The XRC volume pair initialization function selects the next volume
to synchronize or resynchronize, and prioritizes the volumes from
the command's list of volumes. The first priority is to resynchronize
existing volume pairs, then to add new volume pairs to the XRC session.
XRC selects and adds new pairs as needed according to the PRIORITY
subparameter (FIFO or LOAD), which you can specify with the XSET command.
See Table 1 for more information.
Table 1. PRIORITY specification with the XADDPAIR command| If you specify . . . |
Then . . . |
Notes . . . |
|---|
| PRIORITY(FIFO) |
XRC processes the volumes that were
listed by an XADDPAIR command in the order that they are listed. |
- First, XRC processes all volumes that are eligible for resynchronization.
- Next, XRC processes all volumes that are eligible for synchronization.
XRC processes the volumes within the limits that you specified in
the SYNCH and SCSYNCH parameters of the XSET command.
|
| PRIORITY(LOAD) |
XRC processes the volumes that were
listed by an XADDPAIR command based on the primary and secondary storage
control load in this order: |
- First, XRC processes all volumes that are eligible for resynchronization.
XRC can defer the initialization if the associated storage control
has too much activity at the time that the volume is eligible. The
volume continues to be eligible for processing when the activity level
has decreased.
- Next, XRC processes all volumes that are eligible for synchronization.
Again, XRC can defer the initialization if the primary storage control
activity is too high. XRC performs both resynchronization and synchronization
processing within the limits that the SYNCH and SCSYNCH parameters
of the XEND command specify.
|