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Re: [Networker] Migrating data from staging disk to LTO3 tape
2005-09-28 16:46:53
Itzik,
I am presently migrating 8 file systems to 8 tape drives simultaneously
via one Sun V880. When I said I was getting 10-20 MB/sec of throughput
to the tape drives, I mean when they are all running at once.
So my question really is about problems people may have had with LTO3's
at slower data rates? And I am also wondering if anyone knows of a way
to feed 1 tape drive with more than 1 disk migration session?
Thanks for the reply.
Mark
Itzik Meirson wrote:
Having such a limited throughput to your LTO2 drives points to very slow
read capability of your disk system.
I would suggest that first of all you figure out why your disk (backup)
device is not capable of providing higher read throughputs.
You may have to check the service time for your device and the total
throughput read+write.
It might very well be that if you have multiple processes (save streams)
writing to the same device you are reading from with only one stream
(the staging process), the writes will monopolize on the device.
I would try to test the read throughput by staging at a time that no new
backups are directed to that disk device.
Itzik
-----Original Message-----
From: Legato NetWorker discussion
[mailto:NETWORKER AT LISTSERV.TEMPLE DOT EDU] On Behalf Of Mark Davis
Sent: Wednesday, September 28, 2005 19:00
To: NETWORKER AT LISTSERV.TEMPLE DOT EDU
Subject: [Networker] Migrating data from staging disk to LTO3 tape
We are looking at upgrading the drives in our tape library to
LTO3 technology. My concern is with cloning/migrating data
from our staging drives to tape. With our present
environment, the throughput rate to our existing LTO2 drives
ranges between 10 MB/sec to 20 MB/sec. With the
LTO3 drives rated at 60 MB/sec, I am worried we will get into
some serious "shoe shining" with the LTO3's, due to our
inability to reach the streaming rate. This shoe shining,
meaning forcing the tape to continually stop, reverse, and
move forward again during recording, would cause significant
wear and tear on the media and the drives.
On area where I could see improvement would be to send more
than one clone/migration session to a single tape device.
Does anyone know if this is possible?
Is anyone presently cloning/migrating staging disk to LTO3
drives, and have there been any issues?
Thanks very much.
Mark Davis
--
Mark Davis
Legato NetWorker Support - I.T.S
University of Western Ontario
email: davism AT uwo DOT ca
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