Date: Tue, 11 Apr 2006 15:41:45 +0200 From: Nicolas KOWALSKI <Nicolas.Kowalski@imag.fr> To: freebsd-fs@FreeBSD.org Subject: Re: [patch] giant-less quotas for UFS Message-ID: <vqoacasut46.fsf@corbeau.imag.fr> In-Reply-To: <443B8EC1.8080004@centtech.com> References: <20060329152608.GB1375@deviant.kiev.zoral.com.ua> <vqoy7ydv7lw.fsf@corbeau.imag.fr> <20060410144904.GC1408@deviant.kiev.zoral.com.ua> <vqou091v3vt.fsf@corbeau.imag.fr> <443A7C8E.4020203@centtech.com> <vqopsjpv2ci.fsf@corbeau.imag.fr> <443A8842.6060802@centtech.com> <vqolkudv09k.fsf@corbeau.imag.fr> <443A97F9.8090601@centtech.com> <vqoek04vbap.fsf@corbeau.imag.fr> <443B8EC1.8080004@centtech.com>
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Eric Anderson <anderson@centtech.com> writes: > Nicolas KOWALSKI wrote: >> Eric Anderson <anderson@centtech.com> writes: >> >>> Nicolas KOWALSKI wrote: >>>> Eric Anderson <anderson@centtech.com> writes: >>>> >>>>> Nicolas KOWALSKI wrote: >>>>>> Yes, this is exactly what is happening. To add some precision, some >>>>>> students here use calculation applications >>>>>> that allocate a lot of disk space, ususally more than their allowed >>>>>> home quotas; when by error they launch these apps in their home >>>>>> directories, instead of their workstation dedicated space, it makes >>>>>> the server go to its knees on the NFS client side. >>>>> When you say 'to it's knees' - what do you mean exactly? How many >>>>> clients do you have, how much memory is on the server, and how many >>>>> nfsd threads are you using? What kind of load average do you see >>>>> during this (on the server)? >>>> Sorry for the imprecision. >>>> The server is a Dual-Xeon 2.8Ghz, 2GB of RAM, using SCSI3 Ultra320 >>>> 76GB disks and controller. It is accessed by NFS from ~100 Unix >>>> (Linux, Solaris) clients, and by Samba from ~15 Windows XP. The >>>> network connection is GB ethernet. >>>> During slowdowns, it's only from a NFS client view that the server >>>> does not respond. For example, a simple 'ls' in my home directory is >>>> almost immediate, but when it slows down, it can take up to 2 minutes. >>>> On the server, the load average goes to 0.5, compared to a default >>>> maximum of 0.15-0.20. The nfsd processus shows them in the state >>>> "biowr" in top, but nothing is really written, because the quotas >>>> system block any further writes to the user exceeding her/his quotas. >>>> >>> In this case (which is what I suspected), try bumping up your nfsd >>> threads to 128. I set mine very high (I have around 1000 clients), >>> and I can say there aren't really ill-effects besides a bit of memory >>> usage (which you have plenty of). I suspect increasing the threads >>> will neutralize this problem for you. >> Using 128 nfsd threads, I stressed the server, by running on a NFS >> client a small C program, writting continuously in a file, so that the >> user "biguser" (account stored on /export/home2) exceeds his quota. >> It half-works: during the test, users working on another disk >> (/export/home) did not see any difference, but users working on the >> same disk that "biguser" (/export/home2) where almost halted. >> So, this is better, because before everybody was halted, but there is >> still a problem. >> Any other tips ? > > Watch gstat during the testing, and see if the disk that holds the > full partition is really busy. I'm betting it's thrashing the disk > continually checking for free space. I don't think there's any way to > avoid that. Mh, I did not find this "gstat" tool on the system or in the ports; perhaps is it in >= 5.x ? (the server is running 4.11-p15). It is sad I can not do anything about it: such a server pulled down by a single NFS-client. :-( However, Many Thanks for your help and tips. Best regards, -- Nicolas
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