On Fri, Jul 21, 2006 at 08:36:14AM +1000, Tim Nicholson wrote:
> I have not had this particular one happen, but something similar.
>
> It seems that
> if you have another device available for the pool, even if
> that device is offline,
> and you have used up the target sessions for all other devices
> currently in use for that pool
> then NetWorker queues save sets for a volume, which it expects
> would be mounted on a new device.
>
> This would mean explain your situation (and some others).
I know I've seen a similar situation with a backup group that occurs
over the noon hour. (It's probably a combination of the fact it runs
when I'm at the office, and because of the smaller number of clients
that I've witnessed it.) Our device target sessions are set to 16,
server parallelism at 32, and group parallelism is 0. 16 streams should
handle all or most of the traffic, but it sends <16 to a drive (say 7,)
and queues up another tape drive. (Given the drives and media are
available, I understand this behavior.)
What I don't get is that new sessions "block" while Networker is loading
the second tape. The original writing tape doesn't get new sessions.
After the second tape loads, it gets a few sessions and the original
tape gets a bunch more. Sometimes there are cases where a second
available jukebox drive is not available. In that case, it still blocks
for a while, and then somehow internally times out and writes to the
original tape. I imagine that's what happens overnight too, but those
backups have many more savesets, don't have such a tight time window,
and I'm asleep so I really don't care. :)
It's possible it's also my environment - I have two jukebox drives and
one external/manual drive. Of course, Networker doesn't know or care
that it's manual -- it sees an available drive, and knows about
mountable, writable pool media, so perhaps it's waiting on me to load
it. I should disable the external over the noon run today and see if
that makes saveset-to-tape queuing more efficient.
I just know having two tapes in the jukebox for this group makes it run
a lot faster than just having one. This is about as far as I've gotten
troubleshooting this.
Dave
To sign off this list, send email to listserv AT listserv.temple DOT edu and
type "signoff networker" in the
body of the email. Please write to networker-request AT listserv.temple DOT edu
if you have any problems
wit this list. You can access the archives at
http://listserv.temple.edu/archives/networker.html or
via RSS at http://listserv.temple.edu/cgi-bin/wa?RSS&L=NETWORKER
|
