[Lustre-discuss] Anybody actually using Flash (Fusion IO specifically) for meta data?

David Dillow dillowda at ornl.gov
Thu May 19 13:45:39 PDT 2011


On Thu, 2011-05-19 at 12:45 -0700, Carlson, Timothy S wrote:
> > On May 19, 2011, at 10:28, Kevin Van Maren wrote:
> > > Dardo D Kleiner - CONTRACTOR wrote:
> > > As for putting the entire filesystem on flash, sure that would be
> > pretty
> > > nifty, but expensive.  Not being able to do failover, with storage on
> > > internal PCIe cards, is a downside.
> >
> >  [Andreas added this comment]
> > I doubt this will be possible for a long time to come, due to cost,
> > even if
> > the PCI cards have external interfaces (as I've heard some high-end
> > ones do).
> 
> I hate to snip out most of a thread, but I want to focus on the issues of cost and failover.
> 
> As for cost, I really don't think this is an issue. If I am investing
> in a file system that is either approaching a Petabyte or is larger
> than a Petabyte then I don't see that purchasing a 5K-10K flash device
> is really a cost factor. It is not quite in the noise, but it is going
> to be less than 5% of the total purchase price of a the file system.

Uhm, They are talking about building the entire file system out of
flash. Have you priced Petabytes of flash lately? There are small
countries you could buy for less money... ;)

Buying flash for just the MDT would be in the 5% range you mention, but
you only get better cache-cold performance. Better to spend the money on
more memory for your MDS, and avoid downtime, IMO.

-- 
Dave Dillow
National Center for Computational Science
Oak Ridge National Laboratory
(865) 241-6602 office




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