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Table 8 sidefile thresholds, Graduated delay sidefile management, 8 sidefile thresholds – HP StorageWorks XP Remote Web Console Software User Manual

Page 32: Table 8

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32

Hitachi TrueCopy z/OS for HP XP12000/XP10000 and SVS 200 storage systems

• Inflow control by RCU: If the RCU is not able to settle a recordset within the user-specified offloading

timer value, the RCU suspends all TC390A volume pairs and resets the channel-command-retry

condition to avoid hanging up the MCU.

HXRC. HXRC operations use a different cache sidefile than TC390A.

Table 8

on page 32 also shows the

sidefile threshold values for HXRC operations and describes the actions that occur when each threshold is

reached. Disk arrays performing TC390A in combination with HXRC must have sufficient cache installed to

handle the increased sidefile activity. If a “sidefile puncture” condition occurs (HXRC sidefiles reach 10%

over threshold), the XRC session having the highest sidefile usage is terminated.
SIM reporting for sidefile conditions is disabled when mode 118 is OFF (

Table 3

on page 18).

NOTE:

Cache LUN XP operations may decrease the total amount of cache available for TC390A and

HXRC operations, but do not directly affect sidefile cache usage. Available cache is defined as the amount

of physical cache memory installed on the disk array minus any cache reserved for the Cache LUN XP

feature.

Graduated delay sidefile management

The following figure shows the graduated delay process for TC390A sidefile management. When the

TC390A sidefile value reaches the high-water mark (threshold minus 20%), the XP12000/XP10000 begins

command retry delay for host updates to TC390A M-VOLs and reports a warning SIM to the host. As the

amount of sidefile increases, the delay increases incrementally as shown in the following figure. Use Mode

93 on the XP12000/XP10000 SVP (see

Table 3

on page 18) to select the delay type (long or short). This

graduated delay methodology minimizes the potential for sidefile overcommitment, while at the same time

providing another level of automation control.

Table 8

Sidefile thresholds

Operation

Threshold(s)

Action(s)

TC390A

High-water mark (HWM) = sidefile threshold –

20%

MCU (RCU) reaches HWM: command

retry to host (MCU), begin graduated

delay. Delay times can be adjusted using

mode 93 (see

Table 3

on page 18).

Sidefile threshold = 30-70% of cache, default =

50%.
TC390A threshold can be adjusted from 30-70%

(in 10% increments) using TC390 through XP

Command View Advanced Edition Software or XP

Remote Web Console.

MCU (RCU) reaches threshold: command

retry to host (MCU), max delay time (500

or 100 ms). Delay time can be adjusted

using mode 93 (see

Table 3

on page 18).

Puncture threshold = sidefile threshold + 10%

MCU (RCU) reaches puncture: suspend

affected TC390A pairs due to sidefile

overflow condition.

HXRC

1

1. For more information on sidefile thresholds for HXRC operations, see ”

HXRC device blocking and load balancing

” on

page 216.

[XRC sidefile] / [avail cache] = 40%, 50%, 60%
XRC thresholds can be adjusted by using modes 85

and 86 (see

Table 3

on page 18).

Threshold 1/2/3 = 30/40/50%, 40/50/60%, or

60/70/80%

Threshold 1 = command retry.
Threshold 2 = SCP message.
Threshold 3 = puncture condition.

Write Pending

[write pending] / [avail cache - sidefile] = 70%

Command retry.

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