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From: cmcmanis%pepper@Sun.COM (Chuck McManis)
Newsgroups: comp.sys.amiga
Subject: Re: Comments/Observations of the A2000 || really filesystems
Message-ID: <30504@sun.uucp>
Date: Fri, 9-Oct-87 15:26:37 EDT
Article-I.D.: sun.30504
Posted: Fri Oct  9 15:26:37 1987
Date-Received: Sun, 11-Oct-87 14:38:48 EDT
References: <1188@s.cc.purdue.edu> <1835@gryphon.CTS.COM>
Sender: news@sun.uucp
Reply-To: cmcmanis@sun.UUCP (Chuck McManis)
Organization: Sun Microsystems, Mountain View
Lines: 35

In article <1835@gryphon.CTS.COM> (Richard Sexton) writes:
>I noticed that I had two files with *exactly* the same filename. Odd
>says I, so I try to delete one of them. I didn't care which one :-)
>
>It seemed to delete one of them, but lo and behold the next time I tried
>to get a directory it Guru'd. Curious.

I sent this in as a bug report to C/A back during the Gamma 1 release
but they haven't fixed it yet :-). Basically, if you track down the
GURU number in the alerts.h file you will probably find that the 
number is described as 'corrupt bitmap'. Which you might at first
think means a graphics bitmap, but in fact means the disk bitmap. The
clue is that the address given is the address for the file system handler
task. My contention to C/A was that a corrupt disk should be complained
about but the system should not crash. Anyway the fix is to find the 
error in the disk structure and fix it with disked or some other disk
fixer program. Common errors that cause this problem :
	o Hash pointer pointing to an unititialized diskblock
	o Hash pointer with -1 or some other illegal block number in it
	o Two pointers pointing to the same file.
	
Things you can do with disked that are generally not nice :
	o Put a pointer to a valid amiga file in the *wrong* place in
	  the hash table. Dir shows the file but not one can delete it
	  (or find it for that matter).

	o Make a loop in a hash chain so that once you get that file you
	  loop forever in the directory list. 

These are some of the things that a disk fixer utility has to fix. There
are several available.

--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.