HP StorageWorks XP24000/XP20000 for Compatible Extended Remote Copy (XRC) Software User's Guide (T5238-96001, March 2008)

Note: When the DKC emulation type is 3990-6 or 3990-6E, only the XRC2 function is supported.
When the DKC emulation type is 2105 or 2107, XRC2 or XRC3 is supported.
Number of Sessions
Table 4 on page 23 shows the number of sessions in Compatible XRC.
Table 4 Number of HP Compatible XRC Sessions
Number of SessionsUnit
Number of CUs × 64Per disk storage system
64Per CU
1Per volume
The number of Concurrent Copy (CC) and XRC sessions per volume depends on the combination of
CC and XRC (XRC2 and XRC3). The number of sessions per volume is shown in Table 5 on page 23.
Table 5 Number of Sessions per Volume
DKU Emulation TypeSession Type
3390-1, 3390-2, 3390-3, 3390-3R, 3390-9, 3390-L, 3390-M
Number of HP Compatible XRC
Sessions
Number of CC Sessions
—16CC only
115CC and XRC2
115CC and XRC3
Performance Considerations
Please note the following when performing XRC operations.
• HP recommends that you have one ESCON path for one SC session.
• Take the block sizes into consideration when configuring the SC sessions (do not issue too many
write I/Os with large blocks to one SC session).
The performance of XRC is affected by the performance of SDM. Please tune the SDM in order to
achieve the desired performance. For SDM tuning, please refer to RedBook's Implementing ESS Copy
Services on S/390 published by IBM, or contact IBM.
Notes and Questions
This section provides several tables of system information useful when performing HP Compatible XRC
operations. This section also provides some additional considerations to be observed regarding
Compatible XRC.
• Additional cache requirement
XP24000/XP20000 for Compatible Extended Remote Copy (XRC) Software User's Guide 23