Reasons to set fractional reserve to zero

Use case scenarios

You might want to set the fractional reserve to 0 on a volume that is a dedicated target for SnapMirror or SnapVault Snapshot copies of LUNs. For example, the volume might be on a NearStore system for long-term retention. You mount the LUN Snapshot copy only for data recovery purposes. This means the rate of change in this volume is low, and you can set the fractional reserve to 0 to provide more usable space. You set the fractional reserve option to 0 in this case if maintaining usable space is your priority because if you do a large number of write operations during the recovery process and the volume runs out of space, the LUN will go offline.