[Lustre-discuss] ram disk

[Robert Olson]

Sounds like the SiCortex Fabricache:

http://sicortex.com/5832_newsletter/the_sicortex_fabricache/ 
the_sicortex_fabricache_measure_its_abilities_in_genomes_sec

--bob

On Nov 23, 2007, at 2:45 PM, Antonio Concas wrote:

> There is a particular kind of application, single-client
> and serial process, for which a striped file system using
> RAM disk would be very useful.  Consider reading small
> blocks at random locations on a hard disk.  The latency
> of the HDD could be large, a few milliseconds.  Adding more
> HDD's does not solve the problem, unlike an application based
> on streaming.  Adding more disks and parallelizing the program
> could be a solution but sometimes there is no time
> to parallelize the program.
>
>    A possible solution is RAM disk.  But if we put, for example,
> 64 GB of RAM on a single computer then that computer becomes
> specialized and expensive, whereas the need for a huge
> amount of RAM may be only temporary.  An alternative is to
> use a cluster of nodes, a typical Beowulf cluster.  For example,
> using a striped file system over 16 nodes where each node has 4 GB
> of RAM.  Each node would have a normal amount of RAM and yet
> could provide the aggregate storage of 64 GB when the need arises.
> While we have not yet created this configuration, I suppose
> that Gbit Ethernet could provide 100 microsecond latency and
> Infiniband or Myrinet could provide 10 microsecond latency.
> Much, much less than the seek time of a HDD.
>
>    The idea is so simple that I imagine it has already been done.
> I would be interested in learning from other sites that have
> used this method with the Lustre file system.
>
> best regards,
>
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