Storage Connectivity Groups (SCGs) are a critically important part of PowerVC when managing PowerVM-based systems. If you’re unfamiliar with SCGs, please take a look at the official documentation on the PowerVC Knowledge Center as this assumes you’re already somewhat familiar with the construct.
SCGs received some very useful updates in PowerVC 1.2.2 (listed in no particular order):
Ability to specify connectivity types for boot volumes and data volumes
Now that PowerVC supports vSCSI, NPIV and Shared Storage Pool (SSPs) attachment models, you can configure various attachment types that PowerVC will use for boot and data volumes.
Ability to specify NPIV fabric access requirements
PowerVC has always supported running with single fabrics, single VIO Server, dual fabrics, dual VIO Servers, or any combination thereof. The problem was that you couldn’t particularly guarantee certain “minimal” connectivity requirements would be met; this option gets you one step closer to imposing dynamic storage options. You can select from:
* Dual – VM requires dual fabric connectivity for each VIO Server that hosts VM virtual Fibre Channel connections
* Dual per VIOS – VM requires connectivity to two fabrics, but can use different VIO Servers to satisfy the requirement
* Fabric A – Always connect to Fabric A
* Fabric B – Always connect to Fabric B
* Single – Connect to a single fabric only; no preference as to which fabric is selected
Ability to specify VIO Server Redundancy Requirements
You can now configure the SCGs to specify rules such as “Connect to exactly X VIO Servers” or “Connect to at least X VIO Servers”.
Using the new connectivity options above, you can create a much more dynamic storage connectivity scheme that will leave you knowing your storage connectivity policies can be satisfied (i.e., the VM placement operation would otherwise fail should your connectivity requirements not be satisfied).
Take a look at the screen shot below for a first-hand look of these options. Now–go off and enjoy SCGs today!
Figure 1: Storage Connectivity Groups in PowerVC 1.2.2