Date: Thu, 10 Feb 2005 13:44:34 +0100 From: Pawel Jakub Dawidek <pjd@FreeBSD.org> To: "Loren M. Lang" <lorenl@alzatex.com> Cc: freebsd-geom@freebsd.org Subject: Re: Does geom_uzip act as a variable size storage device? Message-ID: <20050210124434.GB1400@darkness.comp.waw.pl> In-Reply-To: <20050210023919.GC29396@alzatex.com> References: <20050210023919.GC29396@alzatex.com>
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[-- Attachment #1 --] On Wed, Feb 09, 2005 at 06:39:19PM -0800, Loren M. Lang wrote: +> How does the uzip geom work as a block device for a file system. My +> understanding of it is that it operates like a block device that trys to +> compress all data written to it using the same algorithm as used by +> pkzip and gzip. The problem I see with that is that not all data +> compresses by the same amount, some compresses more and other less, so a +> disk that acts as a compressor can hold different amounts of data +> depending on what's written to it. Filesystems like msdos and ufs2 +> don't support running on block devices of variable sizes as far as I know +> so how can I possibly format a uzip disk with a regular filesystem. I +> know that ufs supports being resized, but that's not the same as a block +> device that appears to be constantly changing size as data is being +> written to it so how does uzip work? Does it appear as some fixed size +> that may have wasted space if the data was able to compress really well, +> and when the data doesn't compress well enough, well, I don't know what +> would happen then. +> +> Am I just missing something here or can the uzip geom be dangerous +> depending on how it's used and what fs it's formatted as. You cannot write to geom_uzip's providers. So you need to create provider image (compress your file system) and geom_uzip exports it as read-only provider. -- Pawel Jakub Dawidek http://www.wheel.pl pjd@FreeBSD.org http://www.FreeBSD.org FreeBSD committer Am I Evil? Yes, I Am! [-- Attachment #2 --] -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.4 (FreeBSD) iD8DBQFCC1cyForvXbEpPzQRAurQAKDB1dGRAEi4W72TSi3vhcXtIQtGsQCfReZG f0waQgIhqt7G4TmXJzFbdU4= =ORpp -----END PGP SIGNATURE-----
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