Moving Data from one TSM storage pool to another

[rstockton]

When data is moved (Move Data command) from one storage pool to another and a same file or files reside on the move to storage pool, will TSM not write the new file or will it write it as a copy?   

I believe and I have talked with others that also believe TSM is smart enough to not write a duplicate, but I need a definite answer of what will happen if possible.

Thanks,

Russell

[nifipro]

Hello,

When moving STGPOOL, all data in the primary stg are moved to the destination stgpool.
For example, if you have a disk stg and you want to move to another tape stg, the data(files) will be migrated to tape stg. The same thing for disk to disk..
Move command usually move entire file to the new destination.

Best R.

[rstockton]

Thanks for the information. 

So, if a file already resides on the move to storage pool, and a duplicate file resides on the move from storage pool TSM will write the file from the move as a duplicate?

[Justin Derrick]

I spent some time with Russell yesterday and we ran some experiments on their Dev server.

TSM *is* smart enough to *NOT* make additional copies when pushing data back *up* to a higher level.

The trick is to turn off the migration to the storagepool you are trying to move data from.

So if you have a Disk tier, which moves data down to a Tape tier, but you're trying to move that data back onto disk, you have to run:

Code Select Expand

update stgpool disktier nextstgpool=""

Then, you move the data from the tape volumes back up to the disk tier:

Code Select Expand

move data tape4852 stgpool=disktier

If you do some SQL queries on the internal 'contents' table, you can see that the disk tier now contains the data from tape4852, and it contains only one copy.

-JD.

[rstockton]

Justin, thanks for your help verifying this.  It was a good learning experience.