I use Legato 7.0, but all my testing was on 6.1 on Tru64 5.1A on a Alpha
4100.
If your recovery takes longer than your backup it is one of two things.
1. You are not recovering all save sets in parallel off of the tape, and it
is running the tape through more than one time.
2. You disk devices are much slower at writing than they are at reading
(typical)
for 1. above, make SURE you select all data off of one tape so it doesn't
have to read the tape, rewind and then run through it a second time.
for 2. above, do a basic single LARGE file test backup(say 1GB or so). Back
it up to tape as a single file, restore it from tape as a single file.
Compare the speed of backup against speed of restore. They should be the
same. If not, investigate the write configuration of your disk drives. IE,
a RAID 5 is much slower writing than reading. If this is the problem, you
can't fix it without buying (expensive) hardware. You can verify the speed
issue by running this same test against a single hard drive, and comparing
the two.
-----Original Message-----
From: Jody Gregersen [mailto:Jody.Gregersen AT VISHAY DOT COM]
Sent: Tuesday, 17 June, 2003 01:58 PM
To: NETWORKER AT LISTMAIL.TEMPLE DOT EDU
Subject: [Networker] How do I minimize recovery time?
Hi,
I'm running Legato 6.1 using Tru64 5.1a on an ES40 attached to an ESL9326
jukebox with 8 TL891 drives. We are setting up for a DR test and I would
like to have the shortest recovery time possible. We run separate backups
rather than cloning. We can get about 500 GB backed up in about 5.5 hours
using a parallelism of 32 and 8 target sessions per drive (8 streams running
to 4 tapes simultaneously). To restore this setup takes about 24 hours. If
I run with a parallelism of 16, the backup takes about 8.5 hours. We
haven't tried a restore from those tapes. Does anyone know of an "optimum"
parallelism for restoring or some equation that could be used to determine
what a restore time might be?
Thanks,
Jody
Jody Gregersen
Infrastructure Engineer
Vishay Intertechnologies, Inc.
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