Restrictions on the number of PGR Keys

Nondisruptive Migration User Guide

Version
9.6.0
Audience
anonymous
Part Number
MK-92RD8086-11

A PGR Key is used when the SCSI-3 Persistent Reserve command of the SCSI standard is executed. When a USP V/VM is configured as a source storage system, you must set the number of PGR Keys per port to be less than or equal to 128. In a Microsoft Failover Cluster (MSFC) configuration using Windows Server 2008 or Windows Server 2008 R2, you must calculate the number of PGR Keys for each port as described here.

How to calculate the number of PGR Keys

If the LU is the Cluster Shared Volume (CSV) which can be configured by Hyper-V and MSFC in Windows Server 2008 R2, you can calculate the number of PGR Key by the following calculation formula, because all nodes register a different PGR Key for each LU:

Number of PGR Keys per port = number of connecting nodes × number of LUs ≤ 128

If the LU is a MSFC configuration LU of Windows Server 2008 or Windows Server 2008 R2, you can calculate the number of PGR Keys by the following formula, because the number of PGR Keys becomes two for the one LU when a failover is caused by server failure:

Number of PGR Keys per port = number of LUs + 32 ≤ 128

For server cluster configurations other than above, the number of PGR Keys is roughly equal to the number of nodes:

Number of PGR Keys per port ≈ number of connecting nodes ≤ 128

Confirm the number of PGR Keys is less than or equal to 128 in the migration storage system (USP V/VM).

Configuration example

The following figure shows the configuration example of the migration source storage system (USP V/VM) using the PGR Key.

Because the maximum number of PGR Keys is 128 per port, you must configure the system within 128 for the each host group, even if multiple host groups are assigned to the ports (like the C2 and C3 port in the figure).