[Lustre-discuss] Client and OST on Same Blade

[Brian J. Murrell]

On Mon, 2008-07-07 at 17:00 -0400, Roger Spellman wrote:
> Is there any problem having a Client and OST on the same blade?

If by "same blade" you mean on the same kernel sharing the same memory
pool, yes, the problems that there were still are.  They are inherent
problems in which the client and OST share the same memory pool and an
effort to relieve memory pressure (by the client) requires memory be
available to the OST.  Of course if the client is experiencing memory
pressure so is the OST and the OST might not get the memory it needs to
help the client get the memory it needs since it's all one pool of
memory.  Indeed it's a deadlock.

I've discussed this with one of the more VM knowledgeable engineers than
I and IIRC his feeling that here really is no fool-proof fix for this.
Perhaps somebody more expert in the VM wants to explain further.

b.


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