This is a filesystem problem rather than a backup problem. I'm not
*specifically* trying to make excuses for NetWorker here, but it bases its
incremental backup on the timestamp of the file. If the timestamp is more
recent than the previous backup, it will back up the file.
Some filesystems update the "last modified" time on renames, some don't.
However, there is no reasonable way for the software to check every file on an
incremental backup without using the modification time. The directories are
changed and get backed up, but the files inside those directories are unchanged
according to the filesystem, don't get backed up, and therefore don't hit the
NetWorker indexes. My guess is that the directory tree is created each time
within the indexes in order to ensure that the data comes back "as it was", to
the exclusion of any files which were deleted between the full and incremental
and therefore cannot be referenced via the filesystem during backup to show the
deletion. This means that your map1 directory no longer exists, files within
map1a are unchanged since the last backup, and map3 and file5 have been created
and are backed up accordingly. Even a journalled filesystem will not get
around this, as the remainder of the files are not modified.
The only good solution to this problem at this time is to always do full
backups, or change to a filesystem where this doesn't happen (and I don't have
a list). Instructing users to copy and delete rather than rename directories
isn't a realistic answer to this, neither is to update all filesystems to
report every file being changed when a directory is renamed. It's not an easy
one to fix. Probably best is simply to ask users to check for any renamed
directories after you restore a directory tree for them.
Cheers,
Stuart.
________________________________
From: EMC NetWorker discussion on behalf of Voetelink D.
Sent: Fri 29-Sep-06 10:04
To: NETWORKER AT LISTSERV.TEMPLE DOT EDU
Subject: [Networker] Recovering renamed directories
Hi,
Last week we needed to do a recovery of an entire drive of a windows
system, because microsoft's SMS had wiped it clean.
So we started networker user, selected the drive and started to recover.
For this it needed a full and a couple of incrementals.
After the recover was complete some users complained that not all files
were there. With the 'change browsetime' option we were able to recover
the files/directories.
The problem seems to be in directories which have been renamed/moved in
the period between the full and the last incremental.
to reproduce:
See the following structure:
E:\
map1\
file1.txt
file2.txt
map2\
file3.txt
file4.txt
Now do a full backup of E:
- Now rename map1 to map1a
- Create a new file 'file5.txt' in map1a
- Create a new directory 'map3' and move 'map2' to 'map3'
This means the structure has become:
E:\
map1a\
file1.txt
file2.txt
file5.txt
map3\
map2\
file3.txt
file4.txt
Now do an incremental backup of E:
Now start the 'networker user', choose 'recover' and choose E:.
You'll see map1a and map3. This was the situation of the last
incremental backup, so far so good.
However if you select map1a, you'll notice that only file5.txt is
visible and selectable. file1.txt and file2.txt are not selectable.
Also map3 is without content, buth map2 should be in there.
the command line tool 'recover' has the exact same problem. I tried
different versions of client and server software, all with the same
problem.
Also Linux clients seem to have the exact same problem.
This way it's impossible to do a reliable restore of the last situation,
because there are files missing!
And there I was, thinking the purpose of backup software was to be able
to do a reliable recovery. What was I thinking?!? ;-)
Any thoughts anyone?
greetings,
Dennis
--
*******************************************************************
D. Voetelink
UNIX Systems Administrator
Energy research Centre of the Netherlands
Facilities Department - Automation Services
Petten, Netherlands
e-mail : voetelink AT ecn DOT nl
phone : (+31) 224 564738
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