Bad sectors on SCSI drive

2 replies [Last post]
Derek Spencer
Joined: May 6 1999

PC showed symptoms of overheating after being in use for 2-3 hours.(possibly due to the DC30+ card which runs very warm indeed) Intermittent messages "Unable to write to D Drive" (SCSI)or "Illegal operation etc" coupled with file corruption. Running Scansdisk identified a gradual build up of bad sectore towrads the end of the surface scan. An additional 4" extractor fan was fitted towards the top of the tower.

QUERY Can Scandisk be configured to reexamine the previous sectors/clusters marked as BAD? Alternativley are there any pitfalls in Reformatting the SCSI drive (used for video clip storage during editing only) ?

many thanks

Joined: Mar 27 1999

There are lots of folk out there who know much more than me, but I use SCSI drives and reformat them regularly, on the advice of my supplier. As far as I can see, from the way they perform, no harm is being done.
Best wishes.

Mark Brookes
Joined: Apr 26 1999

If you do not wish to reformat your disk on a regular basis the following maybe a solution. This worked for me with an identical problem with a SCSI disk that was the boot disk of a PC, actually it was the only disk in the PC and reformatting was not really an option. Also reformatting is no guarentee that the problem you describe will be solved as this will simply mark those sectors that are bad as bad, any sectors nearby that are OK but deteriorating will still be marked good by the drive and present disk errors when they eventually fail.

The following worked on Win 95 and a SCSI drive but should also work for IDE disks.

If you do not understand any of the following it would be wise to seek the help of someone who does.

1: Run Defrag /full.

2: Fill the disk with files that are about 1% of the capacity of the drive giving each one a sequntial number.

3: Run Scandisk without the surface scan option, i.e. files only. When Scandisk is reading the dodgy area you should see one or more files experience an increased access time or multiple read attempts to sucessfully be retieved. Make a note of the filenames at this point. Also note the files immediatly before and after the problem files.

4: Move the noted files into a directory (on the same disk) you have created called 'DO NOT DELETE'. (Do not copy the files and delete the originals)

5: Set the attibutes of the files in this directory to HIDDEN, SYSTEM and READ ONLY.

6: Delete all the other files used (i.e. the good ones)

You should now have a disk where the bad area has files on it that cannot be accessed normally, similar to a bad sector list when formatting, but which occupies the whole region where the disk is deteriorating. You will have lost a few percent of the capacity of the disk but that dodgy area should never trouble you again as long as you follow instruction 7:

7: DO NOT run any Defragmenation utility on the disk as this will move the files in the dodgy area to a good area undoing all the work above.

Have Fun!