Date: Sat, 1 Oct 2022 14:44:15 -0700 From: David Christensen <dpchrist@holgerdanske.com> To: questions@freebsd.org Subject: Re: data, metadata, backup, and archive integrity and correction Message-ID: <d12b0a89-fc14-4c73-5ef4-ccaf34dad7db@holgerdanske.com> In-Reply-To: <YzhsAw/bUevYmBSX@neutralgood.org> References: <b027f6af-bf83-2663-b0ef-2480e385b189@holgerdanske.com> <c15361a3f8328583bdab528c5a49bf475a1dfdfa.camel@riseup.net> <7be8f47b-bfea-ef5a-7b59-2f94f8d310e2@holgerdanske.com> <ed8431a943b8d3cd74e588c7ee9901c6c166eba8.camel@riseup.net> <166467a7-5aac-6c67-c462-432912c58211@holgerdanske.com> <YzhsAw/bUevYmBSX@neutralgood.org>
index | next in thread | previous in thread | raw e-mail
On 10/1/22 09:34, Kevin P. Neal wrote: > On Fri, Sep 23, 2022 at 06:58:24PM -0700, David Christensen wrote: >> But de-duplication and compression of other data is debatable. >> Photograph files are already compressed; so ZFS compression will be > > Sure, if you use jpeg. If you use TIFF as your intermediate format then > the compression goes away. > > Camera sensors are something like 12 to 14 bits of sensitivity. Using jpeg > throws away that data when you might need it for your editing. TIFF preserves > it because TIFF is 16 bits per channel. > > When you are done and are exporting a picture then jpeg is a good choice. > >> useless. 10 copies of the exact same photograph file should >> de-duplicate nicely. But, open a photograph file in an editor, make >> some changes, save as another file, and repeat 8 more times is likely to >> result in 10 files all with different blocks; so ZFS de-duplication will >> be useless. > > TIFF doesn't suffer from generation loss like jpeg or VHS either. https://en.wikipedia.org/wiki/TIFF#Compression If your TIFF files are uncompressed, then ZFS compression would help. The other two choices appear to use lossless compression (?), so ZFS compression would not help: * CCITT Group 3 1-Dimensional Modified Huffman RLE lossless? * PackBits compression (I do appreciate the advantages of uncompressed, or lossless compressed, photographs, audio, video, etc..) Davidhome | help
Want to link to this message? Use this
URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?d12b0a89-fc14-4c73-5ef4-ccaf34dad7db>