Slow Parity Sync

[VonHex]

I know you have probably all see this a bunch but im having issues with slow parity syncing. When Docker is disabled it runs around 39mb/s so with a 5tb drive it takes about 2 days to finish, but when Docker is running it drops to around 7mb/s and says it will take 25 days to complete, is this normal? Drive is working fine and speed test puts it around 150mb/s. Any help would be appreciated!

genysis-diagnostics-20220707-1659.zip

[JorgeB]

7 hours ago, VonHex said:

but when Docker is running it drops to around 7mb/s

Depends on what the dockers are doing, just having the docker service enabled should not slow down, but if some container is reading or writing a disk it will.

[VonHex]

Hmm that makes sense. Is the 38mb/s for a 5tb disk normal?

[JorgeB]

11 minutes ago, VonHex said:

Is the 38mb/s for a 5tb disk normal?

Not really, but you are have some USB disks in the array, those are not recommended, and not just for performance reasons, you can use the diskspeed docker to benchmark your disks/controllers.

[VonHex]

Hmm, besides the usbs they all read around 150, besides the ssds that are around 500. 

[JorgeB]

Yes, but parity check can only go as fast as the slowest disk at that position.

[VonHex]

Ah I see, that makes sense! Thanks!

[Videodr0me]

There are also some other potential bottlenecks/pitfalls:

1) on low cpu powered servers dual parity might be cpu contrained. On my Intel® Atom™ CPU C3538 @ 2.10GHz unraid server going from single to dual more than halved parity speed

2) make sure the cpu scaling governor is set to performance (tipps and tweaks plug-in). This can also make a big difference

3) on systems with a high number of drives the i/o performance of the disk controllers and or number of available pci lanes can make a difference

4) check and optimize the tunables under disk settings - there are a number of threads in the forum give information about this

5) if you use usb drives, make sure that all drives really use > usb 3.0. Because if only one drive falls back to usb 2.0 it completely limits the parity speed.

 

 

[VonHex]

I'll look into this! That's great, thanks for the tips!