HP StorageWorks XP Remote Web Console Software - Manual (Page 79)

ShadowImage for Mainframe consistency group, pairs can be deleted. If you delete the
following pairs, the specified split time will be deleted:
◦ Delete all the ShadowImage for Mainframe pairs belonging to the ShadowImage for
Mainframe consistency group.
◦ Delete all the Universal Replicator for Mainframe pairs belonging to the Universal
Replicator for Mainframe restore journal group.
TrueCopy for Mainframe Synchronous (3DC Cascading Configuration)
The XP storage system provides the function to combine Universal Replicator for Mainframe and
TrueCopy for Mainframe Synchronous. This combination is intended to ensure that the secondary
site stores data that has been stored in the primary site even when a failure occurs in the primary
site, regardless of whether the distance between the primary and the secondary sites is short or
long. These intentions will be fulfilled if remote copy operations are performed using cascading
connections and a three data center (3DC) configuration; in a 3DC configuration, an intermediate
site is located between the primary and secondary sites.
The following figure shows an example of a 3DC cascading configuration in which Universal
Replicator for Mainframe and TrueCopy for Mainframe Synchronous are combined. In this
configuration, the volume in the primary site is a TrueCopy for Mainframe Synchronous main
volume (M-VOL). The corresponding TrueCopy for Mainframe Synchronous remote volume
(secondary data volume) is the volume in the intermediate site, which is within a short distance
from the primary site. This TrueCopy for Mainframe Synchronous remote volume is also used as a
Universal Replicator for Mainframe primary data volume. The corresponding Universal Replicator
for Mainframe secondary data volume is the volume in the secondary site, which is within a long
distance from the intermediate site. If a host issues an I/O to the TrueCopy for Mainframe
Synchronous main volume in the primary site, data will be transferred via TrueCopy for Mainframe
Synchronous and Universal Replicator for Mainframe to the secondary site and will be restored to
the secondary data volume.
Figure 32 3DC Cascading Configuration (Combining Universal Replicator for Mainframe with
TrueCopy for Mainframe)
Data that is copied by TrueCopy for Mainframe Synchronous is stored in the Universal Replicator
for Mainframe primary data volume. If a failure occurs at the TrueCopy for Mainframe Synchronous
M-VOL, business tasks can continue by using data in the Universal Replicator for Mainframe
secondary data volume containing data in the TrueCopy for Mainframe Synchronous M-VOL. Data
in the TrueCopy for Mainframe Synchronous M-VOL is restored via Universal Replicator for
Mainframe to the secondary data volume in the secondary site, with update sequence integrity
ensured. If a failure occurs at both the TrueCopy for Mainframe Synchronous M-VOL and secondary
data volume due to a disaster or some other reason, disaster recovery can be performed using the
Universal Replicator for Mainframe secondary data volume.
A TrueCopy for Mainframe Synchronous M-VOL must be created in an XP storage system. The
fence level of the TrueCopy for Mainframe Synchronous M-VOL must be Data (CRIT=Y (ALL)).
The response time for host I/Os is the sum of the response time for TrueCopy for Mainframe
Synchronous operation and the creation time of journal data in an intermediate site.
Interoperability with Other Products and Functions 79