Re: "Out of Memory: Killed process" errors on server running Oracle

[Eric Sisler <esisler westminster lib co us>]

Hi Tom,

> Well, do you run RHEL3 on servers with 16GB?  It's not fair to compare a
> system with 16GB to a system with 4GB.

No - the largest I have running RHEL 3 is 6Gb.

> The kernel uses low memory to track allocations of all memory thus system with
> 16GB of memory will use significantly more low memory than a system with 4GB,
> perhaps as much as 4 times.  This extra pressure happens from the moment
> you turn the system on before you do anything at all because the kernel
> structures have to be sized for the potential of tracking allocations in
> four times as much memory.

Thanks for this excellent explanation.  I have a dim recollection of
this, but apparently not enough to trigger further though
unassisted.  ;-)

> > Any idea which would be better - switching to 64-bit or running the
> > hugemem kernel on 32-bit?

> The hugemem kernel has some overhead, I would go with 64-bit personally,
> but it's up to you.  Hugemem is certainly easier because it's just a
> quick kernel change.

Unfortunately I can't take the server with 16Gb out of production at the
moment.  I have a slightly older server with 8Gb of RAM that has
experienced similar problems that I can take out of service for testing.
I'll check the values of 'LowTotal' & 'LowFree' with the 32-bit kernel,
the 32-bit hugemem kernel & the 64-bit kernel, plus stress test the box
by firing up multiple VMs.  I'll report my findings.

Thanks!

-Eric

-- 
Eric Sisler <esisler westminster lib co us>
Library Network Specialist
Westminster Public Library
Westminster, CO USA

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