Hey All,

Running unRAID 5.0rc12a on a beefy workstation I had lying around (it's sole purpose right now is to preclear a bunch of drives I have incoming for a new unRAID server), and while the pre-clear read goes great (100-130MB/s), the moment it starts copying zero's to the remainder of the disk (step 2), I get such blazing fast speeds as.....479kB/s...I gave it another 10-12 hours after seeing those speeds and they never increased, I had reached maybe 1% progress.

 

I'm using WD Red 3TB drives (WD30EFRX), trying to preclear 3 drives at once. I have tried canceling two of the three clears, but the speed did not increase (ultimately ended up just restarting all 3 clears to see if they'd speed up the second attempt). This did not help, they are still running at that speed.

 

While I was expecting these drives to take 24-33 hours to clear, at the current speed I'm looking sometime in a month or two, which isn't ideal (I have 5 more drives coming for this build that I will need to get to heh).

 

I did a search of the forums, but unfortunately the only explanations i was finding for slow speeds with preclearing were failing drives kicking out all kinds of errors to smartctl (which my drives look clean).

 

I've attached the output from smartctl and syslog to this post as well

 

 

Does anyone have any ideas, or what I should check into more?

 

Info:

unRAID 5.0rc12a

preclear_disk.sh v1.13

smartctl shows no issues with any of the 3 drives

syslog has no errors anywhere in it during the preclear process

 

Key System Specs:

Intel Xeon E3-1275

ASRock Z68 EXTREME7

32GB DDR3 1333Mhz

3x WD Red 3TB (WD30EFRX)

syslog_smartctl_may242013.zip

Have you tried running your 32GB preclear box with the 4GB memory limitation option when unRAID boots?  Or are the specs you have for your unRAID box and not your workstation?

The specs posted are for the box I am using to preclear - I have not tried it with the 4GB limit...That's right I do recall now that there were some posts about a write slowdown without using it..Let me test and I guess I'll report back sometime during / after the weekend

 

*edit* - Running preclear with skipping the pre-read for testing, looks like the 4GB limit fixed it, it's running @143MB/s now

I wish I would have remembered that when I was trying to fix this Thanks much BobPhoenix!