Reg. Emergency log backup during restore.....

#1 (**permalink**) 04-19-2008, 08:03 PM

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Hi,

Recently, we had multi-disk failure on a Sun storedge T3 RAID-5
array and hence we lost all the data. We rebuilt the whole array after
replacing the faulty disks. We restored the whole database from our backups.

Remember, we had onbar parallel backups running on this system. Hence ,we
have to restore the logical logs to make the chunks online after the
restore. Otherwise as you know, chunks will be in inconsistency modes.
Sometime during the logical restore, onbar kicked of a log backup before the
log restore (I assume that is the emergency log backup left at the disk
failure stage).It backed up the logical log and started performing all the
log restores plus the one backed up just now. The chunks are online now.

My question

1) How did it get log data for backup (emergency log data) when the whole
RAID array is reinitialised due to multidisk failure ?
-- I mean where was the data for ONBAR to backup when everything was
destroyed ?

2) Could it be due to the logdbs was mirrored and might have been safe
somewhere else during that point ?
-- Even then we reinitialised the whole RAID array after replacing the
disks.

Please spare your views/comments.

Regards
Rajesh Rajasekaran
Informix Database Administrator
Forest Pharmaceuticals Inc.
(314) 493-7073

__________________________________________________ __________________
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Hi,


        Recently, we had multi-disk failure on a Sun =
storedge T3 RAID-5 array and hence we lost all the data. We rebuilt the =
whole array after replacing the faulty disks. We restored the whole =
database from our backups.

  Remember, we had =
onbar parallel backups running on this system. Hence ,we have to =
restore the logical logs to make the chunks online after the restore. =
Otherwise as you know, chunks will be in inconsistency modes.  =
Sometime during the logical restore, onbar kicked of a log backup =
before the log restore (I assume that is the emergency log backup left =
at the disk failure stage).It backed up the logical log and started =
performing all the log restores plus the one backed up just now. The =
chunks are online now.

My question


1) How did it get log data =
for backup (emergency log data)  when the whole RAID array is =
reinitialised due to multidisk failure ?

   -- I mean where =
was the data for ONBAR to backup when everything was destroyed ?


2) Could it be due to the =
logdbs was mirrored and might have been safe somewhere else during that =
point ?
     -- Even =
then we reinitialised the whole RAID array after replacing the =
disks.


Please spare your =
views/comments.

 

Regards
 Rajesh =
Rajasekaran
 Informix Database =
Administrator
 Forest Pharmaceuticals =
Inc.
 (314) =
493-7073

 
 
 
 

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the employee or agent responsible for delivering this e-mail to the =
intended recipient, you are hereby notified that any dissemination, =
distribution, copying or action taken in relation to the contents of =
and attachments to this e-mail is strictly prohibited and may be =
unlawful. If you have received this e-mail in error, please notify the =
sender immediately and permanently delete the original and any copy of =
this e-mail and any printout.

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#2 (**permalink**) 04-19-2008, 08:04 PM

On Tue, 27 Jan 2004 16:02:32 -0500, Rajasekaran, Rajesh wrote:

Oooo, RAID5 and MIME! You don't pay attention much do you?

NO RAID5! NO RAID5! NO RAID5! NO RAID5! NO RAID5! NO RAID5! NO RAID5!

And PLEASE no MIME!

> Hi,
>
> Recently, we had multi-disk failure on a Sun storedge T3 RAID-5
> array and hence we lost all the data. We rebuilt the whole array after
> replacing the faulty disks. We restored the whole database from our backups.

RAID5 should NEVER be used for databases, and IYAMO not at all for anything
that you care about. If you've never seen my postings on the subject and
cannot find them in the archive, email me and I'll enlighten you (assuming you
have not learned your lesson from this experience). But let's get beyond the
scolding to your question.

> Remember, we had onbar parallel backups running on this system. Hence ,we
> have to restore the logical logs to make the chunks online after the
> restore. Otherwise as you know, chunks will be in inconsistency modes.
> Sometime during the logical restore, onbar kicked of a log backup before the
> log restore (I assume that is the emergency log backup left at the disk
> failure stage).It backed up the logical log and started performing all the
> log restores plus the one backed up just now. The chunks are online now.
>
> My question
>
> 1) How did it get log data for backup (emergency log data) when the whole
> RAID array is reinitialised due to multidisk failure ?
> -- I mean where was the data for ONBAR to backup when everything was
> destroyed ?

