iSLB vs. Traditional iSCSI

One of the most underutilized capabilities of the Cisco MDS seems to be its ability to do iSLB. The configuration of iSLB is transparent to the initiator, so initiators use standard iSCSI software such as Microsofts iSCSI client. The benefits of iSLB are great, both to high availability and the simplification of storage infrastructure. Some of the key benefits of iSLB:

Allows for the automatic creation of virtual targets, called initiator targets. You don’t have to create virtual targets. iscsi import target fc does not work with iSLB, but that’s not a real issue. With iSLB you get the ease of automatic virtual target creation combined with the flexibility of being able to determine which targets to create. You can also create lun maps and secondary pWWN’s at the same time, in the same CLI line even!

Allows for the automatic zoning of initiators with virtual targets. This is a huge benefit. Within the clause of the initiator you define the target which automatically gets zoned to the initiator. The name of the zone is automatically created and added to the zonesets for which the target is a member.

Distribution of iSLB static initiator configurations via CFS. This works hand and hand with VRRP. Just simply configure the static iSLB initiators on one switch and push it out to the rest of the switches.

Automatic load balancing of iSLB VRRP groups. This is a great feature. The iSLB initiators get load balanced automatically across all portals participating in the VRRP group. This maximizes availability and fabric resources. You can set a load amount on the initiator so that your initiators get weighted properly. Initiators which have more targets or more bandwidth needs you can set a higher weight on.

With all of these benefits, you are really getting all the best iSCSI has to offer, plus enhanced functionality, all with less configuration and an easier to manage fabric. If you are using iSCSI (as opposed to iSLB) you should really consider iSLB.

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