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10.5: Run all Time Machine backups manually System 10.5
Having finally got Time Machine to work on my NAS following the other hints on this site, I came across a big problem. I set up Time Machine on my laptop, which is not always connected to my home network. When out on the road, it would try to sync and fail, which was good. However, when I am out and about, I also use my VPN to connect back to my house. This, I found, would allow Time Machine to back up. At first thought, that sounds good ... but doing so when connecting via 3G really doesn't work well.

So I changed the configuration of Time Machine such that it would not automatically backup, but rather do it when I tell it to do so. Go to System preferences » Time Machine, and make sure 'Show Time Machine status in the menu bar' is checked, then turn off Time Machine.

Now in the menu bar at the top of the screen, click the Time Machine icon and select Back Up Now when you want to back up. This finally allows me to back up when I'm on my home network, and not at other times unless I really want to. Of course, this also puts the onus back onto me to remember to run the backup frequently.

[robg adds: The interesting tidbit here (to me, at least) is that Time Machine will run even when it's been set to "off." I'm also interested to see if others have different methods of making sure a machine only backs up when desired -- are there solutions that still allow automatic backup when at home, and manual backup when not directly on the home network?]
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10.5: Run all Time Machine backups manually | 9 comments | Create New Account
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Be careful with Time Machine and non-Apple NAS storage...
Authored by: dbs on Jan 26, '09 08:02:12AM

Be careful with this setup. The disk image used for the backup may become corrupted if it is not unmounted cleanly on a third-party fileserver. (E.g., anytime the network is interrupted or the machine is put to sleep during a backup you can end up with journal data not being flushed to the disk image, which may corrupt it. I've heard that this is why Apple does not support backups to third party disks that don't support the changes to file sharing in 10.5.)

If you want to use a third party NAS, the only reasonably safe way to do it is to backup to an Apple-supported machine, and then copy that data (e.g., via rsync) to the NAS when no backups are occurring.



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Be careful with Time Machine and non-Apple NAS storage...
Authored by: rjbailey on Jan 26, '09 08:16:17AM
This is all true, but it doesn't have anything to do with this hint. The hint merely disables the automatic initiation of Time Machine backups. The remote sparsebundle is mounted and dismounted by the OS just as it otherwise would be.
I've been using this method for a couple of months now without a problem. In fact my frequency of corruption of the sparsebundle image on the server has decreased, because I can begin backups when I know there is less chance of server interruption. And also simply because the number of backups is lower. (Do I really need 24 backups each day? Others, maybe. Me, no.)

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Be careful with Time Machine and non-Apple NAS storage...
Authored by: dbs on Jan 30, '09 07:18:06PM

You're right that this doesn't have anything to do with the above hint (except to say that the setup described is dangerous), but you're probably not right that it works just the same.

Although I don't know for certain that this is the only reason third-party file servers aren't supported, I can explain why this is almost certainly dangerous: For any file system to have a reliable disk journal (which is what tries to prevent filesystem corruption), it needs to guarantee that the journal is in a known state before any other operations occur. If you're using a disk image over a network, this would mean that you have to guarantee that all journal-related transactions are physically written to the remote disk before other operations are executed. (E.g., not stored in a cache, memory, or a network switch.) Since the NAS just sees multiple writes to a file (the disk image) it will happily cache it (problematic if the power goes out), wait for the network connection to close before writing it (problematic if the network is flaky), or even re-order them for performance (defeats the atomicity requirement of the journal). I'm guessing that Apple doesn't support third-party NAS systems because no third-party SMB or AFP servers support this capability as far as I know, and if they did, Apple would have to have to verify it was supported, and have a way to use it.

I'm sure someone with more understanding of filesystems and journaling (or HFS+ in particular) could give a more detailed description, but that's the general gist of it.

Either way, if you actually care about your backup (and that's kind of the point of a backup) it would be very foolish to trust it to something that is explicitly not supported. I was personally quite disappointed that this isn't supported since I had bought a mirrored NAS for precisely this purpose. So what I do is to backup over a wired network to a time capsule (supported config) and then do an rsync to a NAS in another physical location. This gets around the journal issue by only copying the data when the disk is in a known state: e.g., unmounted. I verify filesystem before each copy, and haven't had a problem yet even with hourly backups from two computers.



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Time Machine Scheduler
Authored by: gshenaut on Jan 26, '09 08:16:30AM
turns time machine "off" and allows you to schedule when you would like to have it run. I use it to get just one backup per day (at night) because hourly backups were clobbering my system & wifi latency.

http://www.klieme.com/TimeMachineScheduler.html

donationware

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Time Machine Editor
Authored by: nschum on Jan 27, '09 01:25:05AM
There is also Time Machine Editor, which has slightly different options.

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10.5: Run all Time Machine backups manually
Authored by: neuralstatic on Jan 26, '09 09:42:59AM

in regards to turning it off and on:

maybe 'do something when' or a similar app can toggle it off or on depending on subnet or wifi name. i haven't used it for a while but it seemed very configurable for this type of thing.



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10.5: Run all Time Machine backups manually
Authored by: maq1017 on Jan 26, '09 12:40:18PM

Intrigued by this hint...

In order for your machine to locate your TM backup across then VPN, wouldn't this have to be located via Bonjour???

If so, I'd be very interested to know how you got Bonjour working across a VPN as all broadcast packets get lost as far as I can figure out, and this is something I'd love to achieve.

Great tip too



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10.5: Run all Time Machine backups manually
Authored by: hamarkus on Jan 26, '09 01:29:04PM

I've managed to get access to TM on my TC simply by mounting it via its IP address. At some point it stopped working, maybe my ISP started to block some ports. After having it mounted once, TM even automatically mounted it on its own. It was scary and cool at the same time. The scary part was that AFP connections (how I mounted the TC) are not encrypted, ie, I was backing up my HD unencrypted over the internet, which was another reason why I did not investigate it further (after it stopped working).



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10.5: Run all Time Machine backups manually
Authored by: NedScott on Jan 28, '09 04:10:28AM

How can anyone not know how to do this? It is a well documented feature, to boot.



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