Slow Disk Speed - 60 Hours Parity Check

[teaguecl]

I have an Unraid machine I built in 2013 that has served my needs pretty well.  It has always been slow, but I didn't think there was anything wrong until recently.  I use it to stream movies to my TV over a local network, and it's been plenty fast for that until recently when I upgraded to 4K content which causes buffering.

What really worries me is the parity check speed.  My setup spends 3-4 days every month doing parity (60 hours, average speed is ~50 MB/sec).  I didn't realize that was abnormal until I read a thread recently where everyone else thinks 12 hours is a long time and have average speeds in the 100-200 MB/sec range.  During a parity check the array is basically unusable it's so slow (which is normal) - but having my array be inaccessible for 3 days every month is a pain.

I built my server with meager specs, but I'm not sure if that's the culprit.  RAM doesn't seem to be maxed out, and CPU isn't either.  One of the CPU cores spikes up to 80-95% every few seconds - so maybe it's single core performance that is hurting me?

 

Does anyone know why my parity speeds would be so low?  They are usually 30MB/sec for the first 4TB, they go up to 40MB/sec up to 8TB and 70MB/sec beyond that.

 

I've attached some screenshots of my setup.

 

 

 

 

[Squid]

You should post your diagnostics

[teaguecl]

Thanks Squid for the reminder.  Diagnostics are attached here.

tower-diagnostics-20220303-1634.zip

[itimpi]

6 hours ago, teaguecl said:

During a parity check the array is basically unusable it's so slow (which is normal) - but having my array be inaccessible for 3 days every month is a pain.

Regardless of whether you sort out the parity speed issue you might want to consider installing the Parity Chevk Tuning plugin so you can trade off elapsed time for the check for avoiding it impacting daily use of the server.

[JorgeB]

Change the onboard controller from IDE to AHCI/RAID.

[teaguecl]

Thanks for the help.  I switched the BIOS setting from IDE to AHCI and things are looking much better.  DiskSpeed results don't look much different, but I started a parity check and it was going at 90MB/sec.  That's about 3x faster than before, and brings the parity check time down to about 24 hours - which is great!