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Re: Have the velociraptors in a test system now, checkout the errors.

To: Redeeman <redeeman@xxxxxxxxxxx>
Subject: Re: Have the velociraptors in a test system now, checkout the errors.
From: Bill Davidsen <davidsen@xxxxxxx>
Date: Wed, 17 Dec 2008 15:43:11 -0500
Cc: Justin Piszcz <jpiszcz@xxxxxxxxxxxxxxx>, linux-kernel@xxxxxxxxxxxxxxx, linux-raid@xxxxxxxxxxxxxxx, xfs@xxxxxxxxxxx, smartmontools-support@xxxxxxxxxxxxxxxxxxxxx
In-reply-to: <1229225303.16555.149.camel@localhost>
Organization: TMR Associates Inc, Schenectady NY
References: <alpine.DEB.1.10.0812060426280.3494@xxxxxxxxxxxxxxxx> <49405A94.8080601@xxxxxxx> <1229225303.16555.149.camel@localhost>
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Redeeman wrote:
> On Wed, 2008-12-10 at 19:11 -0500, Bill Davidsen wrote:
>> 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.
> Velociraptors, or which WD?

Calls itself "WDC WD10EACS-00D" in /sys if that helps. I could dig out 
the packing slip if it matters. Runs nicely so far, and if the SMART 
temperature probe is correct, very cool:

/dev/sda: ST3750640AS: 43 C
/dev/sdb: WDC WD10EACS-00D6B1: 31 C
/dev/sdc: ST3750640AS: 44 C
/dev/sdd: ST3750640AS: 46 C

I don't totally trust the temps, there is a LOT of 18C air going into 
that box, because it has a lot coming out the back and side.

Bill Davidsen <davidsen@xxxxxxx>
  "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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