Restoring the locality for files with WADFG

If you want to control the location of the first replica, second replica, and the third replica, set the WADFG attributes of the files via mmchattr. If you are using IBM Storage Scale 4.1.1.0 or earlier, perform these steps to restore the data locality.

1. Decide the location for data replica.
2. Run mmchattr --write-affinity-failure-group to set/update the new WADFG of the file Step.

   In IBM Storage Scale 4.2.2.0 and later, mmrestripefile -l is optimized to reduce unnecessary replica data movement. For example, the original WADFG is (1;2;3). If it is changed into (4;2;3), mmrestripefile -l moves only the first replica of all blocks. However, if it is changed into (4), mmrestripefile -l might move the second and third replica. Therefore, changing the original WADFG from (1;2;3) into (4;2;3) is better than changing it into (4).

3. If you are using IBM Storage Scale 4.1.1.0 or later, skip this step. Run mmrestripefile –l filename or mmrestripefile –b filename.

   In IBM Storage Scale 4.1.1.0 and later, the default option for mmchattr is -I yes, and the restripe function of mmrestripefile -l is performed when mmchattr is run.

4. Check the data locality.