[rhelv6-list] Performance issues with RHEL6 (iowait)

[Lamar Owen]

On Wednesday, February 09, 2011 04:47:21 am Matthias Saou wrote:
> it's a Supermicro X8STi motherboard (Xeon i7 920) with two cheap
> SATA disks (WD10EADS-00P8B0) using software RAID-1.

The WD EADS drives aren't usable in RAID configurations, by design, at least apparently with recent kernels.  Google the string 'WDTLER' to find out more information.  This issue is not isolated to Linux, either, with these low-end WD drives.  WD has 'RE' drives that are set up in such a way to work well with RAID.

I had one of the 1.5TB EADS drives in RAID 1 with a Seagate 1.5TB; the WD unit was constantly creating iowaits.

I didn't try with the EL5 kernel; it's interesting that it works there and not with EL6.  You could try the Fedora releases from FC6 up through F14 and see which kernel rev broke it; that would help troubleshoot this annoying issue.

I would, but I no longer have that EADS drive available for testing.