The RelabelScratch parameter is aimed for use with Virtual Tape Libraries (VTL) and instructs TSM to relabel the tape when it becomes a scratch tape

NOTE: Do you not use the parameter below TSM 5.5.3 as there is a major bug with this option which can cause your tapes to be relabeled incorrectly

Why is this parameter needed?  ( This is based on my experience with the Falconstor VTL Product)

When using VTL’s with De-Duplication, the Virtual Tape Library Engine and DeDupe Engine are separate subsystems ( either within the same System or in different Systems ). In these cases the VTL Engine is just a transient area for your data before it is deduplicated and is moved to the storage managed by the DeDupe Engine.

Over time TSM will expire old data, reclaim tapes and tapes will move back to the scratch pool. The problem is that the VTL and DeDupe engine do not know that these tapes have become scratch tapes and so will not remove the expired data. The only way that the VTL and DeDupe systems know that a virtual tape has become a scratch tape is when TSM starts writing on that virtual tape from the beginning again.

To overcome this problem the RELABELSCRATCH parameter was introduced. This will tell TSM that it should rewrite the internal TSM label on the virtual tape when it becomes a scratch tape. This will let the VTL and DeDupe engine know that the data on that tape can be removed from the VTL and DeDupe Engines.

To see how this parameter is set on your library

Run the following QUERY LIBRARY FORMAT=DETAILED and you get output like the following. Checkout the Relabel Scratch Option

tsm: SPIRITTSM55_SERVER1>query library format=detailed

Library Name: LB0.0.0.2
Library Type: SCSI
ACS Id:
Private Category:
Scratch Category:
WORM Scratch Category:
External Manager:
RSM Media Type:
Shared: No
LanFree:
ObeyMountRetention:
Primary Library Manager:
WWN:
Serial Number: 9EZ7Z00M08
AutoLabel: No
Reset Drives: No

Relabel Scratch: Yes

Last Update by (administrator): ADMIN

Last Update Date/Time: 02/04/2010 04:58:33

When using TSM Studio go to the Libraries Dataview in the Libraries and Volumes Category and check out the Relabelscratch column

To change the relabelscratch parameter the Library cannot have any activity to it

UPDATE LIBRARY libraryname RELABELSCRATCH=YES

where libraryname is the name of your Library

To change using TSM Studio

Right Click on the Library to bring up the Commands Menu and choose Edit

Check the Relabel Scratch Option and Press Ok

Posted in: TSM Studio