[Lustre-discuss] How smart is Lustre?

[David Noriega]

In my experience, if there is a particular driver for multipathing from the
vendor, go for that. In our setup, we have Oracle/Sun disk arrays and with
the standard linux multipathing daemon, I would get lots of weird I/O
errors. Turns out the disk arrays had picked their preferred path, but
Linux was trying to talk to the LUNs on both paths and would only receive a
response on the preferred one.

There is an rdac driver that can be installed. Simply disable the
multipathing daemon or configure it to ignore the disk arrays and use the
vendor solution. I had no more I/O errors(Which only served to slow down
the boot up process).


On Wed, Dec 19, 2012 at 11:36 AM, Jason Brooks <brookjas at ohsu.edu> wrote:

> Hello,
>
> I am building a 2.3.x filesystem right now, and I am looking at setting up
> some active-active failover abilities to my oss's.  I have been looking at
> Dell's md3xxx arrays, as they have redundant controllers, and allow up to
> four hosts to connect to each controller.
>
> I can see how linux multi-path can be used with redundant disk
> controllers.  I can even (slightly) understand how lustre fails over when
> an oss goes down.
>
>
>    1. Is lustre smart enough to use redundant paths, or failover oss's if
>    an oss is congested?  (it would be cool, no?)
>    2. Does the linux multi-path module slow performance?
>    3. How much does a raid array such as the one listed above act as a
>    bottleneck, say if I have as many volumes available on the raid controllers
>    as there are oss hosts?
>    4. Are there arrays similar to Dell's model that would work?
>
> Thanks!
>
> --jason
>
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