Creating an AFM-based DR relationship

Use this procedure to create and use an AFM-based Async DR relationship:

1. Create a primary fileset. Run on a primary cluster.

   Create the primary fileset by using the mmcrfileset command. The primary can be connected to the secondary using NFSv3 protocol or the NSD protocol. All AFM parameters for writable filesets (single writer or independent writer) are applicable to a primary fileset. A primary fileset is not revalidated and does not check the secondary for changes because it is expected that changes always originate from the primary.

   A primary fileset is a writable fileset. Therefore, all file operations that are performed on this fileset are replayed at the secondary fileset by using the same mechanism as single writer and independent writer modes. Unlike other AFM modes the secondary, or target fileset is an AFM fileset that has a relationship with a primary. The secondary fileset is enforced as read-only. AFM parameters such as afmAsyncDelay, number of flush threads, and parallel write can be used on primary filesets.

   When a primary fileset is created, a unique primary ID is generated. When you create a primary fileset, you need to specify the path to the secondary fileset though it might not exist at the time of primary creation. In the following example, the secondary is not created but the path is provided in mmcrfileset command.

   # mmcrfileset fs1 primary2 -p afmMode=primary --inode-space=new -p
   afmTarget=nfs://c2m3n06/ibm/fs1/secondary2 -p afmRPO=720
   Fileset primary2 created with id 19 root inode 7340035.
   Primary Id (afmPrimaryID) 15997179941099568310-C0A8747F557F0086-19

   Note: If you are using CES NFS at home, replace c2m3n06 with ces_ip_of_secondary_node.
2. Create a secondary fileset. Run on a secondary cluster.

   Get the primary ID of the GPFS fileset on the primary side (afmPrimaryID) before the actual conversion. Use mmafmctl getPrimaryId command on the GPFS fileset on the primary side.

   # mmafmctl fs1 getPrimaryId -j primary2
   Primary Id (afmPrimaryID) 15997179941099568310-C0A8747F557F0086-19
   

   Create a secondary fileset by using the mmcrfileset command.

   mmcrfileset fs1 secondary2 -p afmMode=secondary –p
   afmPrimaryID=15997179941099568310-C0A8747F557F0086-19
   --inode-space new

3. Link the secondary fileset on the secondary cluster by using the mmlinkfileset command.

   Run mmlinkfileset fs1 secondary2 -J /ibm/fs1/secondary2.

   The primary does not check the secondary for changes. If you are using quotas, ensure that the same value is set for quotas on primary and secondary. On a primary fileset, eviction is disabled by default and filesets do not expire. If you are using NFS, ensure that the NFS export on the secondary site is accessible from the gateway nodes in the primary cluster. If you are using the NSD protocol, the secondary file system needs to be mounted on the gateway nodes at the primary cluster.

4. Restart NFS on secondary.
   Note: If you are using CES NFS, you need not to restart NFS.
5. Link the primary fileset on the primary cluster.
   Link the primary fileset by using mmlinkfileset command. Linking the fileset creates the first RPO snapshot on the primary called psnap0.

   mmlinkfileset fs1 primary2 -J /ibm/fs1/primary2

   After the primary and secondary are linked, the RPO snapshot (psnap0) gets queued from the primary fileset, which gets replayed on the secondary fileset. The Async DR filesets are now ready for use.