Messages in this thread | | | Date | Fri, 25 Apr 2003 01:57:30 -0300 | From | Christian Reis <> | Subject | Re: NFS client locking hangs for period |
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Well, since I've more or less moved on from my original problems, I should probably post a summary of what was going on, and what I did to work around it.
Details can be read out from [1]: after a certain amount of time a number diskless clients, which were mounting everything from the same NFS server, started getting hung lock requests from the server. The server ran 2.4.20, reiserfs over RAID-1 mounted with 2 SCSI disks on an Adaptec 29160. The clients were debian woodys running 2.4.20.
Our diskless setup is a bit unusual: all the clients mount the same root partition. I tried to be very careful to make sure no files were written to on /, but I never got to the point where the clients could mount the directory read-only. I used devfs to make sure that the /dev directories were `localized' and syslog/console ownership and permissions kept sane.
The locking problem, however, was not related to the root filesystem -- it seems to have happened with files on the /var/log mount, which is separate for each box (but still coming from a shared filesystem /export/root on the server, which contains all the client directories). If I mounted /var/log with the nolock option, they ran fine. This took me a very long time to figure out, and I'd advise anyone with locking problems to give it a go.
I should point out that this *does* seem to be a bug in the NFS server code. I think it is associated with reiserfs, being that I haven't seen it happen on other partition types. Rebooting the server cleared up the problem. Erasing or changing files in /var/lib/nfs did not. While I was initially using a volatile /var/lib/nfs directory on the *clients*, I changed this on Trond's suggestion [2]. It did not fix the problem.
However, since I know little about the code itself, and it's not very clear how one should debug, I was unable to pinpoint the exact source of the problem, which very much saddens me. The workaround, however, was quite effective.
[1] http://groups.google.com/groups?hl=en&lr=&ie=UTF-8&th=9db70994c3458f46&rnum=1 [2] http://groups.google.com/groups?q=christian+reis+nfs+locking&hl=en&lr=&ie=UTF-8&scoring=d&selm=20030126231006%246e11%40gated-at.bofh.it&rnum=3
Take care, -- Christian Reis, Senior Engineer, Async Open Source, Brazil. http://async.com.br/~kiko/ | [+55 16] 261 2331 | NMFL - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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