Re: announce: ext2 compression patch

Miquel van Smoorenburg (miquels@drinkel.ow.org)
Sat, 23 Mar 1996 20:29:18 +0100 (MET)

In article <9603221627.AA20799@gnu.mc.xerox.com>,
Marty Leisner <leisner@sdsp.mc.xerox.com> wrote:
>
>I have to agree with Jerry Pournelle on this (he had a column a few
>months ago in Byte where he talked about this).
>
>On the fly compression to writable file systems is a bad idea...
>It encrypts your whole file system making recovery impossible...

It should be implemented differently; compression should be
in a file-basis, not on a device-basis. This way, if a bit or
byte falls over on your disk, it will just cause one (part of a)
file to get corrupted.

For example, use a file system with 8K blocks. The file system
should use 1K blocks internally. Compress every 8K block independently,
and store the compressed 8K blocks in several 1K blocks.

I splitted bash in 8K blocks, and gzipped -9 every 8K block.
The total nr. of blocks was 128, while the normal bash is 221 blocks.
It's not to bad; gzip -9 on bash itself creates a bash.gz of 106
blocks.

Mike.

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