ONM07@DMSWWU1A.BITNET (Operator Julian) (09/18/89)
Is there any documentation about the bad sector list format used by HDX? What is the meaning of the first 6 bytes? Any help appreciated!
tomas@m2cs.uu.no (Tomas Felner) (09/21/89)
ONM07@DMSWWU1A.BITNET (Operator Julian) writes: >Is there any documentation about the bad sector list format used by >HDX? What is the meaning of the first 6 bytes? Any help appreciated! I tried to figure out this myself some time ago, and even posted to the net, but no reply so far. However, I was able to decipher some of it myself. Here is my original posting from last march: _________________________ I just added a new harddisk to my selfbuilt harddisk-kit. The disk has some hard errors on the media as indicated on the cover of the disk. To map them out, I formatted it with the HDX 2.0 from Atari, which has a Markbad facility that generates a bad sector list (BSL). However, it didn't find all hard errors, and after running 'Markbad' a few times, I got several different BSLs. Two entries at the end of the bootblock indicate the first sector and the number of contiguous sectors holding the BSL. The BSL looks like this (3 real examples): 000002 550000 002DC8 002D2C ( 2 bad sectors ) 000003 AB0000 002DC8 002D2C 0003A6 ( a 3rd bad sector ) 000003 030000 00123F 002DC8 002D2C ( different ordering and another bad sector) It seems that the first entry indicates the number of bad sectors, and the third, forth, ... hold the number of the bad sectors. But what does the second entry mean ? Is it a checksum ? How to calculate it ??? Since this is the format used by Atari, I guess it will be 'official'. If I know what the second entry means, I can build the BSL by hand, adding the bad sectors not found by the formatter (you never know !). But how about handling that BSL. Does the TOS or any driver support it or even look at it ? Any comments ? Atari ? Or even better: the format-command of the Adaptec 4000 controller supports adding a BSL, so that the bad sectors are mapped out at format-time. Doing so, you don't have to worry about them any more, because they are not accessible. Is there any formatter around that accepts such a BSL as parameter ? BTW, how did you, netlanders, map out bad sectors before (or now) ? I was lucky not to have any bad sectors on my other harddisk so far. -------------------------- How about HDX 3.01 and the BSL ?? Tomas -- Tomas Felner Modula-2 CASE Systems AS | Internet: tomas@m2cs.uu.no Maridalsveien 139 | Phone: +47 2 379784 N-0461 Oslo 4, Norway | FAX: +47 2 356448
hcj@lzaz.ATT.COM (HC Johnson) (09/21/89)
In article <1989Sep20.174011.20782@m2cs.uu.no>, tomas@m2cs.uu.no (Tomas Felner) writes: > ONM07@DMSWWU1A.BITNET (Operator Julian) writes: > >Is there any documentation about the bad sector list format used by > >HDX? What is the meaning of the first 6 bytes? Any help appreciated! > > I tried to figure out this myself some time ago, and even posted to the > net, but no reply so far. However, I was able to decipher some of it > myself. Here is my original posting from last march: > The BSL is a place for bad sectors to be logged. TOS doesn't use it. ----Warning! This is my opinion:----- 1. most disk interfaces use the Adaptec 4000a or 4070 controllers to connect mfm or rll drives. 2. These adapters will accept a list of BAD BITS as part of the low level format command. This list is (i believe) standard, as my drives have such lists glued on them by the manufacturer. 3. After an Adaptec controller has formatted the drive using this list all of the sectors IMPLIED by the bits disappear. They do not appear in the BSL!. The user only finds that the drive contains a few fewer sectors that the full size. -- There is a SCSI command to adaptec to get this number. Only the BMS200 adapter can issue it however. -- Generally each bad bit area cost 1 sector. 4. HDX doesn't accept a bad bit list. (I modified my version to use the info). 5. HDX and (Supra/ICD, I believe) do a function called loosely, finding bad blocks. 6. What they really do is first partition the disk into GEM partitions and then test the data area for bad blocks, marking them bad in the FAT tables. 7. What happened to me was that the bad blocks were in the FAT and Root directory on one drive and this was a disaster. This is why I changed HDX. Howard C. Johnson ATT Bell Labs att!lzaz!hcj hcj@lzaz.att.com
BILL_FOSTER@bdt.UUCP (10/08/89)
I have written a Hard Disc Scan program called scan.arc and uploaded it to gEnie. If you run this just after formatting the drive you shouldn't have any more problems with read or write errors...
tomas@m2cs.uu.no (Tomas Felner) (10/09/89)
BILL_FOSTER@bdt.UUCP writes: >I have written a Hard Disc Scan program called scan.arc and uploaded it >to gEnie. If you run this just after formatting the drive you shouldn't >have any more problems with read or write errors... That's exactly what I need. But I don't have access to GENIE. Can you post it here (or rather to the binaries group) ? -- Tomas Felner Modula-2 CASE Systems AS | Internet: tomas@m2cs.uu.no Maridalsveien 139 | Phone: +47 2 379784 N-0461 Oslo 4, Norway | FAX: +47 2 356448