[Lustre-discuss] Rule of thumb for setting up lustre resources...

[Mark True]

*Size:*3.2 k

Hey Brian,

Thanks so much for the prompt response, I do have a couple of questions for
clarification:

Does the hardware makeup of the OSS affect the speed of the OSTs?   If so,
what is likely to be the bottleneck in an OSS.

Say we have an OSS with 3 OSTs attatched, is that different than having
three OSSs with 1 OST apiece?

Also, does the OSS have as much of a performance impact as the speed of the
OST.  What is the recommended max number of OSTs per OSS?

If I am able to determine the max capabilities of an OST/OSS is it safe to
assume that the increase in performance scales linearly as I increase the
number of OSS/OSTs?

Thanks,
--Mark T.


On Mon, Jun 16, 2008 at 10:03 AM, Brian J. Murrell <Brian.Murrell at sun.com>
wrote:

> On Sat, 2008-06-14 at 14:22 -0400, Mark True wrote:
> >
> > Hello!
>
> Hi.
>
> > A> If increasing the number of OSTs increases throughput, is there a
> > relationship that can be used to determine how many OSTs we're likely
> > to need at the outset to establish a baseline minimum throughput.
>
> Of course.
>
> > For examples, if I want to get 3GB sustained throughput how many OSTs
> > will facilitate this.
>
> That is _completely_ dependent on your hardware configuration.  If you
> are adding an "identical" (to an existing) OSTs you can simply use the
> speed of the existing OST to determine how much more the new OST will
> add.  But be very careful of ceilings.  You can of course only add so
> many OSTs before you start to hit other resource limitations such as bus
> bandwidth in the OSS and network bandwidth of the OSS's interconnect,
> etc.  In short, you need to understand the performance capability of all
> of your components to come up with an overall design that meets your
> performance goals and scales to future goals.
>
> > B> Does the MGS and MDS have to be separate for best performance, or
> > can they be consolidated into one server without causing too much
> > hardship
>
> I'd tend to say that most people put them into the same server.  For
> anything but "toy" installations however, we strongly suggest you put
> the MGS and MDT on separate devices.
>
> > C>  Right now I am looking at a model where I am connecting all the
> > OSTs, and the MDS/MGS together using infiniband,
>
> Just to keep the nomenclature straight, an OST is a device (i.e. a disk)
> in/attached to an OSS.  An OSS is the server that serves OSTs.
>
> > and connecting the storage via fibrechannel.   Is this the ideal
> > solution or am I going in the wrong direction.
>
> That sounds suitable.
>
> b.
>
>
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