Extremely slow (~1MB/s) parity check

[bmonroe1]

I'm doing a parity check, and it's running extremely slow. Right now the end date is 40 days. I remember running into this once before. I think what solved it last time was cancelling the check, shutting down, and starting up as a new config with a fresh UnRAID install on the USB. I'd like to avoid doing that if possible. Any idea what could be causing this? The check did find a few sync errors (up to 40 now), but it's been slow before and after correcting the errors, so I don't think they are the sole cause. Also, SMART status on all drives is good, and they are all <1yr old WD Reds, so I don't think it's drive failure either. Frankly, I'm at a loss. Thoughts?

Diagnostics attached.

lcars-diagnostics-20180503-1947.zip

[John_M]

I agree your SMART reports look good with just a few signs of cable problems in the past. Your syslog is difficult to read in places because it's spammed by the Preclear plugin and a USB error. You have a mouse attached that keeps disappearing and reappearing at about a 50 second interval. I notice a load average of 48, which is high even for a system with eight cores. I see a number of b2sum processes in the D state (waiting for I/O) so it looks as though the Dynamix File Integrity plugin is busy doing its checksum verification. You can configure it not to run when a parity check is underway. Docker activity may also be contributing to the disk I/O load.

[bmonroe1]

I've never used the Preclear plugin, I just heard it was a good idea so I installed it. Should I just delete it? Also, I can unplug the USB devices. I was keeping a mouse and keyboard plugged in for troubleshooting, but obviously they aren't a help right now. Yeah, not sure what's up with the loading. It's a Ryzen 7 so it's been able to chew up HEVC streams on Plex like nothing, yet it's now sitting idle at ~50%. I'll delete the file integrity plugin for now too. 

 

What should I get you to see if any of the above helped? Run diagnostics again? Something else? 

 

Thanks for your help so far! 

[bmonroe1]

Removed the two plugins, pulled the mouse and keyboard, and parity check speed jumped to ~25MB/s! So, huge improvement, but still suspiciously slow. Usually averages ~80MB/s, with spikes to 110. 

 

So you've solved my immediate problem of the parity check completing in a reasonable timeframe (thank you!), but I still think something is less-than-ideal. Thoughts?

[John_M]

Certainly delete the Preclear plugin if you don't use it. The keyboard is fine but if you need the mouse try another socket. You don't need to delete the File Integrity plugin if you find it useful. I use it but I don't allow it to run its verification process during a parity check.

 

The parity errors are a worry, not least because they are in two contiguous blocks. That isn't right. Zero parity errors is the only acceptable number.

 

One thing you should try is to reboot into safe mode. Don't start any dockers or VMs and run a parity check. See how it goes.

[bmonroe1]

I'll give that a try. Thanks!