Path: utzoo!attcan!utgpu!news-server.csri.toronto.edu!rutgers!cs.utexas.edu!wuarchive!udel!mmdf
From: archer%segin4.segin.fr@relay.prime.com (Vincent Archer)
Newsgroups: comp.os.minix
Subject: Re: fix to diskcheck(1)
Message-ID: <31308@nigel.ee.udel.edu>
Date: 23 Sep 90 16:23:37 GMT
Sender: mmdf@ee.udel.edu
Lines: 21

Of course, i should have tought of it. Reading from /dev/mem (or rather
/dev/kmem) would be very nice. /dev/null is out of question, you CAN'T read
anything from it. In fact, it would be exactly as it is now, reading from
/dev/ram (which is empty).

To answer another question, why do we read NR_BUFS instead of just doing a sync
That's for emptying the buffer cache of FS, that's why. sync does the writing,
not the reading. That's needed because diskcheck verifies that what was written
can be read back. But if the sector is still in the cache, you will ALWAYS read
back what you wrote... because it won't be read, it will be taken from the disk
cache!

The real thing is to solve the cache matter once for all. Use the raw device,
which bypass the cache entirely.

_________
 |\___/|	Vincent Archer
 | \ / |	Email: archer%segin4.segin.fr@relay.prime.com
 | /|\ |
 |// \\|
-+-----+-	"Time is running fast..."