ADSM-L

Re: DIRMC - Are copypool reclamation performance issues resolved or not.

2005-03-19 17:09:50
Subject: Re: DIRMC - Are copypool reclamation performance issues resolved or not.
From: "Rushforth, Tim" <TRushforth AT WINNIPEG DOT CA>
To: ADSM-L AT VM.MARIST DOT EDU
Date: Sat, 19 Mar 2005 16:09:34 -0600
Restore Order processing did definitely fix one problem. DIRMC still
solves other problems if you are storing data on tape.

We used to tell our users that backups were stored on disk from the
previous night's backups so if they did restores during the day then
there would be no tape mounts.

We have 1 group that uses TSM to clone DB's from prod onto a test box.
All DB files would be backed up the previous night, but when the user
went to do the restore tape mounts were occurring (and to make matters
worse we were experiencing the corrupt CM issue on LTO tapes at the
time!).

I thought the reason tapes were being mounted was perhaps because they
were selecting a directory plus all of the files to be restored (and the
directory of course was backed up days, months, or years ago) so was on
tape.  But this wasn't the case, I don't remember the exact restore
syntax now but this made us implement DIRMC and we've been happy since!
(Perhaps this was some other bug here?)

 So DIRMC is being used successfully for us so that no unnecessary tape
mounts occur to restore a directory entry here and there.  (We have
limited tape drives, usually doing reclaims during the day - sometimes
with huge exchange db files which take a while to preempt).

So ensure you understand all of the issues before you decide to dump
DIRMC.

Tim Rushforth
City of Winnipeg 


-----Original Message-----
From: Kenneth & Susan Bury [mailto:kbury AT CAROLINA.RR DOT COM] 
Sent: Saturday, March 19, 2005 3:17 PM
To: ADSM-L AT VM.MARIST DOT EDU
Subject: Re: DIRMC - Are copypool reclamation performance issues
resolved or not.

Paul,

It is definitely, absolutely, positively, seen it myself - fixed....
Been
fixed for years. Forget DIRMC.

Ken

> -----Original Message-----
> From: ADSM: Dist Stor Manager [mailto:ADSM-L AT VM.MARIST DOT EDU]
> On Behalf Of Paul Fielding
> Sent: Saturday, March 19, 2005 16:06
> To: ADSM-L AT VM.MARIST DOT EDU
> Subject: Re: DIRMC - Are copypool reclamation performance
> issues resolved or not.
>
>
> Hi Richard,
>
> I took a look through the Quickfacts (something I should have
> done long ago).  It does indeed suggest that surrogate
> directories are created and the real directories are restored
> as they are hit.
>
> Has anyone really observed this to be genuinely true?  I have
> in the past observed the double-tape-mount theory, and though
> I understand it is supposedly fixed, I haven't heard anyone
> say "I have seen it, I know it works, you no longer need to
> keep a dirmc diskpool".
>
> Of course, if it is indeed working as designed now, it
> doesn't resolve the other dirmc issues currently being
> discussed in this thread.
>
> Is there anyone on the list who has in recent history decided
> to ditch using a dirmc diskpool altogether and done so with
> success on the restore side?
>
> regards,
>
> Paul
>
> ----- Original Message -----
> From: "Richard Sims" <rbs AT BU DOT EDU>
> To: <ADSM-L AT VM.MARIST DOT EDU>
> Sent: Saturday, March 19, 2005 4:44 AM
> Subject: Re: [ADSM-L] DIRMC - Are copypool reclamation
> performance issues resolved or not.
>
>
> > Paul -
> >
> > This generally falls under the TSM term Restore Order processing.
> > We've discussed it on the List before. I have an entry on
> it in ADSM
> > QuickFacts which you can refer to as a preliminary to
> further pursuit
> > in IBM doc.
> >
> >   Richard Sims    http://people.bu.edu/rbs
> >
> > On Mar 19, 2005, at 3:06 AM, Paul Fielding wrote:
> >
> >> I'd be interested in more discussion on this point.   My original
> >> understanding was actually a bit different that that.  The
> impression
> >> I had was that originally directory tree structures were restored
> >> before any files
> >> happened, period. Following that, files would be restored.
>  Net result
> >> -
> >> tapes might get mounted twice.
> >>
> >> Is my understanding incorrect? (could well be).  If this
> behavior has
> >> indeed been fixed so that directories are restored as they
> are hit on
> >> the tape (with a pre-created non-ACLed directory being
> created first)
> >> then it would
> >> indeed make sense that a DIRMC pool is no longer needed.
> >>
> >> Is there any documentation on this somewhere I can reference?
> >
>