Visible Impact of Transient State Events

Table 8-1 summarizes the user-visible impact of transient state events from the viewpoint of a shadow set on one system on an OpenVMS Cluster system. For each type of transient state event, the effects on the shadow set, when a merge (full merge, HBMM, or controller minimerge) or copy (full or minicopy) operation is already underway, are listed. The terms Canceled, Restarted, Continued, and Suspended, have the same meaning in this table as in Volume Shadowing for OpenVMS messages:

Canceled — Operation is stopped so that it can be restarted or continued on any system that is eligible.
Restarted — Operation must start over again on the same system at LBN 0 when the operation is resumed.
Continued — Operation continues at the LBN where it left off when canceled or suspended.
Suspended — Operation is stopped such that the operation for that SS can be initiated, restarted, or continued only on the same system where the suspended operation is active.

The following are the characteristics of merge and copy operations:

If both a merge and a copy are pending on a shadow set, the merge is done before the copy if and only if the merge is a minimerge. This applies to controller-based minimerges, host-based minimerges, full copies, and minicopies.
If an event that specifies a delay occurs during the delay for some earlier event, no additional delay is incurred. The merges or copies required for the current event are considered when the earlier delay expires.
If an event that specifies no delay occurs during the delay for some earlier event, the merges or copies required for the “no-delay” event are not considered until the earlier delay expires.

Table 8-1 Visible Impact of Transient State Events

Event^[1]	Shadow Set (SS) Focus	New work required	What happens prior to merge /copy on SS?				Delay^[2]
			Prior full merge or HBMM	Prior controller minimerge	Prior full copy	Prior minicopy
Failure of other system that had at least one mounted SS in common with this system.	All SSs that were mounted on failed system.	Merge required.	Canceled and is restarted.	If on failed system, it restarts. Otherwise, minimerge continues with added work.	Canceled but is eventually continued.	Canceled but is eventually continued. Continued as full copy if minicopy master bitmap was on failed system.	Yes
	All other SSs with prior merge or copy state.	No new work.	Canceled but is continued.	No change.	Canceled but is continued.	Canceled but is continued.	Yes

Failure of a system that did not have any SS mounted in common with this system.	All other SSs with prior merge or copy state.	No new work.	No change.	No change.	No change.	No Change.	Yes

SS aborted on another system, with writes in restart queue on the aborting system; SS is also mounted on this system.	Aborted SS.	Merge required.	Canceled and is restarted.	If on failed system, it restarts. Otherwise, minimerge continues with added work.	Canceled but is continued.	Canceled but is continued.	Yes
	All other SSs with prior merge or copy state.	No new work.	Canceled but is continued.	No change.	Canceled but is continued.	Canceled but is continued.	Yes

Other system dismounts a SS that has a merge or copy in progress on its system; SS is also mounted on this system.	SS dismounted on other system.	No new work.	Continued.	Restarted.	Continued.	Continued.	No
	All other SSs with prior merge or copy state.	No change.	No change.	No change.	No change.	No change.	No

A member is added to a SS that is mounted on this system.	Specified SS.	Copy required.	Canceled but is continued.	No change.	No change.	No change.	No
	All other SSs with prior merge or copy state.	No new work.	No change.	No change.	No change.	No change.	No

Mount a SS that requires a merge or copy; SS is not mounted on any other system.	Specified SS.	Copy and/or merge required.	Restarted as full merge.	Restarted as full merge.	Restarted.	Restarted as full copy.	No

SET SHADOW /DEMAND_MERGE command issued on any system for SS mounted on this system.	Specified SS does not use controller minimerge.	Merge required.	Restarted.	Not applicable.	Canceled but is continued.	Canceled but is continued.	No
	Specified SS uses controller minimerge.	Full merge required.	Restarted	Suspended and restarted as full merge.	Canceled but is continued.	Canceled but is continued.	No
	All other SSs with prior merge or copy state.	No change.	No change.	No change.	No change.	No change.	No

SET SHADOW /EVAL=RESOURCES command issued on this system.	All SSs mounted on this system with prior merge or copy state.	No change.	Canceled but is continued.	No change.	Canceled but is continued.	Canceled but is continued.	Yes
^[1]Each event is described from the perspective of one system in a cluster. ^[2]Delay represents a predetermined length of time that elapses before the operation begins. It is the total of the values specified for the SHADOW_REC_DLY and RECNXINTERVAL system parameters.