I am trying to verify that it is ok to use dual virtual tapes when backing up the entire system.. I realize all I have to do is duptap for the 2nd one at the end of the first one.. But... Is this a valid complete system backup that is usable for a restore system command on an alternate ipl device that uses the physical tape created from the duptap command due to the multiple labels caused by copying the second virtual tape at the end of the first...
I am hoping that using this procedure will cut my full system save time at least a little...
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5 replies Latest Post - 2012-07-18T10:29:26Z by willey
Pinned topic system backup using dual virtual tapes
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Updated on 2012-07-18T10:29:26Z at 2012-07-18T10:29:26Z by willey
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Re: system backup using dual virtual tapes2011-05-23T18:33:25Z in response to GA4T_ed_eversI hope I am understanding your questions/thoughts correctly and will try to answer:
Q1) Is it okay to use "dual virtual tapes"?
A1) Yes. It depends on how you are performing your save, but you can actually use up to 35 virtual tape devices at one time.
Q2) Is this a valid complete system backup that is usable for a restore system command on an alternate ipl device that uses the physical tape created from the duptap command due to the multiple labels caused by copying the second virtual tape at the end of the first?
A2) Yes, as long as the Licensed Internal Code is sequence 1 and OS is afterwards in the correct order, which it will be correct on the first volume. See KB19124111 (Entitled, must sign in) for the labels sequences. When you DUPTAP to append the second volume, you can specify TOSEQNBR(*END).
Q3) "I am hoping that using this procedure will cut my full system save time at least a little"
A3) There are many things that determine performance and depends on how and what you are currently writing to. To give you better performance on your backup to virtual tape, here are a few options:
- If you have BRMS, you could perform a parallel backup (performance seems to top off at about five virtual tape devices).
- If you don't have BRMS, you could use a CL to run the save commands in a concurrent format (From above, your backup appears to be sequential). This means running more than one save at a time. You could do this by performing your SAVSYS to a single drive and then afterwards, start QBATCH subssystem and break up your SAVLIB *NONSYS, SAVDLO, and SAV commands in multiple jobs using generics (ex. SAVLIB A*). Again, performance seems to top off at about five virtual tape devices/concurrent save jobs.
- Ensure that this partition/pool has the most memory and CPU as possible
- If you can, keep your image catalog in a separate ASP from the majority of your data so that you are not reading/writing from same set of disks.
- More info can be found in the virtual tape guide SG24-7164-00
- Brian B.
Re: system backup using dual virtual tapes2011-05-23T20:07:35Z in response to GA4T_ed_eversThank you for the quick detailed response... I will go and check the references you listed, to better understand the situation...
One thing that you did not specifically answer...
Go SAVE option 20, (setup for option 21), allows multiple save devices... That is why I was wondering if you specify multiple devices on that screen, will the system automatically save the complete system in the proper order..i.e. all system info necessary to be processed first on the first (virtual) device, then spread the rest to the other (virtual) devices specified... I was told at one time (recently) that it would work correctly, and I was scared to try it without further confirmation...
Specifically... I want to put multiple virtual devices on my option 21 and then duptap the results onto one tape in order of the virtual devices... Then be able to rely on the physical tape as a valid full system save with the ability to use it as sys restore on alternate ipl device...
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Re: system backup using dual virtual tapes2011-05-23T20:31:10Z in response to GA4T_ed_eversThe multiple devices on the GO SAVE 20/21 is made for sequential backups. Adding additional virtual or physical drives won't change the backup from sequential to concurrent or parallel. You will need a CL or BRMS for that. So to answer your question, since it is sequentially backing up, multiple drives will be in the correct order. If you use a CL for concurrent, then specify TOSEQNBR(*END) on the DUPTAP. If using BRMS, it will automatically figure it out for you through the media definition.
If you only want to perform a sequential backup through GO SAVE option 21, then you can create your image for up to 1TB.
- Another performance tip is to specify *IMGSIZ when creating your volume so that it doesn't take the huge performance hit of dynamically allocating storage. Instead, it allocates the storage up front.