AOC-USAS2-L8i zfs panics and SCSI errors in messages

[Rich]

Observation - the LSI SAS expanders, in my experience, sometimes
misbehave when there are drives which respond slower than some timeout
to commands (as far as I've seen it's only SATA drives it does this
for, but I don't have many SAS drives for comparison), leading to all
further commands to that drive for a bit not working, and then what
happens depending on the OS varies dramatically.

If you could try without an expander (e.g. with 1->4 SAS->SATA fanout
cables), you may be surprised (and/or annoyed) to find your life gets
better.

- Rich

On Mon, Nov 7, 2011 at 3:48 AM, Karli Sjöberg <Karli.Sjoberg at slu.se> wrote:
> As a test, I have copied in about 1.5TB and scrubbed several times without any panic. It stayed solid until periodic weekly:( Same panic as with daily.
>
> /Karli Sjöberg
>
> 26 okt 2011 kl. 12.16 skrev Jeremy Chadwick:
>
> On Wed, Oct 26, 2011 at 11:36:44AM +0200, Karli Sj?berg wrote:
> Hi all,
>
> I tracked down what causes the panics!
>
> I got a tip from aragon and phoenix at the forum about
> /etc/periodic/security/100.chksetuid
>
> And to put:
> daily_status_security_chksetuid_enable="NO"
> into /etc/periodic.conf
>
> This is not truly the cause of the panic, it simply exacerbates it.
>
> Many of the periodic scripts will do things like iterate over all files
> on the filesystem looking for specific attributes, etc..  This tends to
> stress filesystems heavily.  This isn't the only one.  :-)
>
> I can now run periodic daily without any panics. I?m still wondering
> about the cause of this, the explanation from the forum was that that
> phase is too demanding for multi TB systems. But I have several multi
> TB servers with FreeBSD and ZFS, and none of them has ever behaved
> this way. Besides, the panic is instantaneous, not degenerative. I
> imagine that a run like that would start out OK and then just get
> worse and worse, getting gradually slower and slower until it just
> wouldn?t cope any more and hang. This feels more like hitting a wall.
> As if it found something that is couldn?t deal with and has no choice
> but to panic immediately.
>
> It may be possible that you have some underlying filesystem corruption
> that triggers this situation.  Have you actually tried doing a "zpool
> scrub" of your pools and seeing if any errors happen or if the panic
> occurs there?
>
> I'm inclined to think what you're experiencing is probably a bug or
> "quirk" in the storage controller driver you're using.  There are other
> drivers that have had fixes applied to them "to make them work decently
> with ZFS", meaning the kind of stressful I/O ZFS puts on them results in
> the controller driver behaving oddly or freaking out, case in point.  It
> could also be a controller firmware bug/quirk/design issue.  Seriously.
>
> I believe the AOC-USAS2-L8i controller has been discussed on
> freebsd-stable, re: mps(4) driver problems or equivalent, but I'm not
> going to CC that list given that there would be 3 cross-posted lists
> involved and that is liable to upset some folks.  You should search the
> mailing lists for discussion of Supermicro controllers that work
> reliably with FreeBSD.
>
> It would be worthwhile to discuss this condition on -stable, mainly with
> something like "Anyone else using the AOC-USAS2-L8i reliably with ZFS?"
> You get the idea.
>
> --
> | Jeremy Chadwick                                jdc at parodius.com<http://parodius.com> |
> | Parodius Networking                       http://www.parodius.com/ |
> | UNIX Systems Administrator                   Mountain View, CA, US |
> | Making life hard for others since 1977.               PGP 4BD6C0CB |
>
>
>
>
> Med Vänliga Hälsningar
> -------------------------------------------------------------------------------
> Karli Sjöberg
> Swedish University of Agricultural Sciences
> Box 7079 (Visiting Address Kronåsvägen 8)
> S-750 07 Uppsala, Sweden
> Phone:  +46-(0)18-67 15 66
> karli.sjoberg at slu.se<mailto:karli.sjoberg at adm.slu.se>
>
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