Converting GPFS filesets to AFM DR

This topic lists the steps to convert GPFS™ independent filesets to primary or secondary filesets.

1. Ensure that primary and secondary sites have the same data using trucking method.

   An existing GPFS independent fileset can be converted to primary or secondary. If the fileset on the primary site has data, the secondary site must be synchronized with the same data. This process is termed as trucking. Trucking must be inband.

   Inband trucking: Copying the data from the primary to the secondary while setting up the relationship. Inband trucking is limited by the network bandwidth between the primary and the secondary.

   Conversion of a regular independent fileset to AFM primary with mmafmctl command must be performed by specifying the --check-metadata option that verifies that the fileset does not contain objects with attributes that are disallowed in a primary fileset. These include the following:

   • Files with Immutable and AppendOnly attributes
   • Special files (such as devices)
   • Dependent fileset
   • Clones where the source belongs to a snapshot
2. Get the primary id of the GPFS fileset before the actual conversion by using the mmafmctl getprimaryid command on the GPFS fileset.
3. Convert the fileset on the secondary site to a secondary and set the primary id using the mmchfileset or mmafmctl command with the convertToSecondary option.

   Ensure that the NFS export on the secondary site is accessible on the primary, if NFS is used for defining AFM target on primary site. If GPFS protocol is used for the target, the secondary file system should be remote mounted on the primary site.

   Note: If you are establishing the secondary using the out-of-band option, you must first complete the data copy and ensure that the primary and the secondary have the same data before you configure the secondary with the primary's unique ID.
4. Restart NFS on the secondary.
5. Convert the fileset on the primary site to a primary by using mmafmctl command. Run on the primary cluster. Gateway nodes must be defined in the primary site and the file system must be mounted on all gateway nodes before doing this conversion. Run mmafmctl with convertToPrimary option.

   mmafmctlDevice convertToPrimary-j FilesetName 
   [ --afmtarget Target { --inband | --secondary-snapname SnapshotName }] 
     [ --check-metadata | --nocheck-metadata ] [--rpo RPO] [-s LocalWorkDirectory

   --afmtarget and --inband are mandatory options for the first conversion command on the fileset. Conversion can get interrupted in the middle due to unforeseen reasons or in case of rare errors when psnap0 creation is not successful. In such cases, fileset is converted to a primary but left in PrimInitFail state.

   Based on the reason behind the failure, the administrator must re-run the conversion command without any argument. Alternatively, the fileset can be converted back to normal GPFS filesets and converted again using the conversion command with arguments.

   The --afmtarget option mentions the fileset path on the secondary site.

   The --inband option is used for inband trucking. Primary id gets generated and the first RPO snapshot psnap0 gets created. The entire data on the snapshot is queued to the secondary. Once the data has replayed on the secondary after Step 3 (following), that is, the primary and secondary are connected, it creates a psnap0 on the secondary ensuring that the psnap0 on the primary and the secondary are the same. At this point, one can consider a relationship has been established.

   The --check-metadata option checks if the disallowed types (like immutable/append-only files, clones where the source belongs to a snapshot etc) are present in the GPFS fileset on the primary site before the conversion. Conversion fails with this option if the disallowed types still exist on the primary side. --check-metadata is not mandatory and performs a scan of the entire fileset to verify its contents, and while it can be excluded if the fileset is known to be permissible for conversion, it should be used when in doubt. This is the default option.

   The --no check-metadata option is used to proceed with conversion without checking for the disallowed types.

   The --rpo option specifies the RPO interval in minutes for this primary fileset. By default, RPO is disabled. You can use the mmchfileset command to modify the afmRPO value of the AFM DR fileset. The --secondary-snapname is not applicable for converting AFM or GPFS filesets. This option is used while establishing a new primary, as discussed in subsequent sections.

   Gateway node assignments must be finalized and done preferably before conversion of GPFS or AFM filesets to primary. If no gateway is present on the primary cluster during conversion, then primary fileset might remain in the PrimInitFail state.