AFM limitations

Active File Management (AFM) limitations are as follows:

  • If you change an AFM SW/IW home export from Kernel NFS or CNFS to the new IBM Spectrum Scale CES in 4.1.1 or later, AFM does not recognize the home. The best way to manage this situation is to run the mmafmctl failover command. See the IBM Spectrum Scale documentation for more details.
  • AFM RO/LU home export cannot be changed from Kernel NFS or CNFS to the new IBM Spectrum Scale CES in 4.1.1. or later.
  • Customers who enabled DMAPI/IBM Storage Protect for Space Management at the AFM home cluster must be running at RHEL 6.3, or later, or SLES 11 SP2, or later, on the cache cluster. There is a bug that is identified in earlier levels of RHEL, which requires that the exported path at home is excluded from DMAPI/IBM Storage Protect for Space Management. For more information, see IBM Support.
  • Code upgrade limitations:
    • If there are AFM filesets that use the Kernel NFS backend to communicate with a GPFS home that is running V4.1 or earlier, upgrading home to IBM Spectrum Scale V4.1.1 or later causes the AFM filesets to disable synchronization to home with a message as follows: 
      GPFS: 6027-3218 Change in home export detected. Synchronization with home 
is suspended until the problem is resolved
      Note: This upgrade affects only AFM filesets that were originally created with a GPFS home that runs V4.1 or earlier. This upgrade does not affect AFM filesets that were created with a home that runs IBM Spectrum Scale V4.1.1 or later. This issue is fixed in 4.1.1.4 and 4.2.0.1 available at Fix Central (IBM® Fix central).
  • AFM filesets do not support the gpfs API – gpfs_prealloc.
  • Due to a known issue with AFM SMB integration, the cache cluster might experience requeued messages on gateway nodes. As a result, SMB clients might experience a performance impact on data transfers.