Disabling AFM

An AFM fileset can be disabled and converted to a GPFS-independent fileset. However, GPFS-independent fileset cannot be converted to an AFM fileset.

Before you disable the AFM fileset, ensure that afmShowHomeSnapshot value is set to no on the specific AFM fileset. If afmShowHomeSnapshot is set to yes then you can modify the afmShowHomeSnapshot value by using mmchfileset command. After the value of afmShowHomeSnapshot is set to no you can proceed to disable the AFM fileset.

Issue the following command to set afmShowHomeSnapshot value to no:
mmchfileset fs1 ro2 -p afmShowHomeSnapshot=no
The preceding command gives the output similar to the following as shown here:
mmlsfileset fs1 Fileset ro2 changed

To dissociate home and cache relationship of an AFM fileset, you can convert the AFM fileset to an independent fileset by using the mmchfileset -p afmTarget=disable command. Thereafter, the fileset is a GPFS or IBM Storage Scale-independent fileset and requests are not queued to home. An example is the case of NFS migration, where AFM fileset must be disabled after migration.

You must disable AFM filesets while the filesets are linked. In some cases, disabling of AFM fileset might fail with an error message.

Complete the following steps to disable an AFM fileset -
  1. If the fileset is unlinked, run mmlinkfileset gpfs0 FilesetName -J gpfs0/FilesetName to link the fileset.
  2. Run mmchfileset gpfs0 FilesetName -p afmTarget=disable.

    The following warning message displays - Warning! Once disabled, AFM cannot be re-enabled on this fileset. Do you wish to continue? (yes/no)

    Enter yes.

    The following warning message displays - Warning! Fileset should be verified for uncached files and orphans. If already verified, then skip this step. Do you wish to verify same? (yes/no)

    Enter yes.

    • If error conditions are not found, the following message displays:

      File system gpfs0 is mounted on n nodes or fileset FilesetName is not unlinked.

      Unlink the fileset and run mmchfileset gpfs0 FilesetName -p afmTarget=disable again. Enter no to the warning message about verification of the fileset. The AFM fileset is disabled.

    • In case of error conditions, disabling AFM fileset fails. See the following table for the error conditions with the corresponding messages.

      Table 1. Conditions in which disabling AFM fileset fails, with corresponding messages
      Condition Error message
      Incomplete directories present mmchfileset: 6027-2307 [E] Uncached files present, run prefetch first.
      Uncached files present Uncached files present, run prefetch first using policy output: /var/mmfs/tmp/cmdTmpDir.mmchfileset.18149/list-file.mmchfileset.18149
      Orphans present Orphans are present, run prefetch first using policy output: /var/mmfs/tmp/cmdTmpDir.mmchfileset.18149/list-file.mmchfileset.18149
      You must run prefetch as suggested in the message to fix the error condition.
  3. If uncached files or orphans are present, run prefetch by using the following command:
    mmafmctl gpfs0 prefetch -j FilesetName --list-file /
var/mmfs/tmp/cmdTmpDir.mmchfileset.18149/list-file.mmchfileset.18149
  4. If incomplete directories are present, generate a list file to prefetch the uncached files first. Use this generated list file that contains uncached file entries to run the command - mmafmctl gpfs0 prefetch -j FilesetName --list-file list file path. Here, list file path is the generated list file.
  5. Ensure that all data in the AFM fileset is prefetched.
  6. Run step 2 again and complete disabling AFM fileset.