RA81 disk error/dump problem

[Alan's Home for Wayward Notes File.]

In article <1091 at wsu-cs>, jjb at ares.cs.wayne.edu (Jon J. Brewster) writes:
> This concerns a uVAX3600 running Ultrix V3.1.  We've recently started
> having problems with dump -- we get lots of bread messages with block
> no.s and a final one that says "More than 32 block read errors from
> 64884"  Uerf shows many bad block replacement events for that disk, all
> for the same LBN, 177837.  However, it also lists "PREVIOUS RBN 0." and
> "NEW RBN 0.".  I assume that RBN means Replacement Block Number.  It
> also says BAD BLOCK REPL CAUSE x0048.

	I haven't studied the BBR algorithm closely enough to
	see what is really going on, but it sounds like something
	is causing BBR to break.  I saw a problem similar to this
	on an V3.x field test, but it was fixed.  As a guess it
	could be the RCT is corrupted and causing BBR to fail in
	mysterious ways.  Generally when BBR doesn't work you'll
	get message like:

		Media is write-protected.
		Back up media and reformat.
> 
>  Jon J. Brewster
>  jjb at cs.wayne.edu
>  ...!umich!wsu-cs!jjb

	For reference:

		RBN - Replacement Block Number.
		RCT - Replacement Control Table.

	LBN numbers from radisk are reported relative to the beginning
	of the disk, where most other ULTRIX utilities report block
	numbers relative to the file system (partition).

	Solution?  You'll want to back up as much as the disk as
	you can.  Since dump doesn't work try tar, but you'll need
	to avoid the file with the messed up blocks.  Since ncheck
	and icheck are being useless try find and cp:

		find file-system -print -exec cp {} /dev/null \;

	After getting a back up have Field Service format the disk.

-- 
Alan Rollow				alan at nabeth.enet.dec.com