[Beowulf] Any recommendations for a good JBOD?

[Joe Landman]

Tim Cutts wrote:

> on between the two.  We've been looking at iSCSI for our VMware setup in 
> the future.  As people have been saying, performance isn't stellar, an 
> to get it decent you still end up paying a lot of money on networking 
> kit, because ideally in that scenario you still want the storage traffic 

Hmmm... Our sub $10k USD units sport 10GbE/IB interfaces and do more 
than 500 MB/s over iSCSI, sustained.  We've been demonstrating this for 
~1.25 years.  No more expensive than other technologies.  Much less 
expensive than some others.

Yeah, I know, the vast majority of iSCSI users use it over GbE.  Most of 
the units on the market from others have trouble keeping that single GbE 
pipe filled, and they are expensive kit.

> But for HPC?  Nah - can't really see its utility.

It is in use and its use is growing.  Look at iSCSI as glue logic 
between systems.  You can use SAS to connect arrays, then you need an 
expander chip in the backplane for the array (talk about a performance 
killer ...).  You can use FC to connect arrays, with the same types of 
issues (no expander chip, but a massive oversubscription of bandwidth, 
and really expensive networking kit).  Or you can use point to point 
iSCSI, or iSCSI over a switch.  We've done and seen both the point to 
point and networked version.  Works great for its use cases.

For massively oversubscribed SAS/FC networks, the iSCSI systems come in 
less expensive.  For point to point connections (using iSCSI as a wire 
protocol to directly attach RAIDed arrays or JBOD arrays, or mixtures, 
to a server) it works great, and you can do multipathing without 
additional switches ... as well as doing fail-over connections, 
including background replication over a private iSCSI to iSCSI network 
to have HA storage.

It has lots of utility.  Its relatively cheap, and if you get from the 
right vendors, its as fast as some others "fast" and expensive solutions.

Of course, we are biased given what we sell.

> 
> Tim
> 
> 


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Joseph Landman, Ph.D
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