[OpenAFS] broken callbacks
Wed, 20 Apr 2016 17:54:20 +0200
To hunt down some performance problems on our AFS servers I started to
integrate some metrics to our Ganglia monitoring system via a dirty
hack; see for example
In that context 3 questions regarding nFEs and nCBs entered my mind:
- What's the meaning of those?
- I found some information about nFEs and nCBs in
"If nFEs or nCBs ever exceeds nblks, that is when the fileserver runs
out of callbacks." I found that those metrices have a similar
behaviour, but are usually not the same.
Should I consider to store just "max(nFEs, nCBs)" or can I learn
something from this difference?
- Sometimes I see a spike in the usage of those values, e.g.
I can find out about volumes if I turn the debug level of the
fileserver processes up 3 times, but this uses quite a bit of space
to leave turned on permanently. Is there some easy accessible data on
the (historic) distribution of callback on volumes?
I'd rather prefer not to increase -cb, since this seems to be not our
usual usage pattern.
Wed Apr 20 12:59:57 2016 We have run out of callback space; forcing
callback revocation. This suggests the
fileserver is configured with insufficient
callbacks; you probably want to increase the
-cb fileserver parameter (current setting:
1048576). The fileserver will continue to
operate, but this may indicate a severe
You can find a bit more of my thougts in
be aware - most of it is in german..
Andreas Hirczy <firstname.lastname@example.org> https://itp.tugraz.at/~ahi/
Graz University of Technology phone: +43/316/873- 8190
Institute of Theoretical and Computational Physics fax: +43/316/873-10 8190
Petersgasse 16, A-8010 Graz mobile: +43/664/859 23 57