Hi,
I'm trying to determine a general ball park figure for what we should be
seeing for recovery speeds on our SDLT 220 drives which brings up some
questions. Here are the facts:
Quantum SDLT 220 gen 1 drives with gen 1 media
Averaging around 12 MB/sec write speeds
Target sessions = 5 per device
Linux Red Hat Dell storage node server
In recovering a recent saveset (multiple tapes), I noticed it seemed to
be averaging about 1 GB per minute, sometimes 2 GB per minute, so that's
anywhere from say 7 MB/sec to 17 MB/sec. Not bad in my opinion, but not
sure. I was recovering at most 1 of the streams that might have been
multi-plexed to the given tapes. I say 'might' because typically there's
always at least several streams writing to a given tape at a time. The
target sessions are set to 5 for all devices, but sometimes it will send
more, sometimes less depending. Obviously, depending on how much it has
to de-multiplex, speeds will vary. I have some questions:
1. All network speed aside, does the number of files and sizes of the
files in the saveset affect the speed of recovery for the saveset or
just the amount of the data and the speed of the drives?
2. In general, is it safe to say that recovery will be slower than
writing since it has to de-multiplex the data from the other streams
that were written at the same time?
3. What might you expect for recovery times knowing the speed of your
writes and target sessions? Can any rough estimates be expected?
4. Is there a way, aside from just eyeballing and watching the clock, to
calculate the speed that the data is being recovered at?
I see write speeds during backups but not recoveries.
Thanks.
George
BTW It would be nice, during big recovers, if NetWorker had the
capability to load up all available drives with the same number of
required tapes and perform multiple recovers at the same time from the
savesets on the tapes and somehow merge them on disk before continuing?
Would save a lot of time.
--
Note: To sign off this list, send a "signoff networker" command via email
to listserv AT listserv.temple DOT edu or visit the list's Web site at
http://listserv.temple.edu/archives/networker.html where you can
also view and post messages to the list. Questions regarding this list
should be sent to stan AT temple DOT edu
=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=
|
