Some of you may recall Matt Phelps encountering some trouble with NDMP incremental backups.
We've identified the problem as bug 23356. The bug description will soon be available ONLINE at NOW.
In a nutshell, the problem is this: An NDMP incremental dump will not include files with an mtime which is set to a time BEFORE the timestamp of the last level 0 dump, but created AFTER the timestamp of the last level 0 dump.
Thus, your NDMP incremental backup may be missing some files that were created after the level 0 backup.
The files that will be affected would primarily be: 1) Files that are restored, untar'ed through NFS, CIFS, or the native filer restore or NDMP restore. 2) Files that have has changed permissions, without the actual file changing (we won't back up the changed permissions).
Note that the next level 0 backup WOULD include all of these files.
The history of this bug:
Some customers were encountering problems with various Windows applications using the Win32 API.
Apparently, the ctime of an accessed file is updated by a large number of Windows apps (even if the file is only read) because the apps don't understand "last changed time".
Thus, users with virus scanners would find that their incremental dumps included all files in the system...
So we added a hidden option to NDMP and dump to ignore_ctime. (see online burt 17767 for more details on this issue)
Unfortunately, all incremental NDMP backups incorrectly invoke that option as the default, and it cannot be overridden.
The solution:
We will soon have a 5.3.6 patch available that fixes this problem.
This is also a good time to mention the NOW Bug Watcher utility. When we do a patch release that fixes this bug, those watching the bug will be automatically notified. (I'm guessing it probably works for other bugs, too. ;)
http://now.netapp.com/cgi-bin/relfind?bugs=23356&rels=
And thanks to Matt for being so helpful with this issue.
Stephen Manley NDMP Spokesmodel