the following command:
mount vol_id drive_id
Migrating to the New Recording Format
When all the data on the cartridge has expired, you can re-write the cartridge from beginning-of-tape, in a new recording format.
For more information on expired cartridges, refer to "Populating the LSM".
After all T10000A drives are converted to, or replaced by T10000B drives, all T10000 media can be used by T10000B drives if data is not appended to cartridges written in T10000A format.
The example below describes how to manage 9940 media recorded in both T9940A and T9940B densities. The following procedure applies to all cases where different tape drives record on a common media, in different densities. Use the following table to apply the procedure to your specific case:
| Old Format Drive(s) | New Format Drive(s) |
|---|---|
| T10000A | T10000B |
| T9940A | T9940B |
| T9840A/T9840B | T9840C or T9840D |
| T9840C | T9840D |
| SDLT 220 | SDLT 320 |
Identify all 9940 data (non-scratch) cartridges in the ACS, and assign them to a T9940A pool. Do this before installing T9940B drives in an ACS that has T9940A drives.
Now you can assign 9940 scratch cartridges to either the T9940A or T9940B pool.
Define T9940A and T9940B media pools using the following command:
define pool pool_id
Report all 9940 media.
You can do this by using either the display volume command (option 1) or a custom volrpt (option 2), as shown below:
Results write a file.
Option 1
Use the display volume command to write the results to a file.
display volume * -media STK2P > filename
where:
All 9940 tape cartridges (media STK2P) are reported.
filename is the filename to which the output is written. The ACS ID in which the cartridge is located is also listed.
Read the output, selecting cartridges from specific ACS(s), if desired.
If you want cartridges from one ACS, use the -home operand to only select cartridges from this ACS.
display volume * -home acs_id.*,*,*,* -media STK2P> filename
Option 2
Use the custom volrpt for all volumes in the ACS. The results write a file:
volrpt -d -f custom_volrpt_file -a acs_id > filename
where:
custom_volrpt_file is the filename specifying the fields reported in a custom volrpt. The following fields are reported:
VOLUME_ID 6 2 MEDIA_TYPE 7 2 VOLUME_TYPE 4 2
acs_id is the ID of the ACS that you are managing.
filename is the filename to which the output is written.
Read the output, selecting only the volumes with a media type of STK2P.
Assign the selected volumes to the appropriate pools.
Assign all non-scratch (VOLUME_TYPE = D) cartridges to the T9940A pool using the following command:
set scratch off pool_id vol_id
Assign the scratch cartridges (VOLUME_TYPE = S) to either the T9940A or T9940B pools using the following command:
set scratch pool_id vol_id
After the T9940B drives are installed, use the pools to mount cartridges on compatible tape drives.
Again, cartridges written at T9940A recording density can be read by either T9940A drives or T9940B drives, but only T9940A drives can append data on 9940A media. Only T9940B drives can read or append to cartridges written at 9940B recording density.
The following commands can be used to identify, select and mount cartridges from the pool appropriate for a T9940A or T9940B drive. Use the pools to ensure you are mounting cartridges on the correct drive.
Note:
If you want to mount a scratch cartridge on the correct drive type, follow procedure A. If you want to mount a non-scratch cartridge with data already recorded on it, follow procedure B.Procedure A - Mounting Scratch Cartridges
Query drive(s) to identify drive types.
query drive drive_id | all
Identify the correct pool (media type) for the cartridges to be mounted on the desired drive.
Mount scratch cartridges to a drive from the specified pool.
mount * drive_id pool_id
Procedure B - Mounting Non-scratch Cartridges
Display the status of drives compatible with a cartridge.
display volume vol_id -f pool
The pool for this volume is displayed.
Identify a compatible drive using the query command.
query mount vol_id
Drives compatible with a cartridge are displayed.
Select the correct drive type before mounting the cartridge. This query command returns both T9940A and T9940B drives (because both drive types are compatible with 9940 media).
Use drive type to separate T9940As from T9940Bs.
Mount the cartridge on the selected drive.
mount vol_id drive_id
When all of the data on the cartridge has expired, you can migrate the scratch cartridges to the pool for the new recording density. Because T9940A and T9940B drives can re-initialize cartridges in their density, scratch cartridges can be reassigned to a different pool.
set scratch pool_id vol_id
After all T9940A drives are converted to, or are replaced by T9940B drives, all 9940 media can be used by T9940B drives, if data is not appended to cartridges written in T9940A recording density.