Date: Mon, 28 Mar 2011 18:46:56 +0200 From: Claus Guttesen <kometen@gmail.com> To: Alexander Leidinger <Alexander@leidinger.net>, FreeBSD Stable <freebsd-stable@freebsd.org> Subject: Re: zfs, nfs and zil Message-ID: <BANLkTiknikVSS_aRRwFEVXAcWx=Aqk9WZg@mail.gmail.com> In-Reply-To: <20110328164113.70512us1tv7w5gcg@webmail.leidinger.net> References: <BANLkTinZvLDkmUNHmDGQpQFRr31s=hyHuQ@mail.gmail.com> <20110328164113.70512us1tv7w5gcg@webmail.leidinger.net>
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>> I'm mounting the FreeBSD-server from a couple of vmware esxi 4.1 >> servers using nfs, but when there is alot of i/o the server becomes >> unresponsive, easily triggered by installing ie. ms-sql. The server >> itself is up but is not reachable from the network. When I take the >> nic down and up again connection to the network is reestablished >> (ip-wise). >> >> A friend of mine has suggested that I disable the zil. The page >> http://wiki.freebsd.org/ZFSTuningGuide says 'Disabling ZIL is not >> recommended where data consistency is required (such as database >> servers) but will not result in file system corruption.' >> >> Has anyone tried to disable zil and achieved better performance and >> still maintain a consistent filesystem? > > The ZIL is not linked to NIC down/up events. It is a completely different > topic. I suggest to find the real problem instead of doing some random > tuning (which is not tuning in this case but foot-shooting). I'm aware of that, but the only way the problem shows up is when a windows machine performs an installation or a windows update (and has alot of updates in the pipeline). When traffic (i/o) is low to moderate it justs goes along without any issues. And if the same virtual windows-installation is on an iscsi-partition (mounted by the vmware-server) I can't reproduce the problem. So if disabling the zil did make a difference I would install a dedicated zil-ssd-device. And if that did alleviate my problem the issue could be related to windows performing alot of small reads and writes. Hence why I wanted to disable the zil. > FYI: disabling the ZIL is someting to do if you are desperate, do not care > about production incidents, and everything else (if the ZIL is the problem > -- which most probably it isn't by reading your message -- a (maybe write > optimized) SSD as a log device could be a solution) does not solve the > issue. Thank you for your input. I will get a ssd-drive. -- regards Claus When lenity and cruelty play for a kingdom, the gentler gamester is the soonest winner. Shakespeare twitter.com/kometen
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