Speeding up resilvering

[Matthew Seaman]

On 07/08/15 17:37, Karl Denninger wrote:
> Be aware that when a resilver /starts /it does a number of very small
> and diverse I/O operations.  Throughput during that time _*stinks*_, and
> as a result in the first few minutes to half-hour or so (with a very
> large vdev) you will see utterly ridiculous projections of completion time.
> 
> Once that part of the process completes (usually within a few minutes on
> modest to moderate size vdevs, but it will be longer on very large ones)
> the performance level of the resilver will go up a lot and the projected
> completion time will become far more reasonable.

Yeah.  This resilver has been running for over a day already, and it is
refusing to project what the finishing time will be, mostly because I
had to yank it out of the DC in order to substitute another machine to
do what this one should have been doing.  (So it spent a night powered
down in he middle of the resilver operation.)

The VDEV is about 20TB which I suppose is pretty big, but possibly not
what some ZFS practicioners would call "very large..."  6 x 4TB drives
in a RAIDZ

	Cheers,

	Matthew





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