RE: Linux Native Multipath, ASM and Instance Failures

  • From: "CRISLER, JON A" <JC1706@xxxxxxx>
  • To: "development@xxxxxxxxxxxxxxxxx" <development@xxxxxxxxxxxxxxxxx>, "oracle-l@xxxxxxxxxxxxx" <oracle-l@xxxxxxxxxxxxx>
  • Date: Fri, 27 Jul 2012 14:29:04 +0000

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@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx] On 
Behalf Of Martin Bach
Sent: Friday, July 27, 2012 4:20 AM
To: oracle-l@xxxxxxxxxxxxx
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
--
//www.freelists.org/webpage/oracle-l


--
//www.freelists.org/webpage/oracle-l

Other related posts:

  1. Home
  2. oracle-l
  3. Archive
  4. 07-2012