No more free space after upgrading to 10.1 and zpool upgrade
Andriy Gapon
avg at FreeBSD.org
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
http://open-zfs.org/w/images/3/31/Performance-George_Wilson.pdf
--
Andriy Gapon
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