On Apr 20, 2016, at 11:54 AM, Andreas Hirczy <a...@itp.tugraz.at> wrote: > In that context 3 questions regarding nFEs and nCBs entered my mind: > > - What's the meaning of those?
nFEs is the number of FileEntry table entries currently in use by the fileserver. One entry is used for each unique file (vnode) the fileserver has given callbacks for. nCBs is the number of CallBack table entries currently in use by the fileserver. One entry is used for each callback the fileserver has given out. nblks is the total size (number of slots) in each table, as set by the fileserver -cb parm. > - I found some information about nFEs and nCBs in > > <https://www.openafs.org/pages/newsletter/newsletter-2013-03-volume004-issue05.html#openafs_tuning__part_i__fileservers__general>: > "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. This is correct. > Should I consider to store just "max(nFEs, nCBs)" or can I learn > something from this difference? You could store both; often a single file may have multiple callbacks. > - Sometimes I see a spike in the usage of those values, e.g. > <https://itp.tugraz.at/~ahi/privat/OpenAFS/graph_nCBs_2016-04-20.png> > 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? You could use the fileserver -auditlog to track accesses by fid (which includes the volume id). Or for grand totals, you can continue to store the information you are getting from xstat_fs_test. > 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 > performance problem The GetSomeSpace_r routine issues this log message; it is only called when either the CB or FE freelist is exhausted (that is, the count has reached nblks). This routine also increments the GotSomeSpaces counter, which is in the same xstat_fs_test collection as nCBs, nFEs, and nblks. If you are running close to the edge on callbacks, you should definitely track that counter, and ideally you want it to always remain zero. Regards, -- Mark Vitale Sine Nomine Associates _______________________________________________ OpenAFS-info mailing list OpenAFS-info@openafs.org https://lists.openafs.org/mailman/listinfo/openafs-info
