Prioritize resilvering priority

[javocado]

Thanks for all that feedback. Yes, this is for zfs. It looks like some of
those sysctls are not available in 8.3:

# sysctl vfs.zfs.scrub_delay
sysctl: unknown oid 'vfs.zfs.scrub_delay'

# sysctl vfs.zfs.resilver_delay
sysctl: unknown oid 'vfs.zfs.resilver_delay'

# sysctl vfs.zfs.zfs_top_maxinflight
sysctl: unknown oid 'vfs.zfs.zfs_top_maxinflight'


But I do have:
vfs.zfs.vdev.max_pending: 10 (dynamic)
vfs.zfs.scrub_limit: 10 (loader)

So, I think I would want to lower one or both of these to increase I/O
responsiveness on the system. Correct? How would the 2 play together in
terms of which to adjust to achieve the best system performance at the
expense of a longer resilver?


On Tue, Jul 21, 2015 at 5:32 PM, Gary Palmer <gpalmer at freebsd.org> wrote:

> On Tue, Jul 21, 2015 at 04:06:05PM -0700, javocado wrote:
> > Hi,
> >
> > How does one go about prioritizing the resilvering process so it does not
> > overwhelm normal disk I/O on a FreeBSD (8.3amd) system?  Further, can
> this
> > be altered in real time, or do the settings have to be in place prior to
> > the resilvering even starting?
>
> You don't state, but is this on ZFS?
>
> I assume they're on 8.3 also, but look at settings like
> vfs.zfs.resilver_min_time_ms and vfs.zfs.resilver_delay in sysctl.
> Searching for resilver_min_time_ms and resilver_delay may give
> some hints, e.g.
>
>
> http://broken.net/uncategorized/zfs-performance-tuning-for-scrubs-and-resilvers/
>
> does the opposite to what you want, but it should give hints.  Also
>
>
> https://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/zfs-advanced.html
>
> I think they're dynamic.  I tuned the scrub settings and they took effect
> immediately.
>
> Regards,
>
> Gary
>