Dirty region log alignment


Dirty region log alignment
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The location and size of each map within a dirty region log (DRL) must not violate the disk group alignment for the disk group (containing the volume to which the DRL is associated). This means that the region size and alignment of each DRL map must be a multiple of the disk group alignment, which for CDS disk groups is 8K. (Features utilizing the region size can impose additional minimums and size increments over and above this restriction, but cannot violate it.)

In a version 110 disk group, a traditional DRL volume has the following region requirements:

Minimum region size of 512K
Incremental region size of 64K

In a version 110 disk group, a version 20 DCO volume has the following region requirements:

Minimum region size of 16K
Incremental region size of 8K

Note:

The map layout within a Data Change Object (DCO) volume changed with the release of VxVM 4.0 to version 20. This can accommodate both FastResync and DRL maps within the DCO volume. The original version 0 layout for DCO volumes only accommodates FastResync maps.