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SubjectRe: Have the velociraptors in a test system now, checkout the errors.
Justin Piszcz wrote:
> Point of thread: Two problems, mentioned in detail below, NCQ in Linux
> when used in a RAID configuration and two, something with how Linux
> interacts with the drives causes lots of problems as when I run the WD
> tools on the disks, they do not show any errors.
>
> If anyone has/would like me to run any debugging/patches/etc on this
> system feel free to suggest/send me things to try out. After I put
> the VR's in a test system, I left NCQ enabled and I made a 10 disk
> raid5 to see how fast I could get it to fail, I ran bonnie++ shown
> below as a disk benchmark/stress test:
>
> For the next test I will repeat this one but with NCQ disabled, having
> NCQ enabled makes it fail very easily. Then I want to re-run the test
> with RAID6.
>
> bonnie++ -d /r1/test -s 1000G -m p63 -n 16:100000:16:64
>
> $ df -h
> /dev/md3 2.5T 5.5M 2.5T 1% /r1
>
> And the results? Two disk "failures" according to md/Linux within a
> few hours as shown below:
>
> Note, the NCQ-related errors are what I talk about all of the time, if
> you use
> NCQ and Linux in a RAID environment with WD drives, well-- good luck.
>
> Two-disks failed out of the RAID5 and I currentlty cannot even 'see'
> one of the drives with smartctl, will reboot the host and check sde
> again.
>
> After a reboot, it comes up and has no errors, really makes one wonder
> where/what the bugs is/are, there are two I can see:
> 1. NCQ issue on at least WD drives in Linux in SW md/RAID
> 2. Velociraptor/other disks reporting all kinds of sector errors etc,
> but when you use the WD 11.x disk tools program and run all of their
> tests it says the disks have no problems whatsoever! The smart
> statistics do confirm this. Currently, TLER is on for all disks, for
> the duration of these tests.

Just a few comments on this, I have several RAID arrays built on Seagate
using NCQ, and yet to have a problem. I have NCQ on with my WD drives,
non-RAID, and haven't had an issue with them either. The WDs run a lot
cooler than the SG, but they are probably getting less use, as well. If
the WD are still on sale after the holiday I may grab a few more and run
RAID, by then I will have some small sense of trusting them.

--
Bill Davidsen <davidsen@tmr.com>
"Woe unto the statesman who makes war without a reason that will still
be valid when the war is over..." Otto von Bismark




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