[OT] Understanding Linux backup limitations

[Bart Silverstrim]

Young wrote:
> Oh, great guru, please hear my plea. :)
> 
> I want to understand why a Linux partition must be unmounted before a 
> cloned image can be created. I haven't been able to find anything yet; I 
> guess I don't know the key word to search.
> 
> I'd appreciate a lead to something that explains this limitation.
> 
> First, I'd like to know if it's a kernel issue, or a file system issue. 
> Then an explanation of why the problem exists.

Part of it is that cloning isn't instantaneous; it takes time, and in 
that time, your files can change, so you get an inconsistent image. Or a 
corrupt one.

Second issue is that not all your filesystem is static; there isn't a 
physical /proc or /dev directory.

Primarily I believe it's the consistency of image problem. You can't 
have a filesystem reliably cloned without locking all files over time or 
having a mechanism in place to verify the state of the files.

I'm sure others will jump in to point out what I'm overlooking :-)

-Bart