del@Data-IO.COM (Erik Lindberg) (05/18/88)
In article <661@mccc.UUCP> pjh@mccc.UUCP (Pete Holsberg) writes: >Misled? You think that the guys who told me that they were unable to >MFM-format a plated media drive that they had run under RLL were >kidding? Frankly, I didn't initially believe them either, but enough of >them said the same thing that I got rid of my ST-225 asap. Maybe it's >another hummingbird case: theoretically, there's nothing that an RLL >controller can do to prevent a disk from being reformatted, but in these >cited cases, it happened. Probably in conjunction with a powersupply >problem or some such thing, eh? No, it's not a hummingbird case. It's a case of brain damaged disk controller firmware. I saw this case once. After formatting a drive on an OMTI RLL controller, and finding that the drive would not hold the format reliably, I tried to reformat the drive MFM again on the original Western Digital XT controller. It would not take a format, just returned errors. I was able to force a low level format to the drive using a Datamac MFM controller card that I had, and it is working to this day as an MFM drive with only a single bad sector on it. The obvious conclusion is that the controller firmware (at least for the Western Digital controller) saw something on the disk that it simply couldn't deal with. Notes: 1) People that screw up installation of equipment are quick to blame the equipment. When peripheral equipment stops working also, then the new gizmo is assumed to have damaged the existing equipment. 2) Those same people will probably not listen to those with the technical expertise to explain reality. Reality is what their prior experience has shown them, regardless of what science says. 3) Had I not had the technical expertise to reason that RLL encoding could not possibly damage the drive, I would have been part of group 1). Instead, I tried other approaches until the issue was resolved. 4) Group 1) is the reason Seagate says you will void your warrantee if you use the ST225 with RLL. They just don't want to have to hassle with the morons out there. -- del (Erik Lindberg) uw-beaver!tikal!pilchuck!del
pechter@dasys1.UUCP (Bill Pechter) (05/21/88)
This is rather long so if you'd like to skip it go ahead, I won't tell. In article <900@pilchuck.Data-IO.COM> del@pilchuck.Data-IO.COM (Erik Lindberg) writes: > It's a case of brain damaged disk controller firmware. >I saw this case once. After formatting a drive on an OMTI RLL >controller, and finding that the drive would not hold the format reliably, >I tried to reformat the drive MFM again on the original Western Digital >XT controller. It would not take a format, just returned errors. > >I was able to force a low level format to the drive using a Datamac MFM >controller card that I had, and it is working to this day as an MFM drive >with only a single bad sector on it. The obvious conclusion is that the >controller firmware (at least for the Western Digital controller) saw >something on the disk that it simply couldn't deal with. I had the same problem. I picked up a Lapine 20 meg drive which I was unable to format on a number of different WD-1002-WX1 controllers. I put the darned thing on an BAD (would low level format but not read/write) Adaptec non RLL controller, low leveled it twice and then put it back on the WD where I then re-low leveled it and got me a 20 meg with 0 bad sectors for $30. (Thank you Trenton State Computer Festival :->) How about it WD. Anyone have any good explanation as to what's going on on the controller. I'd love to know what I did right and how this actually worked. I got the idea to switch controllers after I fixed my DEC Pro350's ST412 by low level format on my WD after the DEC controller came up with fatal errors initializing the drive. I work with SMD 300 meg and up disks every day and understand controllers -- but I can't figure out what's wrong here. The WD came up with errors like 22 or 25 and the manual said to check the connections between disk and controller. That obviously was not the problem. Here's my best guess as to what happens. I think the drive'd been RLL'd and the low level format was checking the header to check if it was on track (there'd be no header on the first time out for a new drive (right) and somehow it thought the RLL info was it's header and when I went to a different make controller the header was way off so it was ignored.) Anyone else have any info that can explain this to me? -- Bill Pechter {sun!hoptoad,cmcl2!phri}!dasys1!pechter USnail 103 Governors Road, Lakewood, NJ 08701 AT&T 201-370-0709 Evenings