- session_id
- Specifies the name of an XRC session. This can be any name that
was previously specified on an XSTART command, except for the word
ALL. The maximum length of the name is eight characters. Do not include
embedded blanks. TSO ignores leading blanks and trailing blanks.
- TIMEOUT
- Specifies the minimum time that a storage control can wait
for the XRC session to restart and begin to offload records from the
primary storage controls. If you do not restart the XRC session within
the time that you specified with the TIMEOUT variable, the primary
storage controls take action to recover cache resources that are associated
with the storage control session. Storage controls that do not support
hardware bitmapping end their XRC sessions
at the end of the specified TIMEOUT duration. Storage controls that
support hardware bitmapping suspend their
XRC sessions and perform hardware bitmapping of changes to primary
volumes.
The TIMEOUT parameter allows you to control the impact
that a suspension operation has on the application program. The minimum
TIMEOUT value is one second (00.00.01); the maximum TIMEOUT value
is 18 hours (18.00.00).
The TIMEOUT timeframe begins when update
activity causes storage control cache to exceed a threshold value.
If an IEA482I message is received, application updates remain stopped
until the "busy-control-unit" condition is relieved. If the storage
control ends the storage control session, you must restart the storage
control session and fully synchronize all volumes in the session.
When
you specify TIMEOUT, XRC suspends the entire XRC session, and ends
the ANTASnnn system data mover address space.
The TIMEOUT parameter is mutually exclusive with the VOLUME parameter.
When
you issue the XSUSPEND command with the TIMEOUT(STORAGE_CONTROL_DEFAULT)
parameter, XRC uses the default that is set in the storage control.
This value is normally five minutes (00.05.00).
Note: - If all of the storage subsystems in your environment support the
hardware bitmap function, you can set a low timeout value; the hardware
bitmap ensures a rapid resynchronization time. If some or none of
the storage subsystems in your environment support the hardware bitmap
function, set the timeout limit to minimize the effect on applications.
Take into consideration how long a full-volume resynchronization will
take for storage subsystems without hardware bitmapping.
- ESS storage subsystems suspend their sessions as a part of XSUSPEND
processing. Therefore, the TIMEOUT parameter does not affect these
subsystems.
- The XSUSPEND TIMEOUT parameter specifies the acceptable application
impact (expected duration) for a planned outage. For comparison, the
XSET TIMEOUT parameter specifies the acceptable application impact
for normal SDM operations.
- VOLUME
- Specifies the volume serial numbers of the primary volumes that
XRC is to suspend from the session. When XRC suspends a volume, the
SDM continues to read record updates from the primary storage control.
The SDM does not apply updates to the secondary volume while the volume
remains in a suspended state. You may specify up to 100 primary volume
serial numbers on a command. Use either a blank or a comma to separate
each primary volume serial number.
The XSUSPEND command will fail
if you include a utility volume in the volume list. You can add or
delete utility volumes, but you cannot suspend them.
Note: Although you cannot explicitly suspend a utility volume,
XRC can internally suspend a utility volume if all of the data volumes
in the storage control session are suspended by command or due to
an error. When Enhanced Multi-Reader is in effect, all utility volumes
in the Enhanced Multi-Reader group for that storage control session
are suspended.
When
you specify XSUSPEND VOLUME(ALL), XRC suspends all volume pairs and
all utility volumes in the session. The ANTASnnn address
space remains active. The system data mover continues to read record
updates for storage controls that do not support a hardware bitmap.
The
VOLUME parameter is mutually exclusive with the TIMEOUT parameter.
For additional information about the potential impact on the application
program, refer to Suspending an XRC session.