Time Machine reconnect old sparsebundle

Question

I encountered a problem with a corrupt sparsebundle (I use TimeMachine with my Synology NAS) and Time Machine creating a new sparsebundle, not using the my good old sparsebundle with all my previous backups.
Maybe there are people with the same problem, so here is my solution.
First I had to repair my original sparsebundle image (in this post, the filename is further called A ). TimeMachine seems to rename this sparsebundle giving it read-only rights. To bypass that: ssh with Terminal to your NAS and navigate to the folder which you pointed out as backup folder for Synology Mac Backup.
type:
+chmod 1777 A+
End your SSH session with the NAS, but keep Terminal open. Open 'Finder' and navigate to the backupfolder on your NAS (so the folder is mounted). Then, go back to Terminal and go to /Volumes/*backup folder*/. If you type ' +ls -ls+ ' in your Terminal, the sparsebundle will be shown.
Then to mount and repair, type:
+hdiutil attach -nomount -readwrite A+
then a list with disks appear as output. Remember the bottom one (with me /dev/disk1s2).
type:
+fsck_hfs -rf remembered_path+
This can take a while (like 12 hours or so, depending on the size of your sparsebundle).
Sometimes this process quits with an error (with me it did), but restarting the process worked for me (so just type in the command again).
Then, manually start a Time Machine Backup (letting it create a new sparsebundle). Wait until the 'Making backup disk available' disappears and stop the backup. Disable TimeMachine again.
Go to Terminal again and ssh to your NAS.
Go to the folder again with the sparsebundles.
Type ' +ls -ls+ ', remember the name of the sparsebundle created last, i call this X.
type:
+cd X+
type:
+cp Info.plist ../A+
+cp Info.bckup ../A+
+cp com.apple.TimeMachine.MachineID.plist ../A+
+cd ..+
+mv X choosea_filename_not_ending_withsparsebundle+
+mv A to X+
If you point Time Machine to use the NAS disk again, the backup process will go and continue to backup to your good 'ol sparsebundle.
For me it worked, hope it does for others!!
Message was edited by: edstasy

Answer 1

edstasy wrote:
Pondini wrote:
The file system +directories and catalogs+ may be ok, but that doesn't mean your backups are complete.
I have used a lot of information from this page: http://blog.jthon.com/?p=31
It seems that this issue is common when backing up over WiFi (see comment reply by Phil, #10).
The original post, and most of the replies, are from 2008 (Leopard). The "verification" process wasn't added until mid-May of 2010. They may or may not be addressing the same thing.
Also, there is nothing wrong with the disk in the NAS, there probably was a process which was not ended correctly that corrupted the image.
Yes, that's one of the possibilities. Since Apple hasn't provided a glimmer of a clue as to what's actually wrong, there's no telling.
As long as you realize you may be backing-up to damaged or incomplete backups, that's certainly your call.
I cannot guarantee that the backup will work (no one can). I just reconnected the sparsebundle, now Time Machine is happy again and I am happy again
Of course, I could prove this fix by restoring from Time Machine, but I'm not going into that now, maybe I will test that later on.
That would be prudent. But restore to an empty disk/partition, so if it fails, you're not in a bigger pickle. You might try it twice; once from the last backup before the message, once from a later one.