The idea of massive volumes is intriguing, but my concern would be
backup/restore. On some our non-z platforms we have huge volumes many times
the size of 3390-3. When one of them went south a while back, it took hours
and hours to get it restored. With RAID arrays, of course, that's not
supposed to happen; I think it was a problem with an SVC.
On the mainframe we take frequent full volume backups. The likelihood of
true failover (DR) is minuscule, and we use XRC mirroring for that
contingency anyway. On the other hand the probability of having to retrieve
an accidentally deleted or modified file is huge--it happens all the time
even for sysprog finger checks.
1. How long does it take to make a tape backup of a 32760 cylinder volume?
2. Where does that backup live?
3. How long does it take to restore a critical 10 track file from two weeks
ago that happens to live on the corner of cylinder 31753?
.
.
JO.Skip Robinson
Southern California Edison Company
Electric Dragon Team Paddler
SHARE MVS Program Co-Manager
626-302-7535 Office
323-715-0595 Mobile
[EMAIL PROTECTED]
"Van Dalsen,
Herbie"
<Herbie.VanDalsen To
@ELAVON.COM> [email protected]
Sent by: IBM cc
Mainframe
Discussion List Subject
<[EMAIL PROTECTED] Re: VTOC size
.EDU>
02/08/2008 05:46
AM
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IBM Mainframe
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<[EMAIL PROTECTED]
.EDU>
Mark,
I suppose that you have already got the answers that you wanted, This is
just an alternate idea.
When we initialized our Shark array's in 2004, we create a few with 1113
cylinders, a few 10017 and most 3339 cylinders.
The last two we installed, we had mainly 32760 Cylinder volumes, about
10 10017's and 2 3339's , 1 1113 and a 848 which we use to contain only
the master catalog, and nothing else.
The logic is this... In SMS allocation of small datasets goes to the
M1's medium to the M3/M9's and The massive VSAMS / IAM's to M27's
We have never had a major problem where our VTOCs were full before the
volumes, and this is the sizes...
M1 = INDEX(0,1,1) VTOC(0,2,15)
M3 = INDEX(0,1,7) VTOC(0,8,75)
M9 = INDEX(0,1,7) VTOC(0,9,75)
M27 = INDEX(0,1,4) VTOC(0,5,75)
Regards
Herbie
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