Conditions that can trigger a corrective action

PowerHA® SystemMirror® shared volume group time stamps are not up-to-date on a node

If the shared volume group time stamp file does not exist on a node, or the time stamp files do not match on all nodes, the corrective action ensures that all nodes have the latest up-to-date VGDA time stamp for the volume group and imports the volume group on all cluster nodes where the shared volume group was out of sync with the latest volume group changes. The corrective action ensures that volume groups whose definitions have changed will be properly imported on a node that does not have the latest definition.

The /etc/hosts file on a node does not contain all PowerHA SystemMirror-managed IP addresses

If an IP label is missing, the corrective action modifies the file to add the entry and saves a copy of the old version to /etc/hosts.date. If a backup file already exists for that day, no additional backups are made for that day.

Verification does the following:

• If the /etc/hosts entry exists but is commented out, verification adds a new entry; comment lines are ignored.
• If the label specified in the PowerHA SystemMirror Configuration does not exist in /etc/hosts , but the IP address is defined in /etc/hosts, the label is added to the existing /etc/hosts entry. If the label is different between /etc/hosts and the PowerHA SystemMirror configuration, then verification reports a different error message; no corrective action is taken.
• If the entry does not exist, meaning both the IP address and the label are missing from /etc/hosts, then the entry is added. This corrective action takes place on a node-by-node basis. If different nodes report different IP labels for the same IP address, verification catches these cases and reports an error. However, this error is unrelated to this corrective action. Inconsistent definitions of an IP label defined to PowerHA SystemMirror are not corrected.

A file system is not created on a node, although disks are available

If a file system has not been created on one of the cluster nodes, but the volume group is available, the corrective action creates the mount point and file system. The file system must be part of a resource group for this action to take place. In addition, the following conditions must be met:

• This is a shared volume group.
• The volume group must already exist on at least one node.
• One or more node(s) that participate in the resource group where the file system is defined must already have the file system created.
• The file system must already exist within the logical volume on the volume group in such a way that simply re-importing that volume group would acquire the necessary file system information.
• The mount point directory must already exist on the node where the file system does not exist.

The corrective action handles only those mount points that are on a shared volume group, such that exporting and re-importing of the volume group will acquire the missing file systems available on that volume group. The volume group is varied off on the remote node(s), or the cluster is down and the volume group is then varied off if it is currently varied on, prior to executing this corrective action.

If Mount All File Systems is specified in the resource group, the node with the latest time stamp is used to compare the list of file systems that exists on that node with other nodes in the cluster. If any node is missing a file system, then PowerHA SystemMirror imports the file system.

Disks are available, but the volume group has not been imported to a node

If the disks are available but the volume group has not been imported to a node that participates in a resource group where the volume group is defined, then the corrective action imports the volume group.

The corrective action gets the information regarding the disks and the volume group major number from a node that already has the volume group available. If the major number is unavailable on a node, the next available number is used.

The corrective action is only performed under the following conditions:

• The cluster is down.
• The volume group is varied off if it is currently varied on.
• The volume group is defined as a resource in a resource group.
• The major number and associated PVIDS for the disks can be acquired from a cluster node that participates in the resource group where the volume group is defined.

Note: This functionality will not turn off the auto varyon flag if the volume group has the attribute set. A separate corrective action handles auto varyon.

Shared volume groups configured as part of a PowerHA SystemMirror resource group have their automatic varyon attribute set to Yes.

If verification finds that a shared volume group inadvertently has the auto varyon attribute set to Yes on any node, the corrective action automatically sets the attribute to No on that node.

Required /etc/services entries are missing on a node.

Required PowerHA SystemMirror snmpd entries are missing on a node

If a required entry is commented out, missing, or invalid on a node, the corrective action adds it.

In /etc/snmpdv3.conf or /etc/snmpd.conf, the required PowerHA SystemMirror snmpd entry is:

smux   1.3.6.1.4.1.2.3.1.2.1.5   clsmuxpd_password # PowerHA SystemMirror/ES for AIX clsmuxpd

In /etc snmpd.peers, the required PowerHA SystemMirror snmpd entry is:

clsmuxpd   1.3.6.1.4.1.2.3.1.2.1.5 "clsmuxpd_password" # PowerHA SystemMirror/ES for AIX clsmuxpd

If changes are required to the /etc/snmpd.peers or snmpd[v3].conf file, PowerHA SystemMirror creates a backup of the original file. A copy of the pre-existing version is saved prior to making modifications in the file /etc/snmpd.{peers | conf}.date. If a backup has already been made of the original file, then no additional backups are made.

PowerHA SystemMirror makes one backup per day for each snmpd configuration file. As a result, running verification a number of times in one day only produces one backup file for each file modified. If no configuration files are changed, PowerHA SystemMirror does not make a backup.

Required PowerHA SystemMirror network options setting

The corrective action ensures that the value of each of the following network options is consistent across all nodes in a running cluster (out-of-sync setting on any node is corrected):

• tcp_pmtu_discover
• udp_pmtu_discover
• ipignoreredirects

Required routerevalidate network option setting

Changing hardware and IP addresses within PowerHA SystemMirror changes and deletes routes. Because AIX caches routes, setting the routerevalidate network option is required as follows:

no -o routerevalidate=1

This setting ensures the maintenance of communication between cluster nodes. Verification run with corrective action automatically adjusts this setting for nodes in a running cluster.

Corrective actions when using IPv6

If you configure an IPv6 address, the verification process can perform 2 more corrective actions:

• Neighbor discovery (ND). Network interfaces must support this protocol which is specific to IPv6. The underlying network interface card is checked for compatibility with ND and the ND related daemons will be started.
• Configuration of Link Local addresses (LL). A special link local (LL) address is required for every network interface that will be used with IPv6 addresses. If a LL address is not present the autoconf6 program will be run to configure one.