[OmniOS-discuss] iSCSI target hang, no way to restart but server reboot

Narayan Desai narayan.desai at gmail.com
Fri Mar 27 15:13:42 UTC 2015

Having been on the receiving end of similar advice, it is a frustrating
situation to be in, since you have (and will likely continue to have) the
hardware in production, without much option for replacement.

When we had systems like this, we had a lot of success being aggressive in
swapping out disks that were showing signs of going bad, even before
critical failures occurred. Also looking at SMART statistics, and
aggressively replacing those as well. This made the situation manageable.
Basically, having sata drives in sas expanders means the system is brittle,
and you should treat it as such. Look for:
 - errors in iostat -En
 - high service times in iostat -xnz
 - smartctl (this causes harmless sense messages when devices are probed,
but it is easy enough to ignore these)
 - any errors reported out of lsiutil, showing either problems with
cabling/enclosures, or devices
 - decode any sense errors reported by the lsi driver

Aggressively replace devices implicated by these, and hope for the best.
The best may or may not be what you're hoping for, but may be livable; it
was for us.
good luck

On Fri, Mar 27, 2015 at 10:04 AM, Dan McDonald <danmcd at omniti.com> wrote:

> > On Mar 27, 2015, at 11:03 AM, Matej Zerovnik <matej at zunaj.si> wrote:
> >
> > Only rpool is on megaraid, the storage is on LSI Logic SAS2308 HBA,
> which I think is using mpt_sas driver. What change do you plan on putting
> it? Does it concern mpt_sas driver?
> There are some mpt_sas improvements, but no amount of driver improvements
> can fix the failure modes caused by SATA drives in SAS expanders.  You Just
> Can't Fix That.
> >>> I wouldn't like to do a major upgrade, since this is a production
> machine. Too scary:)
> >> You should plan for it, however.  SATA drives on SAS expanders is a
> recipe for disaster, as you're seeing.
> > Is there a better support for SATA drives in newer omnios?
> Not when you're using them in situations that are operationally dangerous.
> Were you a paying customer, we would tell you we don't support SATA drives
> in SAS expanders.
> Sorry,
> Dan
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