When MVS™ detects a loss of
connectivity, MVS determines
the viability of rebuilding each structure affected by the connectivity
loss.
If MVS determines that there
is an active SFM policy in the sysplex:
- MVS verifies that the SFM
policy data is at the same level on all systems.
- MVS checks the active CFRM
policy to see if a rebuild percent value has been specified for affected
structures, or takes the default rebuild percent value of 1.
- MVS calculates
the total system weight of (A) all systems containing at least one
active connection to the structure in the coupling facility to which
connectivity has been lost, and (B) all systems having at least one
active connection to the structure. Note that if there are multiple
users of a structure on one system, that system weight is counted
only once.
For example, if a structure has one connection per system
and all systems are of equal weight 10, then in an eight-system sysplex
if one system lost connectivity the value of A (total system weight
of all systems containing an active connection that have lost connectivity)
is 10 and the value of B (total system weight of all systems containing
an active connection) is 80.
- MVS determines what action
is to be taken and informs the connected users through event exit
processing.
The determination is arrived at by dividing A by B,
multiplying by 100, and then comparing the result with the rebuild
percent for the structure in the CFRM policy.
- If the result is greater than or equal to REBUILDPERCENT, then MVS initiates a user-managedrebuild.
- If the result is less than REBUILDPERCENT, MVS does not initiate a rebuild.
In this example, (10/80)*100 would be the value compared
to the REBUILDPERCENT value. If the value of REBUILDPERCENT was 13
or higher, a rebuild would not be initiated.
If MVS determines
that there is not an active SFM policy in the sysplex, MVS initiates user-managed rebuild
for loss of connectivity to a structure, regardless of the REBUILDPERCENT
specification.