HP StorageWorks XP Remote Web Console Software - Manual (Page 94)

Master
JNLVOL
Restore
JNLVOL
Primary
site
URz
secondary site
Sec. data
VOL
S-VOL
JNLVOL
TCz Synchronous
(short distance)
URz
(long distance)
(for use as an alternative)
TCz Synchronous
secondary site
P-VOL: primary volume
S-VOL: secondary volume
Prm. data VOL: primary data volume
Sec. data VOL secondary data volume
P-VOL/Prm.
data VOL
URz
(long distance)
JNLVOL: journal volume
Figure 37 3DC Multi-target Configuration (Combining URz with TCz Synchronous)
In this configuration, the primary volume in the primary site is paired with the secondary volume for TCz
Synchronous. This primary volume is also paired with the secondary volume for URz. If a host in the
primary site writes data to the primary volume, the data will be written to the TCz Synchronous secondary
volume in real time, synchronously with writing from the host. The data will also be written to the URz
secondary data volume, asynchronously with writing from the host. Update sequence consistency will be
maintained with the URz secondary data volume.
Since writing from the URz primary volume to the URz secondary volume is performed asynchronously
with writing from the host to the primary volume, this configuration can prevent delay in response to the
host even if the URz primary site and the URz secondary site are far from each other.
In addition, you can create the URz pair for delta resync operation in 3DC multi-target configuration,
by specifying TCz Synchronous R-VOL in the TCz Synchronous secondary site as the URz primary data
volume, and by specifying the volume in the URz secondary site as the URz secondary data volume. If
you create the URz pair for delta resync operation, you can resynchronize the URz pair by using journal
data in the TCz Synchronous secondary site when a failure occurs in the primary site.
For detailed information about the hardware configuration required for 3DC multi-target
configuration, see “ Hardware Configuration ” on page 94. For detailed informa­
tion about the requirements to create a URz pair for delta resync operation, see
“ Requirements for Creating URz Pair for Delta Resync Operation ” on page 96. As for the requirements to
perform delta resync operation, see “ Requirements for Performing Delta Resync Operation ” on page 96.
If a failure occurs in a TCz Synchronous primary volume, which is also used as a URz
primary data volume, you can resume business tasks by using the TCz Synchronous secondary
volume. After you resume business tasks, you need to remove the failure from the primary
volume and transfer business tasks back to the primary site. For details, see sections
“ Recovering from Failures in the Primary Site and the TCz Synchronous Secondary Site ” on page 104
through “ Transferring Business Tasks from the URz Secondary Site to the Primary Site ” on page 105.
If a failure occurs in both the primary volume and the TCz Synchronous secondary volume, you can
resume your business tasks by using the URz secondary data volume. After you resume business tasks,
you need to remove the failure from the primary volume and the TCz Synchronous secondary volume, and
transfer business tasks back to the primary site.
Hardware Configuration
A computer system in 3DC multi-target configuration requires the following three sites:
• Primary site for both TCz Synchronous and URz
• Secondary site for TCz Synchronous
• Secondary site for URz
94 Preparing for Universal Replicator z/OS Operations