After yesterdays post on HBA’s I was thinking about fibre channel, which leads in nicely to todays post about fabric zoning best practices.
So, what is a ‘Single Initiator Zone’ and why do we implement them?
An initiator is the HBA in your ESXi Host, typically these are two port or perhaps in four port depending on your requirements. Each port is known as an initiator.
Part of your VMware design would be to have at least two HBA’s with two ports (initiators) for redundancy. These would then connect to the storage processor on your SAN (the target) which would have four ports, two on each disk controller.
We then have two fabric switches for redundancy to ensure that our SAN continues to recieve storage requests if a single fabric switch failes.
Following this through our ESXi Host has ports E1 & E2 on HBA1 and E3 & E4 on HBA2. The SAN has S1 & S2 on disk controller 1 and S3 & S4 on disk controller 2.
From this we will end up with eight zones, as each zone has a single initiator and single target.
E1 to S1 via Fabric Switch 1
E1 to S3 via Fabric Switch 2
E2 to S2 via Fabric Switch 1
E2 to S4 via Fabric Switch 2
E3 to S1 via Fabric Switch 1
E3 to S3 via Fabric Switch 2
E4 to S2 via Fabric Switch 1
E4 to S4 via Fabric Switch 2
If your like me, then looking at a picture makes a lot more sense
Brocade produce a ‘Fabric Zoning Best Practices’ White Paper, which is the paper I tend to follow when implementing fabric zoning.
The white paper can be found here
Don’t forget that Fabric Zoning has nothing to do with LUN masking which is used to choose which servers are allowed to see which LUN. For example in an vCenter environment you would normally want all of your hosts to be able to see all of the LUN’s for vMotion to work. The only expection to this would be if you had multiple clusters where you would LUN mask each clusters hosts.