Restore Differential TDP SQL (parallel sessions)

[deivison]

Hello guys.


We have a TDP SQL backup that uttiliza 3 stripes and to restore the full backup TSM opens three parallel sessions during the restore increasing performance.

The problem is that when I try to restore a differential backup (Diff + Full) using three stripes where three sessions ask the same tape.
The tape is mounted on one of the sessions the other two are mediaw and the restore is not completed.

The stripes numbers are set in my Server.cfg and I am using SQL TDP 6.3.1

Can you help me to discover how you can restore a database using three sessions in parallel without them ask the same tape?

 

[moon-buddy]

At what part of the restore session does it starts asking for the same tape? Did it start with three sessions and then down to one?

 

[deivison]

Sessions already start asking the same tape and how two sessions are in mediaw the restore does not progress.

 

[moon-buddy]

Sessions already start asking the same tape and how two sessions are in mediaw the restore does not progress.

What happens when you just do a FULL restore? Three tapes are mounted?

 

[deivison]

What happens when you just do a FULL restore? Three tapes are mounted?

In Full restore the three sessions work in parallel correctly, being a different tape for each session and the restore is successfully completed. The problem is to restore the Diff + Full.

 

[moon-buddy]

Ok, it seems that DIFF backups just go on one tape.

I believe, this is what happens: TSM reads off the DIFF backup first and then the FULL.

See if this follows observed behavior.

 

[deivison]

Ok, it seems that DIFF backups just go on one tape.

I believe, this is what happens: TSM reads off the DIFF backup first and then the FULL.

See if this follows observed behavior.

I also believe that's it. One solution we found to solve this problem is to release the full restore first and then release the differential restore. Thus optimizing the restore time.

I will continue studying to find some solution and if I find I will share with you. If anyone has more ideas, please share.


Thanks for the help, moon-buddy!

 

[Trident]

hi,

You can force tsm to use one tapedrive. it will take more time.

just add /stripes=1 to your tdpsqlc restore command.