Re: definiing deduplication

["Thomas Schmitt" <scdbackup@gmx.net>]

Hi,

i wrote:
> > Data of different files or at different places in the same file
> > may have relations which may become inconsistent during change operations
> > until the overall change is complete.

Stefan Monnier wrote:
> Arguably this can be considered as a bug in the application (because
> a failure in the middle could thus result in an inconsistent state).

A backup programmer or operator does not necessarily have influence on
such applications.


> if you don't use snapshots, [...] the bug is in the backup
> process itself.

The backuper is not to blame if the backupee filesystem cannot make
snapshots, and anyways snapshots don't completely solve the consistency
problem of backups.

That's another reason why i propose to divide the backupee into several
subsets which separate agile parts from lazy parts.
The backup of agile data possibly needs special precautions like shutting
down or pausing particular applications.

Having multiple backups of the same backupee reduces the risk to have
no consistent copy when the backup needs to be restored.


Have a nice day :)

Thomas