best practices for iSCSI and 6224/5424 ?

Whats the iSCSI environment ( Dell, EMC etc )?; and is it shared with general data traffic or is it a dedicated IP SAN ( i.e. a LAN carrying only iSCSI traffic )?

Proposed design is a NetApp FAS3020, connected by 2x1Gig LAG to one 6224; and 2x1gig LAG to a second 6224.  Switches are dedicated to SAN traffic only.  The two 6224s trunked together by 2x1gig LAG, running RSTP (no stacking). The 6224s are the switching "core" of this SAN.

 

In each server cabinet, two 5424 switches dedicated to cabinet-level SAN traffic aggregation. 1x1gig from each server to each of the two 5424s in its cabinet (server NICs optimized for iSCSI, dedicated to SAN). The two cabinet aggregation switches trunked together by 1x1gig. Each 5424 cabinet switch trunked up to one of the "core" 6224s.

 

OK

 

• disable iSCSI optimisation on the 5424 switches
• if Jumbo Frames are supported on your server NICs and the NetApp , enable Jumbo Frames on all of the switches and on the server NIOCs and NETAPP NICs- on the 5424 I think its global, on the 6224 its on a port by port basis - the maximum MTU is 9216, but not everyone supports that - I'd suggest using an MTU of 9000
• if the server  NICs and the NETAPP  supports 802.3x flow control, enable it on the switches and on ther servers and NETAPP.
• configure the root bridge priority of one of the 6200s down to a low value, say 4096, and the other to 8192 - this will stop the root bridge wandering round the switches.
• configure the spanning tree link cost of the links between the 5424 within the cabinet to a higher value than the other links to ensure that this link normally blocks
• enable spanning tree portfast on the ports connected to the servers and on the LAG connected to the NETAPP.

One general point - you would get a real benefit if you stacked the 6224s; you would be able to configure a 4X1Gb agg, with two links on each switch, spanning tree would be much simpler, much higher bandwdith between the two 6224s.

 

Hope all this helps