From: Brandon S. Allbery (bsa@kf8nh.wariat.org)
Date: 04/14/93 

From: bsa@kf8nh.wariat.org (Brandon S. Allbery)
Subject: Re: New feature for the filesystems. What do you think ?
Date: Wed, 14 Apr 1993 12:23:56 GMT

In article <1993Apr13.200801.24748@serval.net.wsu.edu> hlu@eecs.wsu.edu (HJ Lu) writes:
>In article <C5Fp7K.r9o@watson.ibm.com>, rajat@watson.ibm.com (Rajat Datta) writes:
>|> Why not just build a compressed filesystem? That is, compress all the
>|> blocks, metadata and all. With MSDOS 6.0 coming with builtin
>
>I am wondering how a compressed filesystem handles demand paging and
>random update.

The "proper" way to do a compressed filesystem is in fact not a compressed
*filesystem* at all, it's a compressed *disk*. Which means that individual
blocks are compressed regardless of contents. Since *ix does updates on
entire blocks in all (current) cases, this imposes only a decompression speed
penalty on demand paging.

Of course, it *does* make it rather difficult to put an FFS on a compressed
drive, since you need to sandwich an uncompress/recompress operation around
fragment updates....

++Brandon 

-- 
Brandon S. Allbery                                       bsa@kf8nh.wariat.org

It's not too late to turn back from the "Gates" of Hell...
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