Date: Mon, 10 Aug 2009 19:08:35 -0800 From: Mel Flynn <mel.flynn+fbsd.questions@mailing.thruhere.net> To: freebsd-questions@freebsd.org Cc: Roland Smith <rsmith@xs4all.nl>, Jay Hall <jhall@socket.net> Subject: Re: Backup Size Message-ID: <200908101908.36042.mel.flynn%2Bfbsd.questions@mailing.thruhere.net> In-Reply-To: <D0D2566C-8912-4F77-BB54-714C7DB4B2D2@socket.net> References: <6206A242-7226-48E3-8D09-A1D3A651F2A8@socket.net> <20090810170921.GC49364@slackbox.xs4all.nl> <D0D2566C-8912-4F77-BB54-714C7DB4B2D2@socket.net>
next in thread | previous in thread | raw e-mail | index | archive | help
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
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?200908101908.36042.mel.flynn%2Bfbsd.questions>