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From: wrp@biochsn.acc.Virginia.EDU (William R. Pearson)
Newsgroups: comp.sys.mips
Subject: bad block tables lost?
Message-ID: <1991May15.010630.24949@murdoch.acc.Virginia.EDU>
Date: 15 May 91 01:06:30 GMT
Sender: usenet@murdoch.acc.Virginia.EDU
Organization: University of Virginia
Lines: 33


	The 300 Mbyte system drive on my MIPS M/120 died today - there
seemed to be a bad sector in the swap partition (fortunately I have a
service contract and should get a new one tomorrow).  What surprised
me was my inability to recover from the problem by reformatting the
disk and scanning for bad blocks.  When I reformatted with the format.std
program from 4.52 distribution tape, no problems were encountered.
Scanning likewise did not uncover any bad blocks.  When I listed the bad
blocks, none were found.

	I was surprised when my customer support person told me that I
should not have tried to list the bad block table, because, according to
him, a bug in the software causes the table to be erased after it is
listed, and it must be reentered manually.  Is this true?  Is this fact
mentioned somewhere in the volumes of release notes that I am constantly
refered to?  Is there any version of RISC/os that allows one to format a
disk and examine/edit the bad-block table without destroying it?

	This seems like a very serious bug to me. It is also insidious,
since it tends to require that I keep my machine under maintenance
with MIPS, since it is now very difficult to reformat a disk with a
few bad blocks; the disk almost must be returned to the factory and
exchanged for a known good one.  On other computers, I have found that
disks may loose a sector now and then, often because of bad power
fluctuations, but they can then be reformatted, scanned, and put back
in use in an hour or so. By not allowing the bad-block table to be
examined and modified, a simple reformat becomes a disk exchange.

	Earlier, I installed a third-party disk after formatting without
any problems under RISC/os 4.01(2?).  Did its format/scan/list-bad-blocks
function better?

Bill Pearson