This is optical-disk in view mode; [Up]
Date: Sun 18-Jan-1989 18:35:20 From: Unknown Subject: optical disk This one really is causing problems! How do work around an optical disk with a non-correctable (see Release Notes) bad block? Also, how do you correct a trashed super block? I've tried fsck -b 16 /dev/od0a (its a 1 partition disk) ...eric >From: glasscoc@silver.bacs.indiana.edu (john glasscock)
Date: Sun 18-Jan-1989 23:40:28 From: Unknown Subject: Re: optical disk In article <4051@pt.cs.cmu.edu> eht@f.word.cs.cmu.edu (Eric Thayer) writes: >This one really is causing problems! How do work around an >optical disk with a non-correctable (see Release Notes) bad >block? Write down the PHYSICAL disk block address causing problems, then run the disk program (e.g., /etc/disk /dev/rod0a). Select the "abort" command, which disable the abort-on-error feature. Now, determine how many sectors have bad ECC. It is almost always 8 (for 8K) but is sometimes 1. To do this, execute the "read" command. It will prompt for several values: starting block: supply the PHYSICAL block you recorded earlier. # sectors per transfer: answer 1. number of transfers: answer 8. sector increment: answer 1. Now watch the error messages about bad ECC, you'll get either 1 or 8 of them, corresponding to how many sectors are bad. If you get no error messages, you've probably provided the wrong starting block. Start over! To "fix" these sectors, issue the "write" command, answering the questions as above (but for the number of transfers specify 1 or 8 depending on how many sectors were bad). Also, it will prompt you for "random data," say no, which will write zeros. What this does is to write the bad sectors, forcing good ECC. Unfortunately, you previous data there is lost. >From: ali@polya.Stanford.EDU (Ali T. Ozer)
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