On Thu, May 7, 2020 at 10:42 PM Andrew Pam <andrew@xxxxxxxxxxxxxx> wrote: > > On 8/5/20 2:21 pm, Chris Murphy wrote: > > What does 'iotop -d 10 -o' report? I'm expecting around 300MB/s reads. > > 91872 idle root 149.25 M/s 0.00 B/s 0.00 % 0.00 % btrfs scrub > resume -c3 /home > 91873 idle root 157.77 M/s 0.00 B/s 0.00 % 0.00 % btrfs scrub > resume -c3 /home > > > The ETA is +14 hours what you posted 21 hours ago. So yeah that's > > fakaked, but at least it's not saying it'll be done in year 5544! > > I did cancel when I went to bed and resumed when I got up three hours > later on two occasions, so subtract six hours. > > > I've always seen the ETAs be pretty accurate so I don't know what's going on. > > Maybe it screws up once you cancel and resume too many times? > > > 3082813.44MB to go divided by 300MB/s is 171 minutes. Or just under 3 > > hours. So the time left / ETA is wrong based on this rate, if it's a > > stable rate, which it might not be. > > I have an I/O load graph on my screen and it shows 100% read load on > both drives at all times, with an I/O rate of around 130-160 M/s per drive. > > > What are the current mount options for this file system? > > /dev/sda on /home type btrfs > (rw,noatime,space_cache,autodefrag,subvolid=5,subvol=/) > > Thanks, > Andrew I don't know if space_cache v1 can negatively impact scrubs but it does negatively impact other things especially on larger file systems with a lot of free space remaining. v1 cache exists as data blocks, v2 cache is a dedicated 'free space tree' and resides in fs metadata. It's the inverse of the extent tree. A conservative approach that might speed things up: # mount -o remount,clear_cache,nospace_cache /mnt Once it's done: # mount -o remount,clear_cache,space_cache=v2 /mnt This sets a feature flag, and the next time you mount normally, it'll use v2. You could do this now during the scrub, but it might slow it down a bit while the new cache is being created. If the file system isn't busy it might take a minute to build. Anyway, I'm pretty confident this scrub will finish in about 2.5 hours if you just leave it as is. -- Chris Murphy
