HP StorageWorks XP Remote Web Console Software - Manual (Page 201)

TrueCopy for z/OS user guide 201
Load Balancing Control
Current Load Balancing Control
The XP128/XP1024/XP10000/XP12000 has three fixed thresholds and three levels of load balancing for
varying amounts of sidefile cache as follows: Threshold 1/2/3 = 40/50/60%.
• Level 1: Sidefile capacity is 40% -50% of the total cache capacity. Write I/Os are blocked by “Sleep”-
“Wait” logic. The following modes are set on the XP128/XP1024/XP10000/XP12000 SVP:
• Mode 45: “Sleep” -”Wait” suppression option
OFF (Default): Disk array performs “Sleep”-“Wait” command retry per one write I/O to block write
I/O until the amount of sidefile is less than 40% of total cache.
ON: Disk array does not perform “Sleep”-“Wait” command retry.
• Mode 97: “Wait” timer control
OFF (Default): When the amount of sidefile is over 40% of total cache capacity, the
XP128/XP1024/XP10000/XP12000 waits 100 ms as “Sleep”-“Wait” timer for write I/O.
ON: When the amount of sidefile is over 40% of total cache capacity, the
XP128/XP1024/XP10000/XP12000 waits 10 ms as “Sleep”-“Wait” timer for write I/O.
• Level 2: Sidefile capacity is over 50% -60% of the total cache capacity. Write I/Os are blocked by
“SCP”-“SCI” logic. The following modes are set on the XP128/XP1024/XP10000/XP12000 SVP:
• Mode 98: “SCP” reporting suppression option
OFF (Default): When the amount of sidefile is over 50% of total cache capacity, the
XP128/XP1024/XP10000/XP12000 reports SCP status for write I/O. Operating system cannot
issue the write I/O until SCI status is received. The XP128/XP1024/XP10000/XP12000 reports
SCI when the amount of sidefile is less than 50% of the total cache capacity.
ON: The XP128/XP1024/XP10000/XP12000 does not perform “SCP” reporting for write I/O.
• Level 3: Sidefile capacity exceeds 60% in the total cache capacity. Sidefile puncture occurs. The
session that has the largest amount stored in sidefile cache is canceled.
NOTE: The XP128/XP1024/XP10000/XP12000 SVP mode settings are preserved, even during
microprogram exchange or disk array power-off.
Figure 75 Current load balancing control
New Load Balancing Control
The following conditions are required to activate the new DONOTBLOCK option for the XADDPAIR TSO
command: