HP StorageWorks Snapshot XP user guide (T1713-96023, October 2006)

1Overviewofcopysolutions

HP StorageWorks XP12000/XP10000/SVS200 arrays provide an extensive suite of data replication

software. ThischapterdescribesHPStorageWorksSnapshotXP.Thischapteralsocoversportionsof

HP StorageWorks Business Copy XP because Snapshot XP is an integrated feature of Business Copy XP.

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.

IMPORTANT:

This guide contains information about internal disks or L DEVs. Unlike the XP12000/XP10000 Disk

Arrays , the SVS200 has no internal disks. Therefore, information about internal disks or LDEVs does not

apply to the SVS200.

Snapshot XP

Snapshot XP, like Business Copy XP, enables you to create multiple real-time online loc al copies of

logical volumes. Snapshot XP enables applications and solutions such as zero -downtim e 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. It uses less disk space, thus

reducing 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 X P

secondary volumes are partial copies containing only changed P-VOLs. Snapshot XP is also known as

Copy-on-Write Snapshot. Snapshot XP secondary volumes are par tial copies containing only the data

that has been changed in the P-VOLs. Pointers kept in m apping tables allow access to secondary volumes

through virtual volumes (V-VOLs). The S-VOL is composed of data in the pool-VO L (old data that has

since changed in the P-VO L) and data in the P-VOL (data that has not changed yet). The P-VOL/S-VOL

pair that Snapshot XP cre ates is called a Snapshot XP pair.

Figure 1 illustrates the mechanism S napshot XP uses to c opy data in the array.

HP StorageWorks Snapshot XP user guide