[Lustre-discuss] Could "Client & MGS" or "Client & OSS" running at one node together?

[Peter Grandi]

> Since there is no more node in our project when using Lustre,
> I want to confirm that:

> 1) Could the "Client" and "MGS" run at one node together? or
> could "Client" and "OSS" run at one node together? 2) Suppose
> I had deployed them at one node, what potential shortcomings
> or harm are there?

Running MGS and MDS on the same nodes is customary, see:
   http://wiki.lustre.org/manual/LustreManual20_HTML/LustreOperations.html#50438194_24122

Running the MGS, MDS and OSS service on the same node is
possible and fairly common in very small setups, usually those
in which there is only 1-2 nodes.

It is possible to use the client code on all types of Lustre
servers, but at least in the case of using the client code on an
OSS there is the non-negligible possibility of a resource
deadlock, if the client uses the OSS on the same node, as the
client and OSS codes compete for memory, so in the past this has
been discouraged.

This is documented here:
  http://wiki.lustre.org/manual/LustreManual20_HTML/LustreOperations.html#50438194_84876
   «Caution - Do not do this when the client and OSS are on the
    same node, as memory pressure between the client and OSS can
    lead to deadlocks.»