05-11-2014
You don't state what hardware platform you have, what the cluster software suite is, or what the backup software is.
Your post indicates that you have a good understanding of how a (generically speaking) cluster works and that any one filesystem can only be under the control of one node at a time. Having multiple nodes thinking they could write to the volume would be anarchy and a clear recipe for data corruption. It is definitely the job of the cluster software suite to ensure that that never happens. Having said that, different cluster suites can have starkly different functionality.
Similarly, backup software suites also vary in the manner of operation.
So discussing cluster backup in generic terms I would say that there are two options for implementing backups. Firstly, when node-A fails and node-B takes over (by checking orphaned filesystems and then mounting them, taking over and broadcasting the cluster name and ip address (node-C and ipaddr-C) some cluster software will also failover scheduled jobs (eg, backup). Of course, the backup device(s) need to be still available (or node-B needs to have its own tape drive, for example) for this to work. Alternatively, like all the user community who only know about node-C and ipaddr-C, the backup is run from a machine outside the cluster which "calls in" on node-C, accesses or NFS mounts the filesystem, and backs it up. Usually, this is the preferred method.
Now in this scenario the backup software has no knowledge that it is backing up a cluster volume and it should work exactly the same way as it would with a local volume, ie, if it loses communication with the volume, it will report a backup failure. Some backup software suites (eg, NetBackup) are of client/server architecture which are very intelligent and will report failures in exactly the same way they usually do.
So in summary, the fact that it is a cluster should be largely irrelevant to reporting errors in backup schedules. How the success of a backup is verified is the same as the non-cluster scenario.
Hope that helps. Feel free to continue your questions but please give us all a clue of the platform and software(s) involved.
Last edited by hicksd8; 05-11-2014 at 12:46 PM..
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LEARN ABOUT DEBIAN
votequorum_leaving
VOTEQUORUM_LEAVING(3) Corosync Cluster Engine Programmer's Manual VOTEQUORUM_LEAVING(3)
NAME
votequorum_leaving - Tell other nodes that we are leaving the cluster
SYNOPSIS
#include <corosync/votequorum.h>
int votequorum_leaving(votequorum_handle_t handle);
DESCRIPTION
The votequorum_leaving function is used to tell the other nodes in the cluster that this node is leaving. They will (when the node actually
leaves) reduce quorum to keep the cluster running without this node.
This function should only be called if it is known that the node is being shut down for a known reason and could be out of the cluster for
an extended period of time.
Normal behaviour is for the cluster to reduce the total number of votes, but NOT expected_votes when a node leave the cluster, so the clus-
ter could become inquorate. This is correct behaviour and is ther eto prevent split-brain.
Do NOT call this function unless you know what you are doing.
RETURN VALUE
This call returns the CS_OK value if successful, otherwise an error is returned.
ERRORS
The errors are undocumented.
SEE ALSO
votequorum_overview(8), votequorum_initialize(3), votequorum_finalize(3), votequorum_dispatch(3), votequorum_fd_get(3),
corosync Man Page 2009-01-26 VOTEQUORUM_LEAVING(3)