RE: Linux Native Multipath, ASM and Instance Failures
Date: Fri, 27 Jul 2012 14:29:04 +0000
Message-ID: <9F15274DDC89C24387BE933E68BE3FD33560F4_at_MISOUT7MSGUSR9D.ITServices.sbc.com>
When I said earlier about multipath bugs, I really meant RH4 and anything older than RH 5.8, especially if you have active -passive configs with round robin and SAN dual controllers. We actually have more problems with NetApp than 3par in this area. Are you using thin-provisioning with 3par ? That's a nice feature and really works, but be careful about tuning the 3par arrays and don't overcommit your I/O rates or number of LUN's. There may still be a limit on the 8192 LUN count, which includes Snaps as well. That said, 3par works pretty darn good- a lot of people didn't believe in the whole thin-provisioning concept would even work (i.e. smoke and mirrors) when we started with it 6 years ago.
-----Original Message-----
From: oracle-l-bounce_at_freelists.org [mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Martin Bach
Sent: Friday, July 27, 2012 4:20 AM
To: oracle-l_at_freelists.org
Subject: Re: Linux Native Multipath, ASM and Instance Failures
Jon,
On 26/07/2012 23:08, CRISLER, JON A wrote:
> you want to check your multipath.conf to make sure it has all the
> right options
that's probably the most important point: check your vendor documentation to ensure that the devices {} are set according to what you need. There are subtle differences in the way that I/Os are distributed, what the library does when it can't write to a device, and which method should be used for path checking. The differences exist even with different product lines of the same vendor: VNX and Symmetrix for example have different entries in the devices {} section! I'm sure the same applies to any other storage product.
There are metalink notes on how to set up multipath.conf in RHEL 5 but although broadly speaking they are correct, they are not necessarily optimal for your configuration.
What's of importance when troubleshooting this kind of problem are kernel (uname -a), and the dm-multipath RPM version. There were known issues in 5.5 but they have alledgedly been fixed in 5.6 and later.
Hope this helps,
Martin
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