zfs, nfs and zil

[Alexander Leidinger]

Quoting Claus Guttesen <kometen at gmail.com> (from Mon, 28 Mar 2011  
13:22:00 +0200):

> I've setup a server with FreeBSD 8.2 (prerelase) and patched zfs to
> ver. 28. The server has 11 disks each 2 TB in raidz2. The performance
> is very good and I've got approx. 117 MB/s on plain GB nics using
> iscsi.
>
> 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).

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.

Bye,
Alexander.

-- 
I'll eat ANYTHING that's BRIGHT BLUE!!

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