Release Notes

6 Dell PS Series Snapshots and Clones: Best Practices and Sizing Guidelines | BP1027
1 Introduction
The lab validated best practices in this paper will help IT and SAN administrators understand and fully utilize
the powerful snapshot and clone features delivered with every PS Series array.
This paper describes:
• The differences between snapshots and clones and where each can be used for data protection and
recovery
• How to properly and efficiently size snapshot reserve space
• How to invoke a snapshot or clone a volume
• How to restore from a snapshot or clone of a volume
• Performance implications when using snapshots and clones
• Best practices for using snapshots and clones
The results presented in this paper will help determine specific needs for any SAN environment.
1.1 Audience
This white paper is for storage administrators who are involved in the planning, implementation, configuration,
and administration of PS Series iSCSI storage area networks and the use of snapshots and clones for the
purpose of data recovery and availability.
1.2 Terminology
The following terms are used throughout this document.
Base volume: A volume that a snapshot initially shares data with or a clone volume is copied.
Block: A unit of data access specified during an input/output (I/O) operation.
Clone: A full copy of a volume.
Collection: A logical grouping of 1-8 volumes that allows the same operation (such as a snapshot or clone
replica) to be performed on all volumes in the collection simultaneously.
Page: A logical grouping of data segments within a PS Series volume, snapshot, clone volume or replica.
Pool: A collection of storage space comprising of one or more members. Volumes are then created from free
space within an available pool.
Replica: A point-in-time copy of a volume placed on another PS Series array group using auto replication.
Snapshot: The storage feature that preserves the contents of a volume at a point in time.
Template volume: A volume that is designated as read only and then used as a source for creating thin
clones
Thin clone: A space efficient copy of a template volume that only stores its unique changes.