Why is Time Machine not able to backup network drives.

[Phonzel]

I don't own a Mac yet but will buy a Air in a few weeks.
I'm already thinking about storage and backup strategies. Because I've got a lot of big files and the Air rather not that much memory, I'm forced to use an external drive. I don't like cables so it'll be a network drive.

As a backup solution, Time Machine (or even a Time Capsule) seems to be perfect. But of course I want to backup my network drive too, without a second backup software.
Now, this seems to be impossible with TM? But why?

 

[old-wiz]

I think it's due to the amount of traffic it would put on the network plus trying to keep track of what's modified. A networked drive can be accessed and modified without the Mac knowing about it so time machine would have a difficult time keeping track. When the drive is attached to the Mac, file system/TM can keep track of file modifications.

 

[Phonzel]

Ok, makes sense, but as far as I know you can backup external drives (USB..) with Time Machine. What happens if those will be changed using another PC?
I'm pretty sure TM can handle that!

And regarding network traffic: Of course it's more, but usually your backup storage is a network device as well, so this problem shuldn't be to serious.

Maybe this is just the first case of 'Apple knows it better' for me..

 

[prisstratton]

Ok, makes sense, but as far as I know you can backup external drives (USB..) with Time Machine. What happens if those will be changed using another PC?
I'm pretty sure TM can handle that!

And regarding network traffic: Of course it's more, but usually your backup storage is a network device as well, so this problem shuldn't be to serious.

Maybe this is just the first case of 'Apple knows it better' for me..

Maybe give this site a read, it is full of very good information regarding how Time Machine works:

http://pondini.org/TM/2.html

 

[Phonzel]

http://pondini.org/TM/2.html

Thanks, really informative!

Answers on Apples Support Community are like "it's not possible because it is not a feature".

So I'm still not satisfied..

Edit: Got a satisfying answer: https://discussions.apple.com/message/22700061

 

[velocityg4]

I would add that for a good network drive it is not necessary to have a computer to perform it's backup routines. It should have the ability to backup to another drive on the network and/or a drive connected directly to it. Many can even backup over the internet.

 

[Bear]

Ok, makes sense, but as far as I know you can backup external drives (USB..) with Time Machine. What happens if those will be changed using another PC?
I'm pretty sure TM can handle that!
...

You can only backup HFS+ formatted drives with Time Machine. External USB (or FIreWire or Thunderbolt) connected drives (HFS+ format of course) work fine with Time Machine.