Apparently spurious ZFS CRC errors (was Re: ZFS data error without reasons)

[Alexey Shuvaev]

On Wed, Mar 25, 2009 at 07:38:32PM +0100, Bernd Walter wrote:
> On Wed, Mar 25, 2009 at 06:04:08PM +0000, Mark Powell wrote:
> > On Wed, 25 Mar 2009, Bernd Walter wrote:
> > 
> > >On Wed, Mar 25, 2009 at 03:21:28PM +0100, Alexander Leidinger wrote:
> > >I wouldn't be surprised if the problem is in the drive firmware.
> > >Preread and wc both have the potential to put a lot load to the drives
> > >and can trigger bugs that otherwise wouldn't matter.
> > 
> > I've emailed WD support for more info. Not expecting much though.
> > From reading other threads on these Green Power drives them seem rather 
> > crap. This is my model and firmware:
> > 
> > http://www.datacent.com/datarecovery/hdd/western_digital/WD10EADS-00L5B1
> > 
> > There's some head park problem too, but with 5s ZFS sync I don't think it 
> > applies in this case:
> > 
> > http://www.silentpcreview.com/forums/viewtopic.php?t=51401&postdays=0&postorder=asc&start=120&sid=a1caf68d80ef8fecc5d9e86defde4c19
> > http://kerneltrap.org/mailarchive/linux-kernel/2008/4/9/1386304
> > 
> > >I also have a system running WD drives and ECC RAM which show CRC errors
> > >from time to time, while all other systems have no CRC problem at all.
> > 
> > Interesting. Are those CRC problems with WC on or off?
> 
> WC is on, prefetch is off, but only because it had bad performance with
> MySQL.
> Drives are <WDC WD3200AAKS-00SBA0/12.01B01> Serial ATA II
> I don't know if it is with the drives, but other reasons are less
> likely in my opinion.
> The system is located in a data center and since I only get a few errors
> I decided to live with it and not to debug it further.
> 
Hello!

Me too...

I don't use zfs, just ufs2 + soft updates, but I see sometimes rather
heavy data corruption (most often on / filesystem).
No kernel messages, I can shut down the system successfully just
to find the remnants of filesystems on the next boot.
It doesn't happen often, I think compiling ports in a jail + some
activity in the host increase the probability of a failure.

The drive is:
ATA channel 3:
    Master:  ad6 <WDC WD5000AAKS-00C8A0/12.01C02> SATA revision 2.x

hw.ata.wc=1 (default)

FWIW,
Alexey.