Release Notes

15 Dell PS Series Snapshots and Clones: Best Practices and Sizing Guidelines | BP1027
action is to delete the oldest snapshot, providing the necessary free space to create a new snapshot.
However, the user can set a policy for recovering snapshot space with the following options:
• Delete oldest snapshot (default).
• Set the base volume and its snapshots offline.
If a snapshot has active iSCSI connections, they will be terminated before the snapshot is deleted or before
the volume and its snapshots are set offline. Administrators can also monitor snapshot usage and prevent the
loss of snapshot data due to automatic snapshot deletion by cloning the snapshot or increasing the snapshot
reserve space. While deleting a snapshot does not result in deleting any data from the base volume, it does
remove the ability to restore the base volume to that specific point in time.
3.6 Creating a clone volume
When a clone volume is created, it is a complete copy of the base volume. Unlike the snapshot volume, it no
longer shares any data with the base volume. Since it is an independent copy of that base volume it does not
use snapshot reserve. Initially, a clone must be created in the same pool as the base volume. However, it can
subsequently be moved to any pool with adequate free space. If the base volume is a thin provisioned
volume, a clone of that volume will also default to be thin provisioned and will initially report the same size and
space utilization as the base volume.
3.7 Creating a template volume and thin clones
Any volume can be designated as a template volume. When a volume is marked as a template volume, it is
set offline and is read only. A template volume is not intended to be mounted by a host, but instead can be
used to quickly create copies (thin clone volumes) with the same starting data set. For example, in a Virtual
Desktop Infrastructure (VDI) environment a template volume may be used to create a golden boot image for
virtual desktops.
Thin clones can be created from a template volume to use pool space more efficiently. Each thin clone shares
common data in the template volume and only uses additional space to store changes in the volume. Initially,
a thin clone will report the same size and space utilization as the template volume and its contents will be
identical to the template volume. If a host modifies a thin clone, additional space will be allocated up to the
maximum setting for the thin clone volume.
3.8 Volume collections
Dell EqualLogic Group Manager allows for the creation of a collection or a grouping of volumes to allow the
same action to be applied to more than one volume at a time. For example, an administrator may want to
group multiple volumes that contain database and log files for a database server and snapshot them all at the
exact same point in time to maintain consistency across the volumes. In a single operation, simultaneous
snapshots will be taken of all of the volumes that are part of the collection.
Collections may also be used to group volumes for creating replicas. A collection may contain up to eight
volumes from one or more pools, however template volumes are not supported as part of a collection.