Scrub incredibly slow with 13.0-RC3 (as well as RC1 & 2)

[Andriy Gapon]

On 25/03/2021 10:55, Matt Churchyard wrote:
> Just an a aside, I did post a message a few weeks ago with a similar problem
> on 13 (as well as snapshot issues). Scrub seemed ok for a short while, but
> then ground to a halt. It would take 10+ minutes to go 0.01%, with everything
> appearing fairly idle. I finally gave up and stopped it after about 20 hours.
> Moving to 12.2 and
> rebuilding the pool,

This could make a huge difference, though.
Scrub performance significantly depends on the data layout.
The more sequential it is the better.
So, older (and more fragmented) pools are at disadvantage.

> the system scrubbed the same data in
> an hour, and I've just scrubbed the same system after a month of use with
> about 4 times the data in 3 hours 20. As far as I'm aware, both should be
> using effectively the same "new" scrub code.
> 
> Will be interesting if you find a cause as I didn't get any response to what
> for me was a complete showstopper for moving to 13.


-- 
Andriy Gapon

-- 
Andriy Gapon