HP StorageWorks XP Remote Web Console Software - Manual (Page 75)

reported to the primary site, and then the fact that I/O has been finished will be reported to the
host. Also, data in the URz primary data volume (that is, TCz Synchronous R-VOL) will be stored
as journal data into the master journal volume in the intermediate site. Sequence numbers, which
indicates the order that data will be written, will be added to these journal data. Also, journal data
in the master journal volume in the intermediate site will be transferred, independently from and
asynchronously with the behavior mentioned above, to the restore journal volume in the secondary
site. Next, the journal data in the restore journal volume will be restored to the URz secondary
data volume in the secondary site; the journal data will be restored in the order of sequence
numbers that are added to journal data. These sequence numbers ensure that updates to URz
secondary data volumes in the secondary site will be made in the same order that updates to TCz
Synchronous M-VOL in the primary site are made.
As explained above, when the host in the primary site issues an I/O request to the TCz Synchronous
M-VOL, the data will be restored asynchronously to the URz secondary data volume in the secondary
site in a remote location.
Figure 36 Basic Behavior in 3DC Cascading Configuration
If a TCz Synchronous pair is suspended in a 3DC cascading configuration, you will be able to
resynchronize the pair by using differential copy. If a URz pair is suspended, you will be able to
resynchronize the pair by using differential copy.
NOTE: To perform disaster recovery from a failure in the primary site in a 3DC cascading
configuration, you must ensure that the fence level of the TCz Synchronous M-VOL is Data (CRIT=Y
(ALL))). If this fence level is specified, you can perform disaster recovery by using the URz secondary
data volume that contains the data stored in the TCz Synchronous M-VOL.
Hardware Configuration
This section explains hardware configuration for a 3DC cascading configuration using TCz
Synchronous and UR-z/OS. In a 3DC cascading configuration, three XP storage systems are
required. It is recommended that Business Continuity Manager is installed on hosts in the primary
site, the intermediate site, and the secondary site. XP Remote Web Console computers are required
for these sites. The following list explains hardware configuration for these sites.
•
Primary site
The XP storage system must have TCz Synchronous installed. ◦
◦ The XP storage system must have TCz Synchronous M-VOL.
◦ Storage system settings must be made so that Business Continuity Manager can be used.
For detailed information about settings required for using volumes in a remote site, see
HP StorageWorks XP for Business Continuity Manager Software User's Guide.
•
Intermediate site
The XP storage system must have TCz Synchronous installed. ◦
◦ The XP storage system must have URz installed.
◦ The XP storage system must have a volume used as both a TCz Synchronous R-VOL and
a URz primary data volume.
Combining URz with Other Data Management Operations 75