HP StorageWorks XP Remote Web Console Software - Manual (Page 11)

Snapshot XP user guide 11
1 Snapshot XP
Overview
The HP StorageWorks XP10000 and XP12000 disk arrays provide an extensive suite of data replication
software. This chapter describes HP StorageWorks Snapshot XP. This chapter also covers portions of
HP StorageWorks Business Copy XP (BC) because Snapshot XP is an integrated feature of BC.
NOTE: The use of Snapshot XP, Business Copy XP, and all other software products is governed by the
terms of your license agreements with Hewlett-Packard.
Snapshot XP
Snapshot XP, like Business Copy XP, enables you to create multiple real-time online local copies of logical
volumes. Snapshot XP enables applications and solutions such as zero-downtime backup and disaster
recovery. While Business Copy XP creates complete copies, Snapshot XP creates space-efficient copies that
replicate only data from the primary volume that was rewritten using less disk space, which reduces costs.
Snapshot XP is supported on open systems such as UNIX and PC servers. Snapshot XP is an integrated
feature of Business Copy XP.
Snapshot XP creates pairs of primary volumes (P-VOLs) and secondary volumes (S-VOLs). Snapshot XP
secondary volumes are partial copies containing only changed P-VOLs. Snapshot XP is also known as
Copy-on-Write Snapshot. All changed data is kept in common snapshot pools (pool-VOLs). Pointers kept in
mapping tables allow access to secondary volumes through virtual volumes (V-VOLs). The S-VOL is
composed of data in the pool-VOL (old data that has since changed in the P-VOL) and data in the P-VOL
(data that has not changed yet). The P-VOL/S-VOL pair that Snapshot XP creates is called a Snapshot XP
pair.