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[Networker] Question on drive target sessions?
2006-11-24 00:32:44
This question concerns why NetWorker sometimes fails to start multiple
sessions on a device. I don't see this that often,
but here's an example:
I was running a group with 1 client. The client has 6 save sets. I start
the group (level full), and there's only one writable volume for
the given pool. The other is set Read-only. NetWorker loads the tape but
only sends one save set to the tape. The rest are pending. This seems odd
because the target sessions on the device was set to 5, the client
parallelism is 6 and the group parallelism was set to 0.
Anyway, it just sits there running that silly save set for the longest
time, and the rest are doing nothing. Meanwhile it keeps asking for another
writable tape. Obviously, it wants to kick of the rest, but why the heck
can't it just run some of them on the same device it's
writing the other save set to? There were no other groups running, so
there's plenty of room.
The tape library has 4 drives, and the server parallelism is set to 20
(5 per device). We're running 7.2.2 on Solaris server. The storage
node is running Linux (NW 7.2.2) and manages the library.
Now, I finally set the other tape (was read-only) to appendable. Within
30 seconds, NetWorker then stops requesting a writable tape
(issues event cleared message) and then starts to load the other tape.
However, before it loads it it then sends 4 of the remaining 5 save sets
to the device
that the first one was writing to. After mounting the other volume it
sends the 6th and last save set to that device.
I suppose it's conceivable that it was just coincidence and that it took
it that long to figure out what it wanted to back up? I didn't think
it generally mattered when running fulls even if a lot of files are
involved? Anyway, assuming not, why the heck did it have to wait until
it had another appendable tape to send more save sets to the first one
if the first device was only running 1 session?
Does anyone else see this behavior ever? I ran 20 other groups today,
all with various number of clients, and I never saw this, so it doesn't
occur most of the time.
Thanks.
George
--
George Sinclair - NOAA/NESDIS/National Oceanographic Data Center
SSMC3 4th Floor Rm 4145 | Voice: (301) 713-3284 x210
1315 East West Highway | Fax: (301) 713-3301
Silver Spring, MD 20910-3282 | Web Site: http://www.nodc.noaa.gov/
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