Backup Size
Mel Flynn
mel.flynn+fbsd.questions at mailing.thruhere.net
Tue Aug 11 03:08:39 UTC 2009
On Monday 10 August 2009 18:24:19 Jay Hall wrote:
> On Aug 10, 2009, at 12:09 PM, Roland Smith wrote:
> >> The fact that you are using tar also plays a part. Tar has some
> >> overhead to
> >> store information about the files it contains.
>
> Is it possible to calculate the amount of overhead tar will use?
Difficult. 512 bytes per entry + 1024 (EOF). See man 5 tar. But since files
will be padded there is some extra overhead. Also, it is hard to calculate
hard links and sparse files. Tar will handle these correctly (i.e. preserve
hard links and detect sparse files and try not archive "blocks of nulls") but
it is hard to calculate the size because of this before the archive operation
because of this.
--
Mel
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