Hi,

 

I am rebuiling my Disk 11 (old 3TB, new 4TB) at the moment. The rebuild began last night with the expected ~80MB/s and was due to complete in 13 or so hours.

 

When I looked at that status this morning the rebuild was at 50% but the speed dropped to ~2MB/s with a time to complete in 8 days.

 

I never had this before and wonder what to do about it.

 

syslog is free of any related error as far as I can tell. The SMART report of the new drive does not show anything either.

 

I am attaching the diagnostics file and welcome your kind advice on how to proceed.

 

Thanks!

 

Tazman

ss-diagnostics-20191015-0528.zip

Edited October 17, 20196 yr by tazman
spelling, solved

1 hour ago, tazman said:

syslog is free of any related error as far as I can tell

Also don't see anything that explains the slowdown, could be a slow sector zone on one of the disks, if it doesn't get better in an hour or two you can also try rebooting, but it will start from the beginning.

Thanks, Johnnie. The speed view shows all drives reading and writing at about the same speed. Does this tell us something?

.

That is not going to help much as the rebuild cannot happen faster than the slowest disk.

 

Using something like the DiskSpeed docker container would be one way to check out the performance of individual drives.

34 minutes ago, itimpi said:

That is not going to help much as the rebuild cannot happen faster than the slowest disk.

 

Using something like the DiskSpeed docker container would be one way to check out the performance of individual drives.

I ran DiskSpeed a few month ago, it's very insightful. The now to be replaced Disk 11 was actually the slowest in the pack.

 

So do I understand you right that most likely one of the other disks might be slowing down the entire process?

3 minutes ago, tazman said:

So do I understand you right that most likely one of the other disks might be slowing down the entire process?

That was what I was thinking.   It might be worth making a note of the current point reached as that could act as a guide to which section of the DiskSpeed graphs are most likely to be relevant.

Just an interim status: I paused the Rebuild and ran DriveSpeed. It's stalling with my Parity 2 drive at about 800Mb. Running an extended SMART test on that drive now.

The extended SMART test on the partity 2 drive completed without errors. I then restarted the rebuild and it continued with the normal speed. The read speeds which showed around 4.5MB in the picture above increased to ~75 and the write speed to ~65.

 

After the rebuild was complete I ran DiskSpeed again and it did complete for all drives.

 

Although I obviously like the fact, that it fixed itself, I will keep Parity 2 on close watch.

Edited October 17, 20196 yr by tazman
added new read speeds