On Thu, May 9, 2019 at 5:37 AM Miroslav Lachman <000.fbsd at quip.cz>
wrote:>
> Dimitry Andric wrote on 2019/05/09 13:02:
> > On 9 May 2019, at 10:32, Miroslav Lachman <000.fbsd at quip.cz>
wrote:
>
> [...]
>
> >> Disks are OK, monitored by smartmontools. There is nothing odd,
just the long long scrubs. This machine was started with 4x 1TB (now 4x 4TB) and
scrub was slow with 1TB disks too. This machine - HP ML110 G8) was my first
machine with ZFS. If I remember it well it was FreeBSD 7.0, now running 11.2.
Scrub was / is always about one week. (I tried some sysctl tuning without much
gain)
> >
> > Unfortunately https://svnweb.freebsd.org/changeset/base/339034, which
> > greatly speeds up scrubs and resilvers, was not in 11.2 (since it was
> > cut at r334458).
> >
> > If you could update to a more recent snapshot, or try the upcoming
11.3
> > prereleases, you will hopefully see much shorter scrub times.
>
> Thank you. I will try 11-STABLE / 11.3-PRERELEASE soon and let you know
> about the difference.
>
> Kind regards
> Miroslav Lachman
On 11.3 and even much older releases, you can greatly speed up scrub
and resilver by tweaking some sysctls. If you have spinning rust,
raise vfs.zfs.top_maxinflight so they'll do fewer seeks. I used to
set it to 8192 on machines with 32GB of RAM. Raising
vfs.zfs.resilver_min_time_ms to 5000 helps a little, too.
-Alan