Question: How many IP address assignments do I need for my Dual Controller HA Compellent iSCSI SAN?
Scenario: Working with the Dell Enterprise Deployment Team (EDT) on a Compellent iSCSI SAN implementation as a Solutions Integrator, and integrating with a VMware vSphere environment.
The I/O cards we have in each SC8000 controller are: 2 x dual port 10 GbE cards, and 1 x dual port 1 GbE card. The 10 GbE cards are used for iSCSI traffic to VMware hosts and external physical servers accessing the iSCSI SAN. The 1 GbE cards are used for iSCSI replication traffic.
Fig. 1: Connections to a Dual Controller HA Compellent iSCSI SAN
In the diagram below, we split the 10 GbE iSCSI NICs into Fault Domain A, and Fault Domain B. We also have have the 1 GbE iSCSI NICs as Fault Domain R (for Replication.) Also, notice we have circled the Eth0 Management connections.
Fig. 2: HA Compellent iSCSI Controllers with Fault Domains
Controller A will have one iSCSI IP in Domain A (which will “float” across the two available NICs,) one iSCSI IP in Domain B (which will similarly “float”,) and one iSCSI IP in Domain R (again “floats”); also, we have iDRAC and Eth0 Management IPs. Controller B will be similarly configured. Then Fault Domain’s A and B (the 10 GbE iSCSI) will have one Virtual IP, fault domain R (the 1 GbE replication iSCSI) will have one Virtual IP, and there will be one Virtual IP for Management.
Note: iSCSI Fault Domain’s A and B are not different subnets.
Note: This is using virtual ports mode as opposed to legacy mode.
The 13 IPs required are illustrated with the table below.
Fig 3: Table for IPs required for a Dual-Controller HA Compellent iSCSI SAN solution
Final Word: As always, comments most welcome, especially since it took me a little while to get my head around this!