Does FreeBSD's ZFS reserve 1/64 of the capacity for COW?

[krad]

I wouldnt really worry about it as you shouldnt be planning to go over 80%
capacity on a production pool anyhow, as at some point after that, and way
before 100% you will start to get big slowdown on writes, which is more of
an issue.


On 6 December 2013 12:46, Trond Endrestøl <
Trond.Endrestol at fagskolen.gjovik.no> wrote:

> Hi,
>
> Today I came across "Becoming a ZFS Ninja Part 1"
> http://www.youtube.com/watch?v=tPsV_8k-aVU featuring Ben Rockwood who
> stated that ZFS reserves 1/64 of the capacity for COW safe-guarding.
> Fast forward to 00:49:44. Thus, one should take this fact into account
> when planning the storage capacity of your (larger) zpools.
>
> Does FreeBSD's ZFS also reserve 1/64 of the capacity for COW?
>
> If it's true, then I guess this should be noted in zpool(8) and in the
> Handbook.
>
> Any comments or insights?
> Do you think I should file a PR?
>
> Have a nice weekend! ;-)
>
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