Having a powerful Unified Storage array like the EMC VNX offers many different capabilities, and an equal number of decisions. The majority of the implementations we do of these boxes are around VMware/virtualization, and in today's leading hypervisors you can provide storage through Fiber Channel, Fiber Channel over Ethernet, iSCSI, or NFS for NAS devices. And of course, the EMC VNX gives you the option for any / all of the above.

Within the context of virtualization for the majority of this post, I'll lay out the best practices for configuration of the VNX and network between the host and the storage, and go a bit further where applicable.

Personal experience has shown that Fiber Channel is still the most common choice customers are making for their storage network / connectivity. When providing storage off of the EMC VNX through Fiber Channel, it's very common to find an upstream Cisco or equivalent fiber switch.

Connectivity for the VNX through Fiber Channels comes off of the "block" side of the array, through either the ports on the Storage Processor Enclosure itself, or one of the many IO modules connecting to each Storage Processor. If you "direct attach", meaning plug your host HBAs into the VNX directly, the array will recognize the host and you will be able to present storage without issues. However, this does not scale, as you're using the backend ports for host connectivity, and would be limited the number of ports available per SP.

This is why most environments have a switch that connects to these ports, and then "fan out" the hosts through connectivity to the switch(es).

iSCSI

iSCSI connectivity on the VNX should be done ONLY through the Storage Processors, and NOT through the X-Blades. There are many reasons for this that I won't get into-- and in the past you could do iSCSI that was file system based. Long story short, don't do it.

Also, a common practice in the past was to have the iSCSI storage processor ports on separate subnets. With 2 ports per SP, it was normal to see 1 port from each on Subnet A, and the other ports on Subnet B (so each SP had a single connection in each VLAN). This was due to a "bug" or software limitation that was removed/resolved on the CLARiiON platform staring with FLARE 30.

Today if you are implementing iSCSI off of the VNX, the ports should all be in the same VLAN. This makes the design much simpler, and it works great (both for 1Gb and 10Gbe).

Assuming you are connecting the VNX to upstream switches, it's important to keep in mind that you want to physically separate this traffic from the rest of the network (meaning dedicated Ethernet switches) where possible, but at the very least logically separate it through VLANs.

The ports in which the storage processor connect to the switch should have spanning-tree disabled or bypassed through use of spanning-tree portfast (or switchport type edge trunk for the Nexus guys). Quick explanation of what this does