HP StorageWorks XP Remote Web Console Software - Manual (Page 53)

If you do not want to reverse the primary data volume and the secondary data volume, you will
be able to cope with a temporary increase in data transfers and a communication path failure
between the primary storage system and the secondary storage system, if the master journal volume
satisfies conditions mentioned earlier. Therefore, the data transfer speed and the volume capacity
required for restore journal volumes are smaller than those required for master journal volumes.
NOTE: The data transfer speed for journal volumes must exceed the data transfer speed in "normal
status."
Contributing Factors for Data Transfer Speed between Storage Systems
The speed of data transfer between the primary storage system and the secondary storage system
depends on the following factors:
•
The bandwidth of data transfer paths
•
The journal transfer speed of the DKC
The data transfer speed between the primary storage system and the secondary storage system
must exceed the data transfer speed in "normal status" mentioned in
Figure 14 (page 53) below.
If a temporary increase in transferred data occurs and the data transfer speed between the primary
storage system and the secondary storage system is exceeded, the excess data will be stored
temporarily in journal volumes.
Figure 14 Data Transfer Speed with URz (Data Transfer Speed between the Primary Storage System
and the Secondary Storage System)
Bandwidth for Data Transfer Paths
The bandwidth (that is, the data transfer speed) of data transfer paths between the primary storage
system and the secondary storage system depends on the user's environment. The bandwidth must
exceed the data transfer speed in "normal status" mentioned earlier.
DKC Journal Transfer Speed
The journal transfer speed of the DKC depends on the number of paths used for transferring journals.
The number of paths for transferring journals must be so enough that the journal transfer speed
exceeds the data transfer speed in the "normal status" mentioned earlier. The maximum number
of paths for each pair of the primary DKC and the secondary DKC is 8.
Planning of Journal Volumes 53