Release Notes

12 Dell PS Series: Space Borrowing for Snapshots and Replicas | TR1084 | version 2
3 Space borrowing with thin provisioned volumes and SCSI UNMAP
Snapshot reserve is defined as a percentage of volume reserve. If the volume size changes, the snapshot reserve also
adjusts automatically. With thin provisioned volumes using SCSI UNMAP (with Microsoft Windows, VMware ESXi, or
Red Hat Linux) where the PS Series volume size shrinks as a result of data being deleted on the volume from the
operating system, snapshot reserve will also shrink. Without space borrowing enabled, this can potentially lead to older
snapshots being deleted, if the reserve space becomes entirely consumed.
Note: As a best practice, disable support for UNMAP from the operating system on hosts that are using Dell PS Series
volumes configured for replication (both asynchronous and synchronous).