[Beowulf] Suggestions to what DFS to use

Scott Atchley e.scott.atchley at gmail.com
Wed Feb 15 05:43:51 PST 2017

Hi Chris,

Check with me in about a year.

After using Lustre for over 10 years to initially serve ~10 PB of disk and
now serve 30+ PB with very nice DDN gear, later this year we will be
installing 320 PB (250 PB useable) of GPFS (via IBM ESS storage units) to
support Summit, our next gen HPC system from IBM with Power9 CPUs and
NVIDIA Volta GPUs. Our current Lustre system is capable of 1 TB/s for large
sequential writes, but random write performance is much lower (~400 GB/s or
40% of sequential). The target performance for GPFS will be 2.5 TB/s
sequential writes and 2.2 TB/s random (~90% of sequential). The initial
targets are slightly lower, but we are supposed to achieve these rates by

We are very familiar with Lustre, the good and the bad, and ORNL is the
largest contributor to the Lustre codebase outside of Intel. We have
encountered many bugs at our scale that few other sites can match and we
have tested patches for Intel before their release to see how they perform
at scale. We have been testing GPFS for the last three years in preparation
for the change and IBM has been a very good partner to understand our
performance and scale issues. Improvements that IBM are adding to support
the CORAL systems will also benefit the larger community.

People are attracted to the "free" aspect of Lustre (in addition to the
open source), but it is not truly free. For both of our large Lustre
systems, we bought block storage from DDN and we added Lustre on top. We
have support contracts with DDN for the hardware and Intel for Lustre as
well as a large team within our operations to manage Lustre and a full-time
Lustre developer. The initial price is lower, but at this scale running
without support contracts and an experienced operations team is untenable.
IBM is proud of GPFS and their ESS hardware (i.e. licenses and hardware are
expensive) and they also require support contracts, but the requirements
for operations staff is lower. It is probably more expensive than any other
combination of hardware/licenses/support, but we have one vendor to blame,
which our management sees as a value.

As I said, check back in a year or two to see how this experiment works out.


On Wed, Feb 15, 2017 at 1:53 AM, Christopher Samuel <samuel at unimelb.edu.au>

> Hi John,
> On 15/02/17 17:33, John Hanks wrote:
> > So "clusters" is a strong word, we have a collection of ~22,000 cores of
> > assorted systems, basically if someone leaves a laptop laying around
> > unprotected we might try to run a job on it. And being bioinformatic-y,
> > our problem with this and all storage is metadata related. The original
> > procurement did not include dedicated NSD servers (or extra GPFS server
> > licenses) so we run solely off the SFA12K's.
> Ah right, so these are the embedded GPFS systems from DDN. Interesting
> as our SFA10K's hit EOL in 2019 and so (if our funding continues beyond
> 2018) we'll need to replace them.
> > Could we improve with dedicated NSD frontends and GPFS clients? Yes,
> > most certainly. But again, we can stand up a PB or more of brand new
> > SuperMicro storage fronted by BeeGFS  that performs as well or better
> > for around the same cost, if not less.
> Very nice - and for what you're doing it sounds like just what you need.
> > I don't have enough of an
> > emotional investment in GPFS or DDN to convince myself that suggesting
> > further tuning that requires money and time is worthwhile for our
> > environment. It more or less serves the purpose it was bought for, we
> > learn from the experience and move on down the road.
> I guess I'm getting my head around how other sites GPFS performs given I
> have a current sample size of 1 and that was spec'd out by IBM as part
> of a large overarching contract. :-)
> I guess I assuming that because that was what we had it was how most
> sites did it, apologies for that!
> All the best,
> Chris
> --
>  Christopher Samuel        Senior Systems Administrator
>  VLSCI - Victorian Life Sciences Computation Initiative
>  Email: samuel at unimelb.edu.au Phone: +61 (0)3 903 55545
>  http://www.vlsci.org.au/      http://twitter.com/vlsci
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