Disaster recovery setup problems

The following setup problems might impact disaster recovery implementation:

  1. Considerations of data integrity require proper setup of PPRC consistency groups in PPRC environments. Additionally, when using the FlashCopy® facility, make sure to suspend all I/O activity before generating the FlashCopy image. See Data integrity.
  2. In certain cases, it might not be possible to restore access to the file system even after relaxing the node and disk quorums. For example, in a three failure group configuration, GPFS tolerates and recovers from a complete loss of a single failure group (and the tiebreaker with a quorum override). However, all disks in the remaining failure group must remain active and usable in order for the file system to continue its operation. A subsequent loss of at least one of the disks in the remaining failure group would render the file system unusable and trigger a forced unmount. In such situations, users might still be able to perform a restricted mount and attempt to recover parts of their data from the damaged file system. For more information on restricted mounts, see Restricted mode mount.
  3. When you issue mmfsctl syncFSconfig, you might get an error similar to the following: 
    mmfsctl: None of the nodes in the peer cluster can be reached

    In such scenarios, check the network connectivity between the peer GPFS clusters and verify their remote shell setup. This command requires full TCP/IP connectivity between the two sites, and all nodes must be able to communicate by using ssh or rsh without the use of a password.