[Beowulf] clustering using xen virtualized machines

Gavin Burris bug at sas.upenn.edu
Wed Jan 27 10:18:49 EST 2010


The cost for virtualization is in buying really big hardware, oodles of
memory and many many cores, that are capable of running multiple VMs,
and having that hardware configured for redundancy, high availability
and failover.

With an HPC cluster, you are typically buying hardware that is as
stripped down and cheap as you can get it.  You focus your HPC budget on
the sweet-spot processor, the amount of memory, maybe GPUs, maybe
interconnect, so you can deploy as many compute server nodes as you can
afford.

I don't buy the argument that the winning case is packaging up a VM with
all your software.  If you really are unable to build the required
software stack for a given cluster and its OS, I think using something
like xCAT to provision stateless compute servers per job is a better
option than virtualization.

And if you are packaging VMs to blast out to the cloud, I think you will
be paying through the nose.  This is not a viable option unless there is
a major pricing shift.

Cheers.


On 01/27/2010 07:08 AM, Jonathan Aquilina wrote:
> gavin you mentioned costs, those are only incurred with xen if you need
> the extra features such as server migration and other features. also if
> you dont need those extra features couldnt you just live with the free
> version of xen.
> 
> On Wed, Jan 27, 2010 at 11:42 AM, Geoff Galitz <geoff at galitz.org
> <mailto:geoff at galitz.org>> wrote:
> 
> 
> 
>     I've had the good fortune to be in the HPC and also HA business for
>     a few
>     years (10 years for HPC but only about 4 for HA).  Given the current
>     approach for virtualization I don't see that Xen or other virtualization
>     technologies are good for HPC environments if the performance is a
>     paramount
>     concern.
> 
>     Virtualization in an HPC/HA world is mostly beneficial for
>     portability and
>     fail-over.  But the added layer for a hypervisor will be significant
>     if your
>     jobs run for an extended period of time.  I've seen jobs that run for
>     months...  a 7% performance penalty (fairly typical in my
>     experience) over
>     the course of a month is significant.
> 
> 
> 
>     ---------------------------------
>     Geoff Galitz
>     Blankenheim NRW, Germany
>     http://www.galitz.org/
>     http://german-way.com/blog/
> 
> 
> 
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> 
> 
> 
> -- 
> Jonathan Aquilina
> 
> 
> 
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