TimeMachine breaks after reboot / scrub

[oracle_sod]

I have the TimeMachine functionality active, and it works as expected, my mac backs up when it wants to and i can log in and restore files

however, if i ever reboot the device or after doing a scrub of the volume i start to get a message on my mac that it has to complete a full backup again and i lose all the past backups..

im not sure whats causing this, are there any logs i should look on on either device ?
anyone know how to resolve this ?

 

[gpsguy]

Try a Google search on the forum, for example: site:forums.freenas.org time machine problems

Here's the result from the first entry in the search results - time-machine-keeps-restarting-backup-job

ps. I don't know anything about Mac's ;-)

 

[oracle_sod]

already did that... and i did come across the link you shared.... although it doesn't apply to my situation...

My backup works day to day, i can restore and it does the incremental backups successfully, however its when my FreeNAS is rebooted or a scrub job is automatically run that it breaks and has to run a full backup again because something changes that the mac can see after either of those events...

 

[oracle_sod]

So i found a fix... but still no real answer on the actual cause....

the fix is http://www.garth.org/archives/2011,...ine-sparsebundle-nas-based-backup-errors.html

I would still like to know what actually changes on the sparse bundle to cause the time machine software on OSX to detect it as corrupted...

any ideas ?

 

[cyberjock]

Never used a Mac, but it sounds like time machine keeps certain files open all the time when your Mac is running. If you reboot the server with those files open then Time Machine ends up being unable to figure out what is going on because those files weren't properly closed before the server rebooted.

You could test this easily. Next time you want to reboot your FreeNAS server shutdown your Macs. Then reboot FreeNAS. After FreeNAS is booted up completely boot your Macs up and see what Time Machine says.

 

[JaimieV]

Time Machine doesn't act like that, CJ - no files are held open, and the TM target is completely dismounted by the client between the hourly backup sessions.

 

[fracai]

I'm running two Macs (laptop and desktop) that backup via TimeMachine hosted on FreeNAS. The only "restarting" problem that I've seen is on the laptop. And I suspect that this occurs when the backup is interrupted for some reason. Two possibilities come to mind: a drop in network connectivity or the laptop sleeping while the backup is in progress (inactivity while unplugged or being closed). There isn't much I can do about the network dropping out (I'm not sure this actually happens all that much), but I've disabled backups when on battery and I try to be diligent about not closing while the backup is running.

So, basically what I think is going on is that TM starts backing up, but is interrupted and uncleanly dismounts the backup target. When starting the next time, TM scans the backup or notices that it did not finish cleanly and marks the target for starting over.

Overall, my solution for recovering from this state is to enable snapshots on the TimeMachine files and then rollback to whatever the most recent snapshot is that occurs after a successful TM backup. Much faster than repairing the image.

 

[JaimieV]

I've not seen any restarting behaviour here. Well, not restarting from scratch: if you shut the lid on a Mac laptop while it's writing to its TM destination, it'll tidy up, dismount the TM archive and then go to sleep. On the next opportunity, it'll pick up from where it left off.

Reboots and scrubs of the NAS (a low-end HP N36L) make no difference, without taking any care about doing it when the Macs aren't actively backing up. Scrubs never should anyway.

It's fairly rare for the TM backups to get corrupted. I've got four Macs running hourly TM's (when they're awake, anyway) and I've had one corrupted backup in the last year or so. And that's with running beta OS versions, and unsupported TM destinations (like FreeNAS). I double-target my TMs, so I just deleted the corrupt backup and copied over the good one - but the snapshots idea would have been far quicker, I'm doing that next time, thanks!

Back to the issue:
A reboot while busy, ok I can see that. But if a *scrub* operation is causing things to break, perhaps the hardware is on edge or woefully underspecced. Whatcha got, oracle_sod?