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

[Eric Sisler <esisler westminster lib co us>]

Hi Tom,

> Google is certainly your friend here, but you can install the kernel-doc
> package and the find the information
> in /usr/share/doc/kernel-doc-2.6.9/Documentation/sysctl 

Will do.

> BTW, it's seems likely to me that your configuration is suspect,
> especially if you are using the default VMware server configuration.  By
> default VMware Server locks most of the memory for the virtual machines
> so that the bulk of the VM will stay in memory.  It does this for
> performance since locked memory cannot be swapped.
> 
> So let's take a look at your config, you have an 8GB machine and 10.5GB
> of VM's to start.  Now you state that this overloads the physical system
> by 2.5GB, but actually, you seem to forget that the OS needs some and
> VMware application needs some memory too, so it's far more likely that
> your overloading the system by 3GB or more.

Well yes, I was talking about the potential for overload from just the
VM standpoint, not VMs + the OS.  My test server also isn't anything I
would configure for the real-world.  I intentionally increased the RAM
on the VMs to try and trigger an oom-kill or system halt.  Normally this
particular server would have VMs configured for ~5Gb.

> You can change the memory locking behavior of VMware Server slightly by
> setting the memory host parameters from "Allow some virtual memory to be
> swapped" to "Allow most virtual memory to be swapped".  Oversubscribing
> memory and trying to combine that with locking the memory in place is a
> very dangerous combo and may never be as stable as you would like.

On a production server I wouldn't have any reason to set VMware to
"allow most...".  Assuming a production server with a reasonable number
of VMs for the available RAM, are there any dangers to using the
lower_zone_protection option you can think of or have experienced?

> > Gene: If you haven't tried adjusting lower_zone_protection, I would
> > recommend doing so.

> I think Gene's problem was on RHEL3.  I don't think RHEL3 even has this
> tunable, and it's likely that his problem is actually different,
> although perhaps similar.  I had meant to suggest that we move your
> thread to the RHEL4 list earlier.

Looking back, I see it was - sorry.  I didn't check my RHEL 3 box to see
if it has this option.

-Eric

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

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