How PowerVC sets up Fibre Channel switch zoning

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A storage controller typically contains a pair of redundant controller nodes, but some types of storage providers might have many more. The virtual machine must have I/O paths to both controller nodes so that operations are not interrupted if a controller node fails. When a virtual machine is created, IBM® Power® Virtualization Center creates these paths between the virtual machine and the storage. The zones are created with the prefix powervc_ unless you use the command powervc-config storage zone-name-prefix to set a different prefix.

Notes:
  • For IBM SVC and DS8000 storage devices, PowerVC tries to set up zoning only when the initial volume is attached to the virtual machine.
  • The images below illustrate an IBM Storwize® environment with NPIV.
  • The storage connectivity group being used can specify a subset of the registered fabrics that will apply to NPIV zoning.
  • An NPIV adapter on PowerVM® is actually two ports. One port is the active port used by the virtual machine for normal IO traffic. The other is a migration port that is used during LPM operations. Both ports are zoned, therefore there are actually twice as many zones created than are shown in the examples below.
  • By default, for storage controllers other than Storwize, each virtual machine NPIV port is zoned to one target port on the controller. If you have multiple (non-Storwize) storage controllers and want to ensure that one target from each controller is zoned, you could use port groups and powervc-config storage fc-zone zone-one-target -false. For information about port groups, see Configuring storage port groups.

Which ports are available for zoning?

Frequently, not all ports attached to a storage controller are actually available to be used for zoning. There are several settings that specify which ports can be used:
  1. If you deployed the virtual machine with a storage template that specifies one or more port groups, one of the port groups are chosen and the ports within that group are used in deployment.
  2. If there is no port group associated with the virtual machine, only ports listed in the global port whitelist are available.
  3. If there is no port group and no whitelist, then all ports are available.

One fabric, one Virtual I/O Server

In this situation, PowerVC zones the initiator port to one target port on each storage controller node.

This image shows the setup that is described in the previous paragraph.

One fabric, two Virtual I/O Servers

In this situation, PowerVC zones both initiator ports to one target port on each storage controller node. This creates four paths to the storage device and four zones.

This image shows the setup that is described in the previous paragraph.

Two or more fabrics, one Virtual I/O Server

In this situation, PowerVC zones one initiator port on each fabric to one target port on each storage controller node. It is assumed that both storage controller nodes have a port on each fabric. This creates four paths to the storage device and four zones; two zones for each fabric. In this illustration, two fabrics are shown. The same design applies to more than two fabrics.

This image shows the setup that is described in the previous paragraph.

Two or more fabrics, two Virtual I/O Servers

In this situation, PowerVC zones the initiator port on one fabric to one target port on one storage controller node. PowerVC zones the other initiator port on the same fabric to the other storage controller node. The same is done on the other fabric. This creates four paths to the storage device and four zones; two zones for each fabric. In this illustration, two fabrics are shown. The same design applies to more than two fabrics.

This image shows the setup that is described in the previous paragraph.

Multipath zoning

You can use the default zoning or multipath zoning when volumes are attached with NPIV connectivity. With default zoning, at most one port per fabric on each storage controller node is zoned to each virtual machine port. With multipath zoning, all available WWPNs are used for attachment. This means that, for each storage controller node, all target ports that are active on registered fabrics are zoned to all of the virtual machine ports. This creates the maximum number of paths to the storage device. Using multipath zoning increases volume availability and potentially increases parallel storage traffic, but it also creates more zones in the fabric.

To enable multipath zoning on Storwize drivers, select Use all WWPNs for attachment on the storage template. To enable multipath zoning on all other drivers, set powervc-config storage fc-zone zone-one-target -false.

In this illustration, multipath has been enabled in an environment with one fabric and one Virtual I/O Server. PowerVC zones each initiator port to all the target ports on the fabric on each storage controller node. The number of zones created depends on the number of target ports connected to the fabric from each storage controller node. In his illustration there are four target ports connected to the switch on each storage controller node which would result in 16 zones being created for each Fibre Channel port in the virtual machine.
This image shows the setup that is described in the previous paragraph.