Notice On System Operation - Hitachi VSP F1500 User And Reference Manual

• Repeats above until detecting an EOM(End Of Marker) marked on all RCU
via RCU
• Issues End of Delete to terminate a deleting state

Notice on system operation

CCI does not change the command options for supporting Universal
Replicator MxN Open. However, the output of the command is added so that
the command can display the consistency group and Q-Marker for each
storage system, because the consistency group and Q-Marker are managed
on each storage system.
(1) Consistency group ID and journal ID for UR
The consistency group ID must be assigned/used as the unique identifier
across multiple storage systems. Therefore, the paircreate command makes a
group volume having the same consistency group ID across multiple storage
systems.
(2) Cascading operation
The "-FHORC" option for cascading operation does not perform with CTQ-
Marker Mode. Hence the cascading volume must not be specified UR MxN
volume when using the "-FHORC" option.
(3) Running HORCM daemon
HORCM daemon process delivers the timestamps (called the consistency Q-
Marker) to the defined consistency group. Therefore if HORCM daemon is
stopped, then UR will stop to delta (commit) and will suspend because of
Journal Full state.
Thus HORCM daemon must be running to keep the PAIR state.
(4) Separating a command device IO from application IO
The HORCM daemon process issues IOs to the command device in order to
deliver the timestamps to the defined consistency group. Therefore, it is
recommended to separate the command device path from the application IO
path.
(5) About waiting application IO
The HORCM daemon process delivers the timestamps to the defined
consistency group while freezing IO for each journal.
Waiting Rate = 0.5ms * Number of journal / / Interval (ms) * 100
(Note that 0.5 ms depends on the OS platform.)
Therefore it is recommended to limit within four journal per consistency
group and 8192 LDEVs per consistency group. In the case of multiple
6-50
Data replication operations with CCI
Command Control Interface User and Reference Guide