No more free space after upgrading to 10.1 and zpool upgrade

Andriy Gapon avg at
Wed Nov 19 11:09:36 UTC 2014

On 19/11/2014 06:13, Steven Hartland wrote:
> The new space map code should help with that and a fixed 3.125% is a large
> portion of a decent sized pool.
> On our event cache box for example thats 256GB which feels like silly amount to
> reserve.
> Does anyone have any stats which backup the need for this amount of free space
> on large pool arrays, specifically with spacemaps enabled?

There was a presentation about the spacemap code at the OpenZFS Devsummit.
One point is that going above 95% will kill performance (actually sooner).  This
is applicable to all spacemap algorithms currently available.

There is a pretty graph at page 13 here
Andriy Gapon

More information about the freebsd-fs mailing list