One last data point on this from a larger pool, 11 disk raid5 pool
(raid1 metadata), this is probably not a very recommended
configuration but it's a 3rd backup and mostly for testing raid5 on a
larger pool:
UUID: 1236acc8-dbd5-41bd-bf3d-872a8fbbce49
Scrub started: Sun Dec 15 11:23:45 2019
Status: running
Duration: 0:51:34
Time left: 90:06:52
ETA: Thu Dec 19 06:22:13 2019
Total to scrub: 18.10TiB
Bytes scrubbed: 175.12GiB
Rate: 57.96MiB/s
Error summary: no errors found
Same pool during a btrfs send to /dev/null:
btrfs send /mnt/disks/Pics/T12_disk1_Pics_2019-12-15-0829/ | pv -bart
> /dev/null
At subvol /mnt/disks/Pics/T12_disk1_Pics_2019-12-15-0829/
447GiB 0:13:19 [ 635MiB/s] [ 573MiB/s]
^ ^
cur. spd / avg. spd
So looks to me like scrub performance is around 1/10 of what it should
be, and not optimal to wait multiple days to scrub a larger pool.
Jorge