The dbspace(s) containing the logical logs still on disk at the time of the
level 0/1/2 archive were saved along with the rest of the dbspaces and were
restored from that tapeset before the individual logical log restore begain.
If the last logical log was almost full at the time of the archive, then the
dbspace restore records and the logical log restore records which are written
to the active logical log probably were enough to fill that log causing a
switch to the next logical log and triggering the logical log backup.

> 2) Could it be due to the logdbs was mirrored and might have been safe
> somewhere else during that point ?
> -- Even then we reinitialised the whole RAID array after replacing the
> disks.

Nope.

Have fun, good luck, and remember to chant our mantra three times a day:

NO RAID5! NO RAID5! NO RAID5! NO RAID5! NO RAID5! NO RAID5! NO RAID5!

Art S. Kagel

> Please spare your views/comments.
>
>
> Regards
> Rajesh Rajasekaran
> Informix Database Administrator
> Forest Pharmaceuticals Inc.
> (314) 493-7073
>
>
>
>
>
> __________________________________________________ __________________ This
> e-mail and its attachments may contain Forest Laboratories, Inc. proprietary
> information that is privileged, confidential or subject to copyright
> belonging to Forest Laboratories, Inc. This e-mail is intended solely for
> the use of the individual or entity to which it is addressed. If you are not
> the intended recipient of this e-mail, or the employee or agent responsible
> for delivering this e-mail to the intended recipient, you are hereby
> notified that any dissemination, distribution, copying or action taken in
> relation to the contents of and attachments to this e-mail is strictly
> prohibited and may be unlawful. If you have received this e-mail in error,
> please notify the sender immediately and permanently delete the original and
> any copy of this e-mail and any printout.
>
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>
> Hi, 
>
>         New Roman">Recently, we had multi-disk failure on a Sun = storedge T3 RAID-5
> array and hence we lost all the data. We rebuilt the = whole array after
> replacing the faulty disks. We restored the whole = database from our
> backups.
>
>   Remember, we had = onbar
> parallel backups running on this system. Hence ,we have to = restore the
> logical logs to make the chunks online after the restore. = Otherwise as you
> know, chunks will be in inconsistency modes.  = Sometime during the
> logical restore, onbar kicked of a log backup = before the log restore (I
> assume that is the emergency log backup left = at the disk failure stage).It
> backed up the logical log and started = performing all the log restores plus
> the one backed up just now. The = chunks are online now.
>
> My question 
>
> 1) How did it get log data = for
> backup (emergency log data)  when the whole RAID array is =
> reinitialised due to multidisk failure ?
>
>    -- I mean where =
> was the data for ONBAR to backup when everything was destroyed ? 
>
> 2) Could it be due to the =
> logdbs was mirrored and might have been safe somewhere else during that =
> point ?
>     -- Even =
> then we reinitialised the whole RAID array after replacing the =
> disks.
> 
>
> Please spare your =
> views/comments.
> 
> 
>
> Regards
> Rajesh =
> Rajasekaran
> Informix Database =
> Administrator
> Forest Pharmaceuticals =
> Inc.
> (314) = 493-7073
> 
> 
> 
> 
> 
>
> _______________________________________________ _____________________&=
> nbsp;=20
> This e-mail and its attachments may contain Forest Laboratories, = Inc.
> proprietary information that is privileged, confidential or = subject to
> copyright belonging to Forest Laboratories, Inc. This e-mail = is intended
> solely for the use of the individual or entity to which it = is addressed.
> If you are not the intended recipient of this e-mail, or = the employee or
> agent responsible for delivering this e-mail to the = intended recipient,
> you are hereby notified that any dissemination, = distribution, copying or
> action taken in relation to the contents of = and attachments to this e-mail
> is strictly prohibited and may be = unlawful. If you have received this
> e-mail in error, please notify the = sender immediately and permanently
> delete the original and any copy of = this e-mail and any printout.
>
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#3 (**permalink**) 04-19-2008, 08:04 PM

On Wed, 28 Jan 2004 09:21:04 -0500, Art S. Kagel wrote:

> On Tue, 27 Jan 2004 16:02:32 -0500, Rajasekaran, Rajesh wrote:
>
> Oooo, RAID5 and MIME! You don't pay attention much do you?
>
> NO RAID5! NO RAID5! NO RAID5! NO RAID5! NO RAID5! NO RAID5! NO RAID5!
>
> And PLEASE no MIME!
>
So then after scolding Rajesh I go and forget to snip the MIME trailers. My
apologies to the list for wasting bandwidth.

Art S. Kagel

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