HP StorageWorks XP Remote Web Console Software - Manual (Page 16)

16 Continuous Access XP Journal
command is issued on the primary site. The primary disk array transfers data in the journal volume to the
secondary site according to the read journal command if it has journal data that should be sent. If the
primary disk array does not have journal data, the information is sent. The secondary disk array stores the
journal volume data sent from the primary site in the restore journal volume at the secondary site. Read
journal commands are issued repeatedly and regularly from the secondary site to the primary site until the
journal operation is stopped. After data is restored, its journal sequence numbers are returned from the
secondary site to the primary site when the read journal command is issued. Based on this information, the
journal data at the primary site is then discarded.
Journal restore function
This function applies stored data in the restore journal volume to the secondary data volume at the
secondary site. Data in the restore journal volume is restored to the secondary data volume according to
the write sequence number. This ensures write sequence consistency between primary and secondary data
volumes. After journal data is restored to the secondary data volume, journal data is discarded at the
secondary site.
Components
Continuous Access XP Journal operations involve XP10000/XP12000 disk arrays at the primary and
secondary sites, physical communications paths between these disk arrays, and Command View XP or XP
Remote Web Console. Continuous Access XP Journal copies the original online data at the primary site to
backup volumes at the secondary site through dedicated fibre-channel remote copy connections using a
journal volume. You can operate Continuous Access XP Journal with the user-friendly GUI environment
using Command View XP or XP Remote Web Console.
NOTE: Host failover software is required for effective disaster recovery with Continuous Access XP
Journal.
Figure 2 shows Continuous Access XP Journal components and their functions:
Figure 2 Continuous Access XP Journal components