SCSI harddrives...

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omelette
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SCSI harddrives...

Post by omelette »

Question, what is the outcome of sticking a big (say, 40mm x 5mm disk) magnet to the back of a SCSI drive? Read on to find out.

I've just had something of a melt-down with my Atari ST setup. i had two SCSI drives, a 243Meg Maxtor and a 1Gig Seagate to backup the Maxtor & Falcon drives. I've had problems with both for ages. Bad-sector scans seemed respectable - >20 for the Maxtor, whereas the much larger Seagate had only 6. But both were suffering more & more from directory corruption, with entire drives quickly becoming unreadable. Seeing the writing on the wall, I spent a futile 4hrs copying by floppy, from the Maxtor, to the pc, stuff I considered 'sacred'. I managed just 30meg! On the very next reboot, the Maxtor had zero drives being logged - a first! Booting from the Seagate, which had a 20 year old backup of the Maxtor, I resolved to back up the lot over a parallel-printer cable using 'PARCP' - https://joy.sophics.cz/parcp/ - something I bought in the 90's but had mixed results with. But it proved a God-send in this instance, though it took all of 12 hours to back-up 600meg!

I then decided a format of both drives was in order. The Maxtor when bought 2 years ago, had over 40 bad sectors. After a successful reformat, a real surprise in itself, it had only 2. I was elated. But it was all down-hill from there. The Seagate refused point-blank to format at all with HDDRIVER, the German s/w, but the attempt had wiped the partition data, rendering the drive useless. With ICD's HDUTIL, on the second attempt, I succeeded in reformatting the drive, but it then failed to write partition data, recommending that I reformat the drive & try again. Which I did, dozens of times, all without success. But at least the drive was trying to format itself. Admitting defeat, I thought before chucking it out, I'd check to see what effect sticking a very powerful neo-magnet on the back of it would have - I figured, no effect, as everything I had read suggested that only IDE drives suffered from the form of 'low-level' wipe, and a SCSI was just like a floppy - the FDC, or HDC in this case, would recreate all of the vital formatting data. Apparently, this is not the case. Immediately after doing this, when I attempted to format it, it would come straight back with a $FE sense-error - no more format-able I presume, although I couldn't find info on what that code means. Later that changed to $1c, and stuck with that.

With nothing else to try, I opened up the drive for a looksie. Gotta say, the disks I could see looked almost perfect, and little bits of white stuff, mostly near the edge came off easily with some isopropyl alcohol. I then wondered if I had somehow magnetised the surface of the disk, and this was what was throwing up the $FE error-code. So using a powerful diametrically-magnetised neo on the end of a dremel, I had a go at 'degaussing' the sucker.

All for naught though, any attempted reformat would produce the same error. So, it looks like that, contrary to personally held beliefs, SCSI drives come with low-level format data from the factory, that cannot be reproduced - once wiped, your drive's toast. Good to know, just wish I had known it sooner - though I'm sure the drive was unusable anyway. Of course, with only 6 bad sectors, I could instead of reformatting,have just wiped the partition data...

Since there's little hope of getting a time-machine,I suppose I better start looking for another SCSI drive on Ebay.

ThomH
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Re: SCSI harddrives...

Post by ThomH »

If it's any help, SCSI command 4 is 'format unit' but the ECMA spec explicitly says: "The FORMAT UNIT command ensures that the medium is formatted so that all data blocks can be accessed. There is no guarantee that the medium has or has not been altered."

So to my reading, an individual SCSI drive has the choice to low-level format or not, whatever its controller prefers.

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Dbug
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Re: SCSI harddrives...

Post by Dbug »

I did have an awesome 1GB Micropolis drive in my Mega STE, with zero sector defect. When I moved to Norway, the thing died.

Personally, I've abandoned the idea of using real harddrives on the ST, because losing a floppy is "ok", but losing an entire hard drive is a major issue, instead I recommend investing a similar amount of money in something like the CosmosEx, which basically gives you fast and silent harddrives, but also network share so you can have your ST show a disk unit which happens to be mounted on some PC somewhere - super useful for debugging, developping or making backups.

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Symoon
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Re: SCSI harddrives...

Post by Symoon »

I've bought an UltraSatan a while ago and I've been really happy with it.
Still have the whole "Link II" things for SCSI, but haven't used it in years.
(That being said, I don't plug the ST every day... A few times a year, at best).

omelette
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Re: SCSI harddrives...

Post by omelette »

Yeah, I hear what you're saying guys about going a more hi-tech approach, it would certainly be less stressful, that's for sure. But I prefer to deal with 'tech-of-the-day' when at all possible. Seeing the prices being asked for 50-pin SCSI drives these days, and it would probably be cheaper to go hi-tech. I bought that 243Meg Maxtor a few years ago for $58, which included P&P, and though I didn't think so at the time, that' price is looking quite reasonable now. U320 SCSI drives are available at much cheaper prices and I'll probably end up getting one of those instead, though the 80-pin -> 50-pin adapter will set me back another $10 - but at least the option is still available. But then, there's no guarantee that the formatting s/w available will even work with them. Decisions, decisions...

I'd love to find some definitive information on SCSI formatting though - do the platters contain some form of 'pre-formatted' data, done during manufacturer, that if wiped, renders the harddisk useless. From what I experienced, that would appear to be the case, but I'd like some confirmation of this. Wikipedia's article tells you that harddrive formatting is much misunderstood, then goes on to give a watered-down version of what's taking place, doing nothing to clear up the misunderstanding.

I do know first-hand that another disk, the zip-drive comes 'pre-formatted' from the factory. Once this formatting is wiped or degrades with time, your disks are worthless. I have a bunch of 250meg zip-disks that hadn't been used for well over a decade and was dismayed to discover that most were barely readable. I decided to subject one of them to my 'magnet-test', and sure enough, I ended up with one useless disk. I really should get rid of those magnets! I later came across an article from someone who has probably researched the subject more than anyone else on the planet. He had even managed to contact an Iomega engineer, who confirmed that, yes, once the factory-formatted data degrades/is-erased, the disks are worthless. Which really pissed me off to read, as I paid £15 for each of them. Definitely a case of planned-obsolescence by Iomega.

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coco.oric
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Re: SCSI harddrives...

Post by coco.oric »

I've bought an UltraSatan a while ago and I've been really happy with it.
So, if i want to copy some st disks on my satan sd card, then getting them on my pc, i know where ask the question :)
coco.oric as DidierV, CEO Member
Historic owner of Oric, Apple II, Atari ST, Amiga

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Dbug
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Re: SCSI harddrives...

Post by Dbug »

coco.oric wrote:
Tue Jan 21, 2020 7:21 am
I've bought an UltraSatan a while ago and I've been really happy with it.
So, if i want to copy some st disks on my satan sd card, then getting them on my pc, i know where ask the question :)
The difficulty is to find the combination of formating options that work for the two cards, the device, the atari, and whatever hard drive driver you decided to go with. After that it's trivial: Keep the left card in the device at all time (the one formatted in Atari format), and the secondary card is using a MSDOS compatible format, and is handled as "hot swap", so it's really just a matter of removing the card, put it on the PC, save the files, back on the atari, refresh the windows, done :)

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Symoon
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Re: SCSI harddrives...

Post by Symoon »

I've bought HDDriver long ago and there's an option to format up to 512Mb Windows-compatible partitions. So at the time, I bought a few 512Mb SD Cards, and I can put them in a PC, copy the files, have them back into the UltraSatan and boot the ST with them.
I'm happy with it ever since !

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