ZFS performance as the FS fills up?

[Tom Evans]

On Wed, Mar 9, 2011 at 12:51 PM, Jeremy Chadwick
<freebsd at jdc.parodius.com> wrote:
>
> Otherwise, I can imagine that prefetching could cause what you describe,
> which is enabled by default in 8.0 and 8.1 and auto-disables in 8.2 if
> the amount of available memory is less than 4GB.
>

I don't think this is accurate. Prefetch was certainly disabled by
default on 8.0 if you had 4GB of RAM or less, requiring the sysctl
vfs.zfs.prefetch_disable=0 to be set if you wanted prefetch and had
4GB of RAM or less.

Cheers

Tom