I've been having performance problems with my unRAID server and after running SMART tests, I've discovered that it is caused by pending sectors. It's a long story, but if you're interested here's the thread:

 

http://lime-technology.com/forum/index.php?topic=25499.0

 

I had the performance problem twice. To really complicate matters, the second episode revealed that 2 of my drives had pending sectors. After the second time, I immediately purchased a new 2TB hard drive from Newegg so I could use it as a backup or replacement, while I dealt with the vendor or manufacturer to RMA the bad drive. I purchased a Western Digital WD20EURS 2 TB drive, which arrived in a few days (I paid for the accelerated delivery). I installed the new drive, but had problems preclearing it. The performance of the preclear would start out at around 60 MB/sec and by the time it got to around 10% of the zeroing step (step 2 of 10) it would be under 5 MB/sec. Even with the help of forum members (sharing my syslog and SMART status reports), I couldn't figure out why the preclear was so slow. I had a couple of factors that were unnecessary annoyances or distractions, like a bad keyboard and the inability to run memtest from a couple of different USB flash drives, which I eventually solved.

 

Eventually a replacement for one of my RMA'd drives arrived. It was a 3TB Western Digital WD30EZRS, which was weird because the drive it was replacing was only 2TB. Anyhow, I installed it and ran the preclear. The preclear performance for the WD30EZRS was ok. The preread started well over 100 MB/sec and stayed up there until the postread step where it slowed down to about 45 MB/sec. Total time for preclearing the 3TB drives was about 33 hours and 20 minutes. I'm assuming that's a normal or average time period. So I couldn't figure out why a 2TB drive connected to the same SATA ports and power supply was taking so much longer. I never did finish preclearing the WD20EURS because with the speed it was going it would take well over a week to complete, if it even finished. So I decided there must be something wrong with the WD20EURS (even though nothing obvious appeared in the SMART status report) and went ahead and applied for an RMA.

 

The replacement for the WD20EURS arrived yesterday. It was another WD20EURS. I started the preclear yesterday afternoon. The preclear started out at over 90 MB/sec, which doesn't seem too bad, but wasn't as fast as the WD30EURS. However, by the time the preclear was at step 2 of 10 (zeroing), it had slowed down to under 6MB/sec. Every refresh of the screen was showing a slower rate.

 

I shut down my server, disconnected the drive, reconnected it to a different port, restarted the preclear and the performance is still pretty slow.

 

Does anyone else have any experience with preclearing a WD20EURS drive, are they normally this slow?

 

Have I just run into a rather long series of bad luck with drives and this is another that I should send back?

 

I've attached a copy of my syslog and the SMART status report for this drive. Any advice is greatly appreciated.

syslog-2013-03-05.txt

SMART_status_3-5-13.txt

There are no apparent issues at all, in either the SMART report or the syslog (but you probably expected that!).

 

One tip, I noticed you connected the WDEURS to the SiI3132 card, instead of one of the onboard SATA ports.  The SiI3132 card is nice, I use it myself, but being older technology, it only supports UDMA/100, meaning it will cap the top speed of your faster and newer drives.  I would attach faster drives to onboard ports, and only the slowest ones to the SiI3132.  I suspect from the speeds you reported that you also connected the 3TB drive to the same port, when you Precleared it.

I'm not sure that the UDMA/100 vs 133 actually effects the throughput. They both support SATA 2 300MBps. PCIex1 will limit the each drive to 250MBps. The card should have BIOS 7.7.03 (non-RAID). See here: http://www.siliconimage.com/support/.

There are no apparent issues at all, in either the SMART report or the syslog (but you probably expected that!).

 

One tip, I noticed you connected the WDEURS to the SiI3132 card, instead of one of the onboard SATA ports.  The SiI3132 card is nice, I use it myself, but being older technology, it only supports UDMA/100, meaning it will cap the top speed of your faster and newer drives.  I would attach faster drives to onboard ports, and only the slowest ones to the SiI3132.  I suspect from the speeds you reported that you also connected the 3TB drive to the same port, when you Precleared it.

 

All of the ports I've been using are onboard. The first 6 SATA ports are controlled by a 3Gb/s Intel ICH8R, 2 are controlled by a 3Gb/s JMicron JMB363, and 2 are controlled by a 3Gb/s Silicon Image 3132. One of those 10 ports is an eSATA port.

Which MB?

Running preclear on 2 3T drives with 1 on the AMD chipset and the other on a JMB363 controller I saw about 3 hours longer preclear on the JMB. I wouldn't be too concerned about the SiL3132 being much different than that.

 

Connect to the first 6 ports if you wanted the most conclusive results.

Which MB?

 

It's an Abit AB9 Pro