Date: Mon, 18 Jan 2010 21:34:54 +0100 From: =?ISO-8859-15?Q?Morgan_Wesstr=F6m?= <freebsd-questions@pp.dyndns.biz> To: "O. Hartmann" <ohartman@mail.zedat.fu-berlin.de> Cc: FreeBSD Stable <freebsd-stable@freebsd.org>, freebsd-questions@freebsd.org Subject: Re: immense delayed write to file system (ZFS and UFS2), performance issues Message-ID: <4B54C5EE.5070305@pp.dyndns.biz> In-Reply-To: <4B54C100.9080906@mail.zedat.fu-berlin.de> References: <4B54C100.9080906@mail.zedat.fu-berlin.de>
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O. Hartmann wrote: > I realise a strange behaviour of several FreeBSD 8.0-STABLE/amd64 boxes. > All boxes have the most recent STABLE. One box is a UP system, two > others SMP boxes, one with a Q6600 4-core, another XEON with 2x 4-cores > (Dell Poweredge III). > > Symptome: All boxes have ZFS and UFS2 filesystems. Since two weeks or > so, sometimes the I/O performance drops massively when doing 'svn > update', 'make world' or even 'make kernel'. It doesn't matter what > memory and how many cpu the box has, it get stuck for several seconds > and freezing. On the UP box, this is sometimes for 10 - 20 seconds. > A very interesting phenomenon is the massively delayed file writing on > ZFS filesystems I realise. Editing a file in 'vi' running on one XTerm > and having in another Xterminal my shell for compiling this file, it > takes sometimes up to 20 seconds to get the file updated after it has > been written. It's like having an old, slow NFS connection with long > cache delays. > These massively delayed file transactions are not necessarely under > heavy load, sometimes they occur in a relaxed situation. They seem to > occur much more often on the UP box than on the SMP boxes, but this > strange phenomenon also occur on the Dell Poweredge II, which has 16GB > RAM and summa summarum 16 cores. This phenomenon does occur on ZFS- and > UFS2 filesystems as well. It is hardly reproducable. > > Is there any known issue? > > Ragrds, > Oliver The disks involved don't happen to be Western Digital Green Power disks, do they? The Intelli-Park function in these disks are wrecking havoc with I/O in Linux-land at least, causing massive stalls and iowait through the roof during the 25-30 seconds it takes for the heads to unload after parking. I have two of these disks sitting on my desk now collecting dust... /Morgan
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