HP StorageWorks XP Remote Web Console Software - Manual (Page 46)

secondary data volume (if the path status is normal) to suspended. When a pair is suspended from the
secondary storage system, the secondary storage system changes the status of the secondary data
volume to suspended, and the primary storage system detects the pair suspension (if the path status is
normal) and changes the primary data volume status to suspended. When you release a pair from the
primary storage system, the primary storage system changes the status of the primary data volume and
secondary data volume (if the path status is normal) to simplex. When you release a pair from the
secondary storage system, the secondary storage system changes the secondary data volume status
to simplex, and the primary storage system detects the pair release (if the path status is normal) and
changes the primary data volume status to suspended.
When a URz data volume pair is split or suspended, the primary storage system generates a service
information message (SIM) to notify the host(s). If SNMP is installed and operational for XP disk array,
this SIM results in an SNMP trap which indicates the reason for suspension.
• URz Pair Status
The URz Suspending and Deleting (release) transitional states occur when a request to change URz
pair status has been accepted, but the change to the requested status (suspended, or simplex) is not
yet complete. These states are not reported to the host. In the case of Suspending, both the user and
the primary storage system can request the status change. In the case of Deleting (release), only the
user can request the status change. If the user requested the status change, the final status is reported
at the end of the transition. If an error caused the status to change to suspended, the suspended status
is reported at the beginning of the transition.
After a storage system receives a request for splitting or releasing a pair in Flush mode, the status of
the pair will remain Suspending or Deleting until the journal in the master journal group is restored
into the restore journal group and the pair is completely split or released. To calculate the time during
which the pair remains Suspending or Deleting, use the following equation:
C × (u ч 100) Ч 1,024 ч V (The unit is seconds)
where:
• C is the total capacity of the master journal volume. The unit is megabytes.
• u is the usage rate of data in the master journal volume. The unit is percent.
• V is the data transfer speed between the primary and the secondary storage system. The unit
is MB/s (megabytes per second).
To find the usage rate of a journal volume, use the monitoring feature (see
“ Usage Monitor Window ” on page 171).
The URz SEQCHK status is indicated when a URz pair assigned to a consistency group with the
System timer type accepts a non-time-stamped update from the primary system. The SEQCHK status
does not affect URz copy activities and will be removed when the next time-stamped update is
successfully copied to the secondary data volume. However, if a disaster or system failure occurs
before the next time-stamped update, the update sequence consistency between the secondary data
volume and other secondary data volumes in the consistency group 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.
• This URz pair status describes:
• URz suspend types (see the next section),
• URz suspension condition (see “
Suspension Condition ” on page 50).
46 Overview of Universal Replicator Operations