[OmniOS-discuss] slow drive response times

[Kevin Swab]

Hello Everyone,

	We've been running OmniOS on a number of SuperMicro 36bay chassis, with
Supermicro motherboards, LSI SAS controllers (9211-8i & 9207-8i) and
various SAS HDD's.  These systems are serving block storage via Comstar
and Qlogic FC HBA's, and have been running well for several years.

	The problem we've got is that as the drives age, some of them start to
perform slowly (intermittently) without failing - no zpool or iostat
errors, and nothing logged in /var/adm/messages.  The slow performance
can be seen as high average service times in iostat or sar.

	When these service times get above 500ms, they start to cause IO
timeouts on the downstream storage consumers, which is bad...

	I'm wondering - is there a way to tune OmniOS' behavior so that it
doesn't try so hard to complete IOs to these slow disks, and instead
just gives up and fails them?

	I found an old post from 2011 which states that some tunables exist,
but are ignored by the mpt_sas driver:

http://everycity.co.uk/alasdair/2011/05/adjusting-drive-timeouts-with-mdb-on-solaris-or-openindiana/

Does anyone know the current status of these tunables, or have any other
suggestions that might help?

Thanks,
Kevin


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Kevin Swab                          UNIX Systems Administrator
ACNS                                Colorado State University
Phone: (970)491-6572                Email: Kevin.Swab at ColoState.EDU
GPG Fingerprint: 7026 3F66 A970 67BD 6F17  8EB8 8A7D 142F 2392 791C