[c-nsp] Nexus 5K optimisation for iSCSI traffic

[John Gill]

Matthew,
When you say a large deployment, can you describe the number of FEXes 
and hosts?
Which model of FEX?
What speed are your heads, how many connections?
What speed are your hosts, how many connections?
Mostly reading, writing, random?

You can increase the buffer size available per port on the FEXes, but it 
would be good to know if this kind of configuration would be beneficial 
to you.  It would mean acting more in a shared manner - so any one 
transfer will have access to more buffers, but there could be contention 
of those buffers if every other port is also performing in the same manner.

Regards,
John Gill
cisco


On 8/5/11 7:05 AM, Matthew Melbourne wrote:
> Hi,
>
> We're implementing two pairs of N5Ks (and downstream N2k FEXes) to act
> as separate iSCSI SAN fabrics, with SAN heads attached directly to
> N5Ks and host ports (and downstream integrated blade switches)
> connecting to the FEXes. Does anyone have any real-world experience of
> using N5Ks for a large iSCSI deployment. I have enabled jumbo frames
> through a network-qos policy-map as an obvious first-step, but wonder
> whether anything can be optimised by tuning buffer sizes to
> accommodate the bursty nature of iSCSI (etc)? This switches will only
> be switching iSCSI traffic.
>
> Cheers,
>
> Matt
>