constant zfs data corruption

Jeremy Chadwick koitsu at FreeBSD.org
Mon Oct 20 10:15:17 PDT 2008


On Mon, Oct 20, 2008 at 03:07:30PM -0200, JoaoBR wrote:
> On Monday 20 October 2008 11:22:08 you wrote:
> > On Mon, Oct 20, 2008 at 08:37:40AM -0200, JoaoBR wrote:
> > > On Friday 17 October 2008 15:39:59 Chuck Swiger wrote:
> > > > On Oct 17, 2008, at 11:30 AM, JoaoBR wrote:
> > > > > constantly I find data corruption on ZFS volums, ever from rrdtool,
> > > > > this
> > > > > corrupt data happens on SATA disks, never seem on SCSI
> > > >
> > > > Presumably your SATA drives are correctly being reported by ZFS as
> > > > corrupting data, and you should do something like replace cables, the
> > > > drives themselves, perhaps try downgrading to SATA-150 rather than
> > > > -300 if you are using the later.  Also consider running a drive
> > > > diagnostic utility from the mfgr (or smartmontools) and doing an
> > > > extended self-test or destructive write surface check.
> > >
> > > well, hardware seems to be ok and not older than 6 month, also happens
> > > not only on one machine ... smartctl do not report any hw failures on
> > > disk
> > >
> > > regarding jumpering the drives to 150 you suspect a driver problem?
> >
> > It's not because of a driver problem.  There are known SATA chipsets
> > which do not properly work with SATA300 (particularly VIA and SiS
> > chipsets); they claim to support it, but data is occasionally corrupted.
> > Capping the drive to SATA150 fixes this problem.
> >
> > http://en.wikipedia.org/wiki/Serial_ATA#SATA_1.5_Gbit.2Fs_and_SATA_3_Gbit.2
> >Fs
> >
> > There are also known problems with Silicon Image chipsets (on Linux,
> > Windows, and FreeBSD).
> >
> > Because you didn't provide your smartctl output, I can't really tell if
> > the drives are in "good shape" or not.  :-)
> >
> 
> ok then here it comes
> {snip}

Yup, looks fine.  All attributes are quite decent, except Temperature,
which is high (46C, highest seen is 52C -- blazing hot).  However, I
refuse to believe that a high drive temperature would manifest itself as
data corruption on only certain kinds of files.  :-)  So I think your
drive is in OK shape.

> > Also, do you not think it's a little odd that the only data corruption
> > occurring for you are related to RRDtool?
> 
> this yes I think is suspitious

Chuck's probably spot-on with regards to explaining why this is.
Something to keep in mind is that RRDtool has a history of bugs, so I
wouldn't be surprised if the issue turned out to be there.  It's really
too bad we have no decent, actively-maintained alternatives to RRDtool.

-- 
| Jeremy Chadwick                                jdc at parodius.com |
| Parodius Networking                       http://www.parodius.com/ |
| UNIX Systems Administrator                  Mountain View, CA, USA |
| Making life hard for others since 1977.              PGP: 4BD6C0CB |



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