[Box Backup] Re: Hard Links and rdiff

[Chris Wilson]

Hi John,

On Sat, 12 Apr 2008, John Goerzen wrote:

> Two other questions along these lines.  One is relating to sparse
> files.

I don't believe we treat them as sparse files during backup or restore.

You've certainly managed to find a lot of problems or limitations Box 
Backup very quickly. Well done :-)

>  The other relates to this item in the FAQ:
> 
>   "If a file is modified or replaced by another file with the same
>   modification time, Box Backup will ignore the fact that the file has
>   changed."
> 
> That would imply to me that boxbackup is looking only at mtime when
> determining what needs to be backed up.  In particular, it is likely
> ignoring ctime, inode, and device -- at least one of which should have
> changed in the scenario described.

Yes, it is only using mtime to determine whether files have changed. I've 
been proposing changing this to ctime for a while, mainly confounded by 
the fact that Windows doesn't have ctime at all and therefore this would 
lead to more inconsistency between platforms.

We've also been talking about using an inotify-type interface where 
supported by the OS to detect file changes in real time and avoid the need 
to scan the entire tree, but so far nobody has implemented it.

Cheers, Chris.
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