EMC 300-000-978 REV A03 manual Setting Major and Minor Numbers

PowerPath in a Cluster Environment

Setting Major and Minor Numbers

With NFS in a cluster environment:

◆ The PowerPath driver, emcp, must use the same major number on every node in the cluster.

◆ Every PowerPath Volume Manager volume in the cluster must use the same minor number on every node in the cluster.

Otherwise, you may need to restart NFS clients when failover or failback occurs.

Setting a Common You set a common major number for every host in the cluster during

Major number PowerPath installation (refer to Chapter 1, Installing PowerPath).

Setting a Common Minor numbers are assigned as follows:

Minor Number

◆ When you create a PowerPath Volume Manager volume, a minor number is assigned to that volume on the host where the volume is created.

◆ When you then test failover on the nodes in the cluster, a minor number is established for every failover host in the cluster.

After you test failover, and before you start to use the new volume, you must ensure that the volume has the same minor number on every node in the cluster. To do so, use the following procedure:

The commands in this procedure work whether the volume is imported or deported. Note, however, that deports must be done without using the -removePathsoption.

1. On each node in the cluster, run the powervol getminor command to determine the minor number assigned to the volume on that node. Refer to the powervol(1) man page for information on powervol getminor.

2. If step 1 reveals inconsistent minor numbers, use the emcpminor command to find one minor number that can be used for the volume on every host. Refer to the emcpminor(1) man page for information on emcpminor.

While running emcpminor, avoid running any other commands that might claim minor numbers.

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