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 SUSE
fsck.ocfs2
fsck.ocfs2(8) OCFS2 Manual Pages fsck.ocfs2(8)
NAME
fsck.ocfs2 - Check an OCFS2 file system.
SYNOPSIS
fsck.ocfs2 [ -fFGnuvVy ] [ -b superblock block ] [ -B block size ] device
DESCRIPTION
fsck.ocfs2 is used to check an OCFS2 file system.
device is the file where the file system is stored (e.g. /dev/sda1). It will almost always be a device file but a regular file will work
as well.
OPTIONS
-b superblock block
Normally, fsck.ocfs2 will read the superblock from the first block of the device. This option specifies an alternate block that the
superblock should be read from. (Use -r instead of this option.)
-B blocksize
The block size, specified in bytes, can range from 512 to 4096. A value of 0, the default, is used to indicate that the blocksize
should be automatically detected.
-D Optimize directories in filesystem. This option causes fsck.ocfs2 to coalesce the directory entries in order to improve the filesys-
tem performance.
-f Force checking even if the file system is clean.
-F By default fsck.ocfs2 will check with the cluster services to ensure that the volume is not in-use (mounted) on any node in the
cluster before proceeding. -F skips this check and should only be used when it can be guaranteed that the volume is not mounted on
any node in the cluster. WARNING: If the cluster check is disabled and the volume is mounted on one or more nodes, file system cor-
ruption is very likely. If unsure, do not use this option.
-G Usually fsck.ocfs2 will silently assume inodes whose generation number does not match the generation number of the super block are
unused inodes. This option causes fsck.ocfs2 to ask the user if these inodes should in fact be marked unused.
-n Give the 'no' answer to all questions that fsck will ask. This guarantees that the file system will not be modified and the device
will be opened read-only. The output of fsck.ocfs2 with this option can be redirected to produce a record of a file system's
faults.
-r backup-number
mkfs.ocfs2 makes upto 6 backup copies of the superblock at offsets 1G, 4G, 16G, 64G, 256G and 1T depending on the size of the vol-
ume. Use this option to specify the backup, 1 thru 6, to use to recover the superblock.
-y Give the 'yes' answer to all questions that fsck will ask. This will repair all faults that fsck.ocfs2 finds but will not give the
operator a chance to intervene if fsck.ocfs2 decides that it wants to drastically repair the file system.
-v This option causes fsck.ocfs2 to produce a very large amount of debugging output.
-V Print version information and exit.
EXIT CODE
The exit code returned by fsck.ocfs2 is the sum of the following conditions:
0 - No errors
1 - File system errors corrected
2 - File system errors corrected, system should
be rebooted
4 - File system errors left uncorrected
8 - Operational error
16 - Usage or syntax error
32 - fsck.ocfs2 canceled by user request
128 - Shared library error
SEE ALSO
mkfs.ocfs2(8) debugfs.ocfs2(8) tunefs.ocfs2(8) mounted.ocfs2(8) ocfs2console(8) o2cb(7)
AUTHORS
Oracle Corporation. This man page entry derives some text, especially the exit code summary, from e2fsck(8) by Theodore Y. Ts'o
<tytso@mit.edu>.
COPYRIGHT
Copyright (C) 2004, 2010 Oracle. All rights reserved.
Version 1.4.3 February 2010 fsck.ocfs2(8)