Suspend Types - HP StorageWorks P9000 User Manual

where:
◦ C is total capacity (MB) of the master journal volume.
u is the usage rate of data (%) in the master journal volume.
◦
V is data transfer speed (MB/sec) between the primary and the secondary systems.
◦
See "Usage Monitor window " (page 184)
volume.
The Continuous Access Journal Z SEQCHK status is indicated when a Continuous Access
Journal Z pair assigned to a mirror with the System timer type accepts a non time stamped
update from the primary system. The SEQCHK status does not affect Continuous Access Journal
Z copy activities and is removed when the next time stamped update is successfully copied
to the S-VOL. However, if a disaster or system failure occurs before the next time stamped
update, the update sequence consistency between the S-VOL and other S-VOLs in the mirror
is not ensured. To ensure effective disaster recovery, you should detect and remove the source
of the SEQCHK status. The SEQCHK status can be caused by any of the following.
An application may issue update I/Os bypassing the MVS standard I/O procedure.
◦
The I/O time stamping function may not be active at the primary site.
◦
When the status of the Cnt Ac-J Z pair status is Pending, neither cache nor shared memory
can be added to or removed from the storage system. Before adding or removing the cache
or shared memory, check the pair status and split pairs whose status is Pending; then,
resynchronize the pair when the memory operation completes.

Suspend types

You can suspend a pair after the initial copy operation is complete. When you suspend a pair,
the primary and secondary systems insure synchronization by completing or discarding any pending
update copy operations. This depends on the Suspend Mode option that you specify in the Suspend
Pair operation.
A pair can also be suspended by the primary or secondary storage system. System suspensions
occur for the following conditions:
When the primary system detects that the user has released the volume pair from the secondary
storage system
When the primary system detects an error condition related to the secondary system, S-VOL,
or a journal data operation
When the secondary system cannot execute DFW (DASD fast write (DFW)) to the S-VOL (if
DFW is specified)
When the primary system is unable to communicate with the secondary system
When a pair is suspended, the primary system stops updating the S-VOL. The primary and secondary
systems keep track of journal data discarded during suspension. Also, the primary system continues
accepting write I/Os for the P-VOL and keeps track of the P-VOL tracks which are updated while
the pair is suspended.
In addition to the Suspended status, an S-VOL also has a consistency status, which indicates its
update sequential consistency with respect to the other S-VOLs in the same group. The consistency
status is available only on the secondary system. See
suspended S-VOL consistency statuses.
When a pair is suspended, the primary system generates sense information to notify the host(s).
Table 12 (page 84) provides suspension types and descriptions.
for instructions on viewing the usage rate of a journal
Table 13 (page 85) for descriptions of
Monitor pair activity, status 83