Hi guys -

 

I recently upgraded to v6 from 5.08RC that I started off on about 4 years ago. My parity checks on v6 though are extremely ridiculously slow. I'm getting ~ 1MB/s. On v5 I used to get at least 20-30 MB/s. Does anyone have any ideas as to what I should look at to begin diagnosing the problem? I've an AMD sempron 145 CPU and 4 gigs of memory. I haven't noticed a difference in write (~25 mb/s) or read (~70 mb/s) speeds. It's really just the parity check that's being this slow.

 

Something I noticed is that with v5.08, the lights on my hotswap cages were always on signifying that things were happening pretty much nonstop. When v6, the lights for each HDD blinks. It turns on for a microsecond and then stays off for a second or two. It appears as if v6 is rapidly spinning my disks up and down.

 

I've tried the usual turn it off and on again. But that's about the limit of my unraid debugging skills. Any help you guys can provide would be much appreciated. I don't want to go back to v5 because v6 looks awesome.

 

I've attached a syslog after my latest attempt at running a parity check (I turned it off after about 2 minutes). I have attempted to run it overnight in the hopes that the low speed is temporary and it'll fix itself but it doesn't and the slow speeds remain (sometimes even dropping to KB/s).

tower-syslog-20170204-2343.zip

v6 is far more CPU intensive than previous versions ... and your Sempron 145 is a very low-end CPU that (as you can tell) struggles with the demands of v6.  You should see some improvement if you disable display updates, but you aren't going to get the same parity check speeds you had with v5 no matter how you tweak the system.

 

I thought that but then noticed that the CPU usage wasn't even at 50%. Can it be something else?

It could indeed be something else -- your speed is VERY low ... far lower than even your Sempron should be able to support.

 

Are you getting any disk errors or sync errors during the parity test?

 

Not sure - how do I check that? A disk error would be pretty obvious wouldn't it - the disk icons would be red in the main unraid page.

Just look at the GUI => the Main tab shows the reads/writes/errors for each of the disks, and the current state of the parity check shows the number of sync errors

 

You're getting CRC errors on disk4 (and eventually got read errors), replace the SATA cable.

Thanks garycase and johnnie.black! Just noticed that. I'll see if there are lose connections somewhere and maybe find a spare SATA cable that hopefully fixes this.

Thanks, that seems to have fixed it! Appreciate y'alls help.