The adminMode configuration attribute

The adminMode attribute is set with the mmchconfig command and can have one of two values:

allToAll

Indicates that all nodes in the cluster can be used for running GPFS administration commands and that all nodes are able to execute remote commands on any other node in the cluster without the need of a password.

The major advantage of this mode of operation is that GPFS can automatically recover missing or corrupted configuration files in almost all circumstances. The major disadvantage is that all nodes in the cluster must have root level access to all other nodes.

central

Indicates that only a subset of the nodes will be used for running GPFS commands and that only those nodes are able to execute remote commands on the rest of the nodes in the cluster without the need of a password.

The major advantage of this mode of administration is that the number of nodes that must have root level access to the rest of the nodes is limited and can be as low as one. The disadvantage is that GPFS might not be able to automatically recover from loss of certain configuration files. For example, if the SSL key files are not present on some of the nodes, the operator must intervene to recover the missing data. Similarly, it may be necessary to shut down GPFS when adding new quorum nodes. If an operator intervention is needed, you see appropriate messages in the GPFS log or on the screen.

Note List:

1. Any node that is used for the IBM Storage Scale GUI is considered as an administrative node and must have the ability to execute remote commands on all other nodes in the cluster without the need of a password as the root user or as the configured GPFS admin user.
2. If the GPFS cluster is configured to support Clustered NFS (CNFS), all CNFS member nodes must belong to the subset of nodes that are able to execute remote commands without the need of a password as the root user or as the configured GPFS admin user.
3. If the GPFS cluster is configured to support Clustered export services (CES), all CES member nodes must belong to the subset of nodes that are able to execute remote commands without the need of a password as the root user or as the configured GPFS admin user.
4. The IBM Storage Scale REST API must be configured on nodes that are able to execute remote commands without a password as the root user or as the configured GPFS admin user.
5. If an IBM Storage Protect server is used to back up the GPFS file system data, the nodes that are used as IBM Storage Protect clients must belong to the subset of nodes that are able to execute remote commands without the need of a password as the root user or as the configured GPFS admin user.
6. Windows GPFS clusters typically use central mode. allToAll mode requires that the GPFS Administrative service (mmwinserv) be configured to run as the special domain root account. For more information, see Procedure for installing GPFS on Windows nodes.
7. If Call home is configured to execute daily/weekly data gathering or the autoconfig option is to be used, the call home node (also known as call home server) must be able to reach call home clients without a password for scp data transfer as the root user or as the configured gpfs admin user.

You can change the mode of operations at any time with the help of the mmchconfig command. For example, to switch the mode of administration from allToAll to central, issue:

mmchconfig adminMode=central