Slowest Drive 50Mb/s, Parity check maxes about 3MB/s

[RealActorRob]

No errors, drives bench way fast, total drive throughput is about 35-40 max.

 

11 days projected to complete, largest drive 4tb. No SMR.

 

For some reason two of my drives are slow at 50ish each (will address that) but there's no reason I can find for a sub 4Mb/s parity check.

 

Controller links at 4GB/s.

 

Diags attached.

 

 

 

blacktower-diagnostics-20231130-0037.zip

[JorgeB]

There's something writing to disk6 and reading from other disks, stop all the array activity and speed should increase by a lot.

[itimpi]

9 minutes ago, JorgeB said:

There's something writing to disk6 and reading from other disks, stop all the array activity and speed should increase by a lot.

The writing to disk6 is likely the culprit as the writes to that drive corresponds to the number of writes to the parity drives,   The reading from other drives is probably just a consequence of the parity check running.

[RealActorRob]

 

Still slow, but still don't see how they should be this slow.

 

Only one bench didn't have a steady curve from Diskspeed, one of the parities. 

 

I watched it for a bit and never saw it peak over maybe 30 on one for a few seconds.

 

 

Here's total throughput and something weird on reads:

Obviously this isn't correct but maybe a clue?

 

And I don't see how disk speed benches ok and then the parity check crawls, haven't had a fast one since March.

 

 

And that's across the board slow not just sections of some disk.

 

Real head scratcher.

 

[RealActorRob]

@itimpi Disk 6 seems a little wonky but here's diskspeed, ran just now DURING the parity check. It's getting pretty old, at over 7 years but SMART values are all 0 not even a CRC error. Cool at 40C as well. 

 

 

Edited November 30, 2023 by RealActorRob

[JorgeB]

It's likely disk6 limiting the speed, though there appear to still be some small writes to the array going on.

[RealActorRob]

Yeah, I'm looking for a good price on a drive...might get a lightly used datacenter large drive then replace it with one of the 4TB parity drives.

 

Worst case if it fails I have a 4TB SMR or just swap them back...plus i can tolerate 2 fails.

 

Note @JorgeB that I also changed the CPU governeor to 'on demand' and it's a bit faster tho it wasn't being pushed before anyway.

 

Edited November 30, 2023 by RealActorRob