Setting "zfs_arc_max" value in FreeBSD 8.

[jhell]

On Fri, 22 Jan 2010 11:47, fbsdlist@ wrote:
>>> Anyone know if it is adjustable on a system with 1024MB of ram ? Is this
>>> just being auto calculated by some other value ?
>
> You may want to make sure that vm.kmem_size is set to a value much
> larger than vfs.zfs.arc_max. Default value may be too small to allow
> such a large ARC.
>
> On a side note, I'm not sure that ZFS is a good match for system with
> only 1G of RAM. By trial and error on my box with 8G or memory I've
> figured out that I need to set arc_max ~1G below physical memory size
> to avoid lockups under load. YMMV.
>

ZFS on this box with 1G has been quite enjoyable actually. With the 
settings I have posted I have not had any lockup on stable/7 and no sudden 
freezes or waits for transfers. So this entirely thus far has been a 
godsend. I had even put this thing through some of the tortures that 
others have posted to the list and not come up with the same results but 
better. There is obviously a lot of variables in this between hardware and 
configurations used so the results are minimal in comparison. With ZFS in 
place on this machine it performs a little bit under specs for the 
hardware but I wouldn't expect anything less for such a file-system.

-- 

  Thoughts & Prayers out to Haiti.

  jhell