Hitachi TrueCopy for IBM z/OS User and Reference Guide (T5211-96001, June 2007)

Performing TrueCopy for z/OS Pair Operations 6-21
Hitachi Universal Storage Platform V TrueCopy for IBM z/OS User’s Guide
• SSB [F/M=FB]: When this option is enabled (and PPRC Support = Yes), the
MCU will notify all attached hosts (IEA494I message) that the pair was
suspended. This option should always be enabled. Note: If PPRC support =
No, the x’FB’ sense information will not be reported to the host, even if the
SSB (F/M = FB) suspend option is enabled.
• Suspend Kind (default = R-VOL):
– R-VOL: the M-VOL will accept all subsequent write I/O operations, and
the MCU will keep track of updates while the pair is suspended.
Subsequent write I/O operations to the M-VOL will be accepted or rejected
depending on the fence level of the pair. This setting is available from the
MCU and RCU, and should be used if you need to keep the M-VOL online.
All TrueCopy for z/OS Async pairs have this setting. This setting is
functionally equivalent to CSUSPEND with the optional PRIMARY
parameter (without QUIESCE).
– M-VOL Failure (available only for TrueCopy for z/OS Sync and only when
connected to the MCU): the MCU will reject all write I/O operations to the
M-VOL while the pair is suspended, regardless of the M-VOL fence level
setting. This setting should be used if you need to maintain
synchronization of the TCz pair. This setting is functionally equivalent to
CSUSPEND without the optional PRIMARY parameter.
• Asynchronous Parameters:
– Suspend Range: Group or Volume (default = Group when one pair is
selected, default = Volume when two or more pairs are selected). The
CSUSPEND TSO command supports the TCzA suspend range option.
Group: The MCU/RCU will suspend all other pairs in the same
consistency group as the selected pair. This option is available only
when one pair is selected.
Volume: The MCU/RCU will suspend only the specified pair(s) (even if
the error level of the pair is group). Note: For the Volume suspend
range setting, if you select pairs with duplex status and other than
duplex status in the same consistency group, unexpected suspend may
occur during the pair operations (suspend, resynchronize, release)
under heavy I/O load conditions. You can estimate whether the I/O load
is heavy or not from the rate of sidefile cache (around 30%), or if you
cannot see the sidefile cache rate, from the frequency of host I/O. The
suspend pair operations should be performed under light I/O load
conditions.
– Pending Update: Drain or Purge (default = Drain). The CSUSPEND TSO
command supports the TCzA pending update suspend option.
Drain: As soon as the RCU accepts the Suspend Pair operation, the
RCU will finish settling all pending recordsets for the pair. After settling
all pending recordsets, if there are no recordsets for a fixed period of
time, the MCU will change the pair status from Suspending to
Suspended.