HP StorageWorks XP Remote Web Console Software - Manual (Page 68)

Table 25 Relationship between the Additional Shared Memory and the Number of Usable
Bitmap Areas of Storage System (continued)
Number of Usable Bitmap Areas of Storage System Additional Shared Memory for TrueCopy for Mainframe
16,384 Extension 1
32,768 Extension 2
44,256 Extension 3 (available only for the XP24000 Disk Array)
65,536 Extension 4 (available only for the XP24000 Disk Array)
If the calculated number of bitmap areas exceeds the total number of bitmap areas in the
storage system, the number of pairs that can be created will be limited. Note that the maximum
number of pairs cannot exceed 37,768.
To calculate the maximum number of pairs that you can create:
The maximum number of pairs that you can create
= ( (the total number of bitmap areas in the storage system
Number of bitmap areas) )
The ... symbols around a value indicate that the value should be rounded down to the nearest
whole number.
The maximum number of pairs that you can create cannot exceed 37,768.
The bitmap areas that are used for TC-MF are shared with XP Continuous Access Software,
Universal Replicator for Mainframe, and XP Continuous Access Journal Software. If you use
TC-MF with XP Continuous Access Journal Software, Universal Replicator for Mainframe, and
XP Continuous Access Software, use the total value of both pairs. Also, if TC-MF and Universal
Replicator for Mainframe share the same volume, use the total value of both pairs regardless
of if the shared volume is master or remote.
Performance and DR Considerations
Before starting TrueCopy for Mainframe operations, you must consider the relative importance of
storage system I/O performance and disaster recovery preparation. TrueCopy for Mainframe
operations can affect the I/O performance of the MCUs and RCUs. TrueCopy for Mainframe
provides many options (RCU options, initial copy options, pair options, group options, and async
options) which allow you to control the impact of TrueCopy for Mainframe operations on storage
system I/O performance. These options can be set separately for each TrueCopy for Mainframe
pair, for each TrueCopy for Mainframe Asynchronous group, and for each MCU to provide
maximum flexibility. You can select options which minimize the impact of TrueCopy for Mainframe
operations on storage system performance, or options which maximize the effectiveness of TrueCopy
for Mainframe operations to ensure the best level of backup data integrity. System-level factors (for
example, number of paths) can also affect TrueCopy for Mainframe operations and storage system
performance (
“Optimizing TrueCopy for Mainframe Operations and HP disk array Performance”
(page 139) ).
For TrueCopy for Mainframe disaster recovery operations, you should make sure that the RCUs
are attached to a host processor to enable reporting of sense information and transfer of ERC
information. If the remote site is unattended, you should attach the RCUs to a host processor at the
main site, so that the system administrator can monitor the operational condition of the RCUs.
TrueCopy for Mainframe and ShadowImage for Mainframe can function together in the same HP
disk array to provide both internal and remote backup for your important data. If you are planning
to combine TrueCopy for Mainframe and ShadowImage for Mainframe, read the important
configuration information in
“Interoperability with Other Products and Functions” (page 50) .
68 Preparing for TrueCopy for Mainframe Operations