Release Notes

20 Dell PS Series: Space Borrowing for Snapshots and Replicas | TR1084 | version 2
5 Space borrowing examples
5.1.1 Space borrowing with snapshots
In the following example, a 10 GB thick volume is configured with 100% (10 GB) of snapshot reserve.
As snapshot borrowing is enabled on the volume, it is possible for the snapshot space to exceed the configured 10 GB
snapshot reserve for the volume. In the example below, the full 10 GB of configured snapshot reserve space is being
used, two additional GB are borrowed from the storage pool. A total of 12 GB of snapshot space is used. If snapshot
space borrowing was not enabled, it would not be possible for the snapshot space to exceed the initially configured 10
GB limit.
Note: Because snapshot reserve is a percentage of the volume reserve, the amount of snapshot reserve space
fluctuates in direct proportion to a thin-provisioned volume reserve when data is dynamically written and deleted (for
example, when invoking SCSI UNMAP from Microsoft Windows, VMware ESXi or Red Hat Linux — see section 3).