February 10, 2015
Multiple Parallel Tapes on 3000 Backups
Editor's note: When I saw a request this week for a copy of HP patch MPEMX85A (a patch to STORE that enables Store-To-Disk) for older MPE/iX releases, it brought a storage procedure request to mind.
I'm dealing with some MPE storage processes and need assistance. You would think after storing files on tapes after 10-plus years, we would have found a better way to do this. We use TurboStore with four tape drives and need to find a way to validate the backup. Vstore appears to only have the ability to use one tape drive. Currently I have some empty files scattered through the system and use a separate job to delete them, remount the tapes and restore, trying to access all four drives.
When using vestore:
vstore [vstorefile] [;filesetlist]
It seems that vstorefile is looking for a file equation similar to:
File t; dev=tape
vstore *t;@.@.@; show
This is why it appears that I can't use more than one tape drive, unless they are in serial, while we want to use four drives in parallel. What method or software should I be using?
Mark Ranft of Pro3K replies:
We always found that DLT 8000 tapes worked well in parallel. When the backup got so big that it wouldn't fit on two DLT 8000 tapes, we split the backup, putting the databases on two tapes in parallel and everything else on a third tape. Keep in mind, we didn't have a backup strategy. We had a recovery strategy and backups were a part of that. We found, for us, organizing backups in this manner allowed us to speed recovery — which was far more important than anything else.
You can achieve good times doing Store-to-Disk backups. But then what? Do you back up the STD to tape and send it offsite? FTP it somewhere? The recovery times on getting this back are too slow.Tracy Johnson adds
I think you can use VSTORE to read multiple tape drives in parallel or series using the ;RESTORESET parameter.
So you make four file equations.
Drop the beginning file single backreference to a equation (like we learned in olden times), and put the four new ones with the ;RESTORESET= parameter instead. It is one of those things that fooled me first time I saw it, and it took about 10 minutes getting used to seeing it.
The parenthesis around the file equations are placed differently:
;RESTORESET = (*tape1,*tape2,*tape3,*tape4)
But if the tapes were not also created in parallel, it may not help in the latter case.
Ray Legault adds
I use three DLT8000's and run a Vstore every week.
! setvar _drive "(*p1),(*p2),(*p3)"
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