Re: MD/RAID time out writing superblock

[Mark Lord]

Chris Webb wrote:
> Chris Webb <chris@xxxxxxxxxxxx> writes:
>
> > Mark Lord <liml@xxxxxx> writes:
> >
> > > Speaking of which..
> > >
> > > Chris:  I wonder if the errors will also vanish in your situation
> > > by disabling the onboard write-caches in the drives ?
> > >
> > > Eg.  hdparm -W0 /dev/sd?
> > Hi Mark. I've got a test machine on its way at the moment, so I'll make sure
> > I check this one out on it too.
>
> Our test machine is still being built, but we had an opportunity to try this on
> a couple of the live machines when their RAID arrays failed over the weekend.
> We still got timeouts, but (predictably!) they're not on flushes any more:
>
>   ata2.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x6
>   ata2.00: cmd 35/00:08:98:c6:00/00:00:4e:00:00/e0 tag 0 dm
...
> all the way through the night.
>
> I also have these in the log, but they are immediately after turning off the
> write caching in all drives, so may be a red herring with data still being
> written out.
>
>   ata2.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x6
>   ata2.00: cmd c8/00:08:00:20:80/00:00:00:00:00/e0 tag 0 dm
...
> On another machine, I saw this with write caching turned off:
>
>   ata2.00: exception Emask 0x0 SAct 0x1 SErr 0x0 action 0x6 frozen
> ata2.00: cmd 61/08:00:28:1f:80/00:00:00:00:00/40 tag 0 ncq 4096 out
...

0x35 is a 48-bit DMA WRITE, 0xc8 is a 28-bit DMA READ,
and 0x61 is an NCQ WRITE.

Looks like some kind of hardware trouble to me.
And as Tejun suggested, it's difficult to guess at
a cause other than the PSU.

Cheers, and good luck.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/