Re: [Xen-users] Shared Storage

[John Madden <jmadden@xxxxxxxxxxx>]

On 04/26/2011 04:31 PM, Javier Guerra Giraldez wrote:
> On Tue, Apr 26, 2011 at 3:21 PM, Jonathan Tripathy<jonnyt@xxxxxxxxxxx>  wrote:
> > On 26/04/2011 18:53, Javier Guerra Giraldez wrote:
> > > more like .96gbit storage and .04gbit protocol.... or .993/.007 on jumbo
> > > frames
> > Are you using TCP and/or iSCSI offload in your NIC? Those seem like pretty
> > good numbers.
> that's the protocol overhead; what John guessed would be .8/.2   He's
> right in that no amount of offloading or CPU power would improve on
> that, but his numbers are way off.
Some good summary numbers are near the bottom here (PDF):

http://www.google.com/url?sa=t&source=web&cd=1&ved=0CCIQFjAA&url=http%3A%2F%2Fwww.rainiersolutions.com%2FRainierLibrary%2FiSCSI%2520SAN%2520Performance.pdf&rct=j&q=iscsi%20throughput%20gigabit&ei=NC63TaGhI8n50gGJl4kF&usg=AFQjCNGqiaj31yc3XYue97OL9KpPyo_zDg&cad=rja

With a MTU of 1500, they're claiming 94.93% payload.  On GbE, I don't 
believe I've seen more than ~100MB/s on any protocol, hence my estimate 
of 20% overhead.
John




--
John Madden
Sr UNIX Systems Engineer / Office of Technology
Ivy Tech Community College of Indiana
jmadden@xxxxxxxxxxx

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