Path: utzoo!attcan!uunet!samsung!gem.mps.ohio-state.edu!apple!mattd
From: mattd@Apple.COM (Matt Deatherage)
Newsgroups: comp.sys.apple
Subject: Re: Directory trashed by GS/OS.  HELP!!!
Message-ID: <36691@apple.Apple.COM>
Date: 21 Nov 89 18:53:02 GMT
References: <8911202203.AA06213@apple.com> <3955@crdgw1.crd.ge.com>
Organization: Apple Computer Inc, Cupertino, CA
Lines: 65

In article <3955@crdgw1.crd.ge.com> rankins@zaire.crd.ge.com (raymond r rankins) writes:
>
>Well, one of the directories
>I want to copy off causes Cat.Doctor to return:
>
>			MLI error: $4A - Incompatible file type
>
>when I try to do anything on the directory.  What does this mean?
>Can this be fixed with Block Warden, or could someone tell me how to at
>least get a list of what's in the directory?  (it's a bunch of files that
>I just downloaded from America Online, so I could always download them again
>if I could remember what all of them were).  
>
Glen's error message has caused more confusion that necessary.  The error
means incompatible STORAGE type.  It means you're trying to delete a file with
more than one fork (an extended file) from ProDOS 8, which doesn't know
how to do that.  P8 only knows how certain kinds of files (seedling, sapling,
tree, directory) are "constructed" on disk, and it politely refuses to deal
with other kinds of files to prevent it from doing something stupid.

>I think I'll get rid of the
>ram cache (800k) I have set in GSOS because I've heard that a disk can
>get trashed if the system fails and a disk update is in progress in the
>ram cache.  
>
ACK!  ACK!  ACK!

It is true that if the disk cache is corrupted while a "session" is in progress,
things could get in serious trouble.  However, unless you have a misbehaving
DA or INIT, this isn't too likely.

However, 800K is *way too much* memory to be spending on a disk cache.  Under
normal circumstances, directory blocks are all that's in the cache anyway
(it's not wise to blindly cache everything you read, see GS/OS Technical Note
#3 for more details).  GS/OS is smart enough not to allocate 800K, only as 
needed, but a 32K or 64K maximum cache size should keep most systems flowing
smoothly.

>Also, why can Prodos 8 read my disk (except for the bad dirs), but GSOS won't
>read it at all?
>
The ProDOS file system has a lot of checks, balances and cross-checks to insure
data (and directory) integrity.  Backwards links, forwards links, version
numbers (now no longer there), etc.  ProDOS 8 has never used most of them, but
the ProDOS FST does.  If the FST finds these things messed up, it returns
error $51 and/or displays "Volume /XXX may be damaged."  ProDOS 8, which doesn't
check, will happily use the disk anyway, perhaps causing creeping errors
because something isn't quite right.

BTW, you can use ProSEL 16's utilities to deal with these things from GS/OS -
it will copy extended files.

>Ray Rankins          |  (518) 387-7340  | INTERNET: rankins@zaire.crd.ge.com
>2 Moonglow Rd.       |  (518) 583-3320  | COMPUSERVE: 71131,3236
>Gansevoort, NY 12831 |                  | AmericaOnline: RayRankins

-- 
-----------------------------------------------------------------------------
Matt Deatherage, Apple Computer, Inc. | "The opinions expressed in this tome
Send PERSONAL mail ONLY (please) to:  | should not be construed to imply that
Amer. Online: Matt DTS                | Apple Computer, Inc., or any of its
ThisNet: mattd@apple.com              | subsidiaries, in whole or in part,
ThatNet: (stuff)!ames!apple!mattd     | have any opinion on any subject."
Other mail by request only, please.   | "So there."
-----------------------------------------------------------------------------