Re: File system compression, not at the block layer

[Jörn Engel]

On Tue, 27 April 2004 18:00:11 -0700, David Lang wrote:
> 
> to answer the fundamental question that was asked in this thread but not
> answered.
> 
> the reason why we want to compress at the block level instead of over the
> entire file is that sometimes we want to do random seeks into the middle
> of the file or replace a chunk in the middle of a file (edits, inserts,
> etc). by doing the compression in a block the worst that you have to do is
> to read that one block, decompress it and get your data out (or modify the
> block, compress it and put it back on disk). if your unit of compression
> is the entire file each of these options will require manipulating basicly
> the entire file (Ok, reads you can possibly stop after you found your
> data)

*IF* your unit of compression...

If that is the complete block device, you're stupid and deserve what
you get.  If it is the file, same thing.  No difference.

Do it at the file system level or don't do it at all.

Jörn

-- 
Don't worry about people stealing your ideas. If your ideas are any good,
you'll have to ram them down people's throats.
-- Howard Aiken quoted by Ken Iverson quoted by Jim Horning quoted by
   Raph Levien, 1979
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