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Setting Major and Minor Numbers
2-13
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
Major number
You set a common major number for every host in the cluster during
PowerPath installation (refer to Chapter 1, Installing PowerPath).
Setting a Common
Minor Number
Minor numbers are assigned as follows:
◆ 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
-removePaths option.
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.