Speeding up resilvering

[Matthew Seaman]

Hi,

I've a zpool which is taking an inordinately long time to resilver and
replace a device.  It had only got to about 8% completion after a day,
implying over a week to resilver about 6TB data.

Now, I've applied the resilver performance tuning sysctls from
https://wiki.freebsd.org/ZFSTuningGuide:

vfs.zfs.scrub_delay=0
vfs.zfs.top_maxinflight=128
vfs.zfs.resilver_min_time_ms=5000
vfs.zfs.resilver_delay=0

but it doesn't seem to have made a great deal of difference.  Most of
the benefit there would apparently come from reducing scrub_delay or
resilver_delay -- but this system is only booted to single user mode, so
the drives are otherwise idle and the resilver should have automatically
switched to running full throttle anyhow.

Given the machine is not going to be doing anything else other than
resilvering for the time being, is there any more aggressive tuning or
tricks to get it to go faster that people would recommend?

	Cheers,

	Matthew

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