HP XP for Compatible Extended Remote Copy Software Licenses - Manual (Page 13)

2 About Compatible XRC Operations
This chapter contains details and examples of the data replication process.
• Function Overview
• Configuration
• Interoperability with Other Products and Functions
Function Overview
In HP Compatible XRC operations, the data written from the primary host at the primary site is written
to the primary volume by means of the cache memory at the primary storage system. At the same
time, the data is temporarily stored in cache memory as a sidefile. At the secondary site, System Data
Mover (SDM)—which is host software—asynchronously reads the sidefile data over communication
lines from the primary storage system at the primary site. SDM then writes the data to the secondary
volume in the secondary storage system in the same order as it was written at the primary site.
SDM manages pair definitions of the primary and secondary storage systems or pair definitions of
the primary and secondary volumes. An overview of XRC operations is shown in
Figure 1 on page 13.
Figure 1 Overview of HP Compatible XRC Operations
Sessions
In HP Compatible XRC operations, a group of primary volumes is processed as one session. Data is
written to the secondary volumes in each session in the same order as it was written at the primary
site. In the event of a failure, all volume pairs in the same session are suspended. The write operation
XP24000/XP20000 for Compatible Extended Remote Copy (XRC) Software User's Guide 13