The current snapmirror will finish and then pick up again when the next scheduled transfer is supposed to happen.
So if a source/destination pair is doing a snapmirror update and the current update is not complete before a new update is requested, what is the behavior? Does it queue the second snapmirror update and just update it when the first completes?
I understand the behavior when updates are done by the scheduler on the array itself as per snapmirror.conf. In this case it queues the updates but only to a maximum of three.
"If an update is in progress when another is scheduled to
occur, SnapMirror starts another transfer as soon as the
transfer is complete. However, if three updates pass while
the current transfer is in progress, SnapMirror does only
one more update; it does not go back and run updates
that have been made obsolete by those scheduled later."
But I'm not talking updates initiated by the scheduler on the array itself.
I'm really asking about something like SME performing a backup and requesting an update. The snapmirror update here is functionally equivalent to issuing a snapmirror update command manually. Suppose the mirror does not complete before the next backup and subsequent update request is made (or snapmirror update command issued manually). What if the rate of data change exceeds the ability of network to complete the mirror or if the WAN link to the DR site is just too darn slow? Do the updates queue on the destination and snapshots build up on the source indefinitely? Or do manual or snapmanager initiated updates follow the "queue to three and then give up" rule above?
Anyone know?
Timothy L. Hollingworth
Sr. Network Engineer
ePlus Technology, inc.
511 Davis Drive
Suite 350
Morrisville, NC 27560
678.462.6698 (Direct/Cell)
thollingworth@eplus.com
www.eplus.com
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