ZFS - abysmal performance with samba since upgrade to
freebsd at jdc.parodius.com
Thu Feb 24 22:49:56 UTC 2011
On Thu, Feb 24, 2011 at 07:23:54PM +0100, Christer Solskogen wrote:
> On Thu, Feb 24, 2011 at 8:55 AM, Jeremy Chadwick
> <freebsd at jdc.parodius.com> wrote:
> > # Set TXG write limit to a lower threshold. This helps "level out"
> > # the throughput rate (see "zpool iostat"). A value of 256MB works well
> > # for systems with 4GB of RAM, while 1GB works well for us w/ 8GB on
> > # disks which have 64MB cache.
> > vfs.zfs.txg.write_limit_override=1073741824
> Sorry if you have said this before, but could you elaborate a bit
> about this number? For instance, how much does the cache on the disk
> has to say.
> In my case: 3x1.5TB raidz with WD15EADS-00R6B0 which has 32MB cache
> and 12GB memory. What would you recommend and why.
There's no real way to provide an in-depth analysis of this number; that
is to say, hard disk parameters (RPM, cache, and overall performance of
the drive (highly dependent upon on-disk firmware)) ultimately dictates
what's "best" for this number. I also imagine number of disks plays a
role as well This is why I advocate not messing with it unless you want
to try and "level out" throughput.
The value itself is literally 1024*1024*1024 (1GB). Don't think this is
some magic number; it's just what I came up with. You can search the
FreeBSD lists for references to the variable itself and find other
people advocating values like ~33MByte, etc.. All depends on how you
want the system to behave.
I don't particularly like watching the system behave like I described
(you snipped that portion of my text), which is why I use this variable.
| Jeremy Chadwick jdc at parodius.com |
| Parodius Networking http://www.parodius.com/ |
| UNIX Systems Administrator Mountain View, CA, USA |
| Making life hard for others since 1977. PGP 4BD6C0CB |
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