[Lustre-discuss] multipathd or sun rdac driver?

David Noriega tsk133 at my.utsa.edu
Wed Jul 20 14:41:52 PDT 2011

They are 2540 and I'm running EL5(centos).

Well the thought came around since I had to rebuild a node after a
hardware problem. So I went ahead and gave it a shot. I think I posted
about this problem before somewhere in the mailing list about getting
stray I/O errors which were for /dev/sdX devices that were the other
path to the same device(Well thats the idea we came to). Well after
installing the Sun RDAC module and disabling multipathd, I can happily
say those messages are gone, so I suppose Sun's module is able to talk
to the disk array in a better manner then multipathd. Though I haven't
failed back the lustre ost's to this particular node just yet(will
wait till the weekend). I'll post again if anything goes wrong, but I
think going with this RDAC module might be better.

ps: One thing that has nagged me since Lustre was installed and setup
by a vendor, was the disk arrays were never setup with initiators or
hosts in the configuration(Using CAM). We have another similar disk
array(6140) we setup for another filesystem and I know
initiators/hosts were setup on the array. I can't say that this has
caused any problems, but its something in the back of my mind.


On Wed, Jul 20, 2011 at 4:15 PM, Kevin Van Maren
<kevin.van.maren at oracle.com> wrote:
> David Noriega wrote:
>> We already use multipathd in our install already, but this was
>> something I wondered about. We use Sun disk arrays and they mention
>> the use of their RDAC driver to multipathing on Linux. Since its from
>> the vendor, one would think it be better. What does the collective
>> think?
>> Sun StorageTek RDAC Multipath Failover Driver for Linux
>> http://download.oracle.com/docs/cd/E19373-01/820-4738-13/chapsing.html
>> David
> I assume you are using the ST25xx or ST6xxx storage with Lustre?  Exactly
> which arrays?
> I've been happy with RDAC, but I don't think Oracle has released RHEL6
> support yet
> (but Oracle also does not support Lustre servers on RHEL6 yet).
> If your multupath config is working (ie, you've tested it by
> unplugging/replugging cables
> under load and were happy with the behavior), I'm not going to tell you to
> change.
> Kevin

Personally, I liked the university. They gave us money and facilities,
we didn't have to produce anything! You've never been out of college!
You don't know what it's like out there! I've worked in the private
sector. They expect results. -Ray Ghostbusters

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