From:	SMTP%"RELAY-INFO-VAX@CRVAX.SRI.COM" 10-SEP-1993 13:42:57.44
To:	EVERHART
CC:	
Subj:	Re: RD 54 Bad Blocks, Any Fix?

From: cornelius@eisner.decus.org
X-Newsgroups: comp.os.vms
Subject: Re: RD 54 Bad Blocks, Any Fix?
Message-ID: <1993Sep9.091951.520@eisner.decus.org>
Date: 9 Sep 93 05:19:51 GMT
Article-I.D.: eisner.1993Sep9.091951.520
Organization: DECUServe
Lines: 84
To: Info-VAX@KL.SRI.COM
X-Gateway-Source-Info: USENET

In article <36205@suned1.Nswses.Navy.MIL>, bill@TASVAX.NSWSES.NAVY.MIL (Bill Litwin) writes:
> 
>   I've seen the recent posts about RA 81s and bad blocks, and would like
> any information about a similar problem with RD 54 drives and bad blocks.
> Basically, is there any way to update the bad block table for an RD 54. 
> 
>   We're running a MicroVAX II, VMS 5.4-1, that has a pair of RD 54s running 
> off a RQDX3 controller.  Both the drives and controller are late 1988 vintage 
> and have been in continuous use as system and user account drives until about
> a month ago.  Naturally, documentation for the drives and controller are long 
> lost.


A bit late, I know, but a few of comments:

 1. When you start to get lots of bad blocks, it's probably time
     to trash the device (or the HDA).

 2. If you are getting errors in one of your files, are your sure
     it's not the "forced error" bit being set?  When a block is
     revectored and the old block is unreadable, your new block will
     be marked with a "forced error" bit until it is next written.

 3. If the block is really bad, it will be revectored when you try to
     use it, so there's no need to add it to the bad block file.  If
     you have run out of revectoring capacity, you might as well toss
     the drive anyway, because it will be nothing but a headache for
     you in the future.

 4. If you really _must_ add specific blocks to a file, there are
     ways, including a MACRO program like the one below.

George Cornelius                          cornelius@eisner.decus.org
                                          cornelius@mayo.edu

--
;RmsExtend.MAR GFC 911117 Experimental program extend a file
;
; 930909 Modified version - specific LBN to be added
;
	.TITLE	RmsExtend
;
; Extend INFILE (logical name must refer to file to extend)
; LBN to add is hardcoded below
;

	.PSECT		DATA,RD,WRT,NOEXE,QUAD

StartLBN = 719236	; Hard code the LBN here

FileFab:	$FAB	FNM=<INFILE:>,FAC=<GET,PUT>
;
; Info about the type of extend goes here
;
ExtendXAB:	$XABALL	ALQ=1,AOP=<CTG,HRD>,ALN=LBN -
			 ,LOC=StartLBN

;
; ENTER HERE
;
	.PSECT		CODE,RD,NOWRT,EXE,LONG

.ENTRY			RmsExtend,^M<>

	$OPEN		FAB=FileFAB
	 BLBC		 R0,Exit

	$FAB_STORE	FAB=FileFAB,XAB=ExtendXAB
	$EXTEND		FAB=FileFab
	 BLBC		 R0,Exit

	$CLOSE		FAB=FileFab

EXIT:

	RET				; Back to VMS.

	.END		RmsExtend

> ------
> Bill Litwin
> Part Time (Try-Not-To-Break-It-While-Learning) VAX Manager,
> BILL@TASVAX.NSWSES.NAVY.MIL
> 

