HP XP7 Storage - Manual (Page 10)

The number of Concurrent Copy (CC) and Compatible XRC sessions for each volume depends on
the combination of CC and XRC (XRC2 and XRC3). The following table shows the number of
sessions for each volume.
Device Emulation Type (3390-1, 3390-2, 3390-3, 3390-9, 3390-A, 3390-L, 3390-M) Session Type
Number of Compatible XRC Sessions Number of CC Sessions
N/A 16 CC only
1 15 CC and XRC2
1 15 CC and XRC3 Single
Reader
1 (Primary session) 15 CC and XRC3
Multiple Reader
0-15 (Auxiliary Sessions)
Performance considerations
Note the following important performance considerations for Compatible XRC operations:
•
Block size. Consider the block sizes when configuring the SC sessions: do not issue too many
write I/Os with large blocks to one SC session.
•
SDM tuning. The performance of Compatible XRC is affected by the performance of SDM.
You must tune SDM to achieve the desired performance. For information on SDM tuning, see
the IBM document Implementing ESS Copy Services on S/390.
Restrictions on usage
Behavior of option settings
The behavior of options set in the Change Option window is affected by the Donot Block
parameter of the XADDPAIR command of SDM. The following table shows the Compatible XRC
options and the behavior of the HP XP7 Storage disk array of the Donot Block parameter of
the XADDPAIR command of SDM.
Behavior of the HP XP7 Storage disk array Compatible XRC Options
"Donot Block" is Not Specified by SDM ("Block" is
Specified) "Donot Block" is Specified by
SDM Setting Option
According to the amount of used sidefile capacity
, the storage system performs the "Sleep" - The storage system does not
control the amount of data to
be written to the specified
volume. Enable Donot Block
(Volume Level)
"Wait" command retry when the threshold
specified by SDM is exceeded.
N/A N/A Disable*
N/A N/A Enable* Level 1 Sleep
According to the amount of used sidefile capacity,
the storage system performs the "Sleep" - The storage system does not
perform the "Sleep" -
"Wait"
command retry.
Disable
"Wait" command retry when the threshold
specified by SDM is exceeded.
The storage system reports an SIM to the host when
the usage of sidefile exceeds the sleep wait
threshold. The storage system does not
report an SIM to the host when
the usage of sidefile exceeds
the sleep wait threshold. Enable Level 1 SIM
10 Requirements and restrictions