Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!mailrus!ames!oliveb!sun!pepper!cmcmanis
From: cmcmanis%pepper@Sun.COM (Chuck McManis)
Newsgroups: comp.sys.amiga
Subject: Re: Fast File System questions
Message-ID: <62264@sun.uucp>
Date: 1 Aug 88 18:01:35 GMT
References: <260@geocub.UUCP>
Sender: news@sun.uucp
Reply-To: cmcmanis@sun.UUCP (Chuck McManis)
Organization: Sun Microsystems, Mountain View
Lines: 41

These questions get asked a lot but they are fairly topical, if someone
has the time to create the "intro" message these should be included for
now, then their 1.4 equivalents should be substituted next year...

In article <260@geocub.UUCP> anthes@geocub.UUCP (Franklin Anthes) writes:
> - is FFS a totally new FS, or just changes made to the old FS?

Yes and no. Yes it is a totally new file system handler, however the 
way the data is stored on the disk is not changed in a really remarkable
way. The only real difference is that datablocks now have 512 bytes of 
data rather than 488. [Yes, that's a "free" 5% increase in space]

> - What changes have been made?

Biggest wins come from sequentially ordered hash chains and full data
blocks. It makes long reads much more appealing (and DMA much more 
efficient). 

> - Why does FFS for diskettes have to wait until 1.4?

Because it won't be in ROM for 1.3, so there is this chicken and egg 
problem where you have a disk and no filesystem in memory yet
that can read it, because the filesystem is on the disk you are trying to
read. See the problem ? Further, some of the stuff that diskettes rely on
(like the ability to deal with being swapped out) is not part of FFS yet.

> - Has something been done to make directory access faster, or will the
>  the speedup in this area just be proportional to the speedup for
>  FFS?

Yes, all aspects of disk activity are faster. My wife (who uses a PC-AT
at work) commented the other day at how fast the directory popped up on 
the screen. Such are the improvements. Anyway, with FFS all hard disk 
activity on the Amiga are faster than equivalent activity on the Mac, PC,
or Atari. 

No I don't know when it will be available. Sorry. 

--Chuck McManis
uucp: {anywhere}!sun!cmcmanis   BIX: cmcmanis  ARPAnet: cmcmanis@sun.com
These opinions are my own and no one elses, but you knew that didn't you.