ESX 3.5 and iSCSI configuration with NIC's

[fixxervi6]

I have a server wih 4 NIC's that I want to dedicate to iSCSI interfaces, it seams that ESX will only allow me to create one interface, then tie all the nics to that one vm switch then assigne one IP, is this standard practice or shoudl I be able to configure each nic with its own IP? I'm not sure how multi pathing works through the ESX software initiator.

Second part is, how can I be sure the software initiator is running jumbo frames?

[mike_laspina · Accepted solution]

Hello,

The iSCSI software initiator only allows for NIC teaming, multipathing is only supported on iSCSI hardware adaptors specifically QLogic 40xx is a safe bet.

Second Q. The software initiator does not support them. Jumbo frames are an all or nothing venture which must be configured form end to end or it fails, I do not use it currently use them, but a sniffer will reveal its function.

Message was edited by: mike.laspina

[ssumichrast]

I'm hoping to get around this limitation by creating two iSCSI networks -- I'm going to have 3 LeftHand SANs at my disposal in the environment, and two stacked Cisco switches. I'm going to team two Gb NICs together across the stacked switches -- I Could lose a switch or cable and keep going. I'll have two teams of two, and each will point to seperate LUNs, which should hopefully get me the bandwidth I want, plus failover.

There's supposed to be multipathing support coming out for the initiator, if I remember correctly from the VMware Class. Also, I wasn't aware jumbo frames weren't supported by the software initiator. Hopefully we'll see that in an upcoming release.

[mike_laspina]

Software iSCSI does come at a price on your ESX resource, strait iSCSI overhead will hit the CPU anywhere from 5 to 30% research has show that to maintain 1Gbit sustained large block I/O a 1.5Ghz CPU would experiance a 100% load. So you need to account for this overhead. Fortunately today's CPU is usually not the system bottle neck for an ESX Server and it is quite viable to use Software iSCSI without excessively impacting the server resources. Most appliance based iSCSI SAN engines will not have enough performance to drive the networks 2Gbit of bandwidth. This is mainly due to the low numbers of drives that are normally configured in them. For example a single Lefthand Networks NSM160 maximum transfer capability is 200MB/s thus an FDX 1GBit line is sufficient, of course two should be used for fault tolerance.

[fixxervi6]

Everywhere I read it says ESX 3.5 support jumbo frames, I don't see anywhere in the GUI where to turn this on, I assume its a CLI deal.

However if I can't use more than one NIC then its pointless anyway as my SAN will easily saturate a single NIC.

So I guess its back to HBA's