Re: [Networker] Slow Cloning Speed
2005-09-15 15:47:21
Hey Adam,
In my experience, it isn't unusual to see slow cloning when you try to
clone one save set from a multiplexed volume. The tape drive is having
to go through the tape and only pick up the little chunks that are in
the desired saveset. So for example if you have a volume that had 8
save streams to it, and the native drive speed is 30BM/s the average
read speed(all things being equal) you could expect would be below
3.75MB/s. Probably lower due to the overhead of finding the little
chunks of data.
Best bet IMHO is to keep only savesets that your going to clone on one
set of volumes, and the savesets that your not going to clone on another
set of volumes. Then clone all of the savesets at the same time.
Later,
Joel
-----Original Message-----
From: Legato NetWorker discussion [mailto:NETWORKER AT LISTSERV.TEMPLE DOT EDU]
On Behalf Of Thomas, Adam (NIH/NIMH)
Sent: Thursday, September 15, 2005 2:21 PM
To: NETWORKER AT LISTSERV.TEMPLE DOT EDU
Subject: [Networker] Slow Cloning Speed
I'm running Networker 7.2 on a Linux workstation (RHEL 3, kernel 2.4.29)
with a Qualstar 5433 tape library containing two S-AIT drives.
When I try to clone a saveset on a tape with multiple multiplexed files
the job proceeds at less 1 MB/sec. At this rate it would take about a
week to clone one tape.
If I try to clone one of my archive tapes, where the savesets are not
multiplexed on the tape, the job proceeds at closer to 40MB/sec.
Note that for backups parallelism on the tape devices is set to four, so
the degree of multiplexing is fairly low.
Any ideas on how to speed things up?
-a
---
Adam Thomas adamt AT nih DOT gov
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