Recover a formatted disk

[jcrubin]

So I accidently chose the wrong drive to format and formatted one of my disks with mydos 4.5. Its no big deal, as it just had some common games on there and nothing lost forever.

 

 

I put the disk to the side with the question.... Can the disk be restored , perhaps with some utility?

 

 

Jordan

[Kyle22]

I'm afraid not. With MyDOS, a format is destructive. If it was a SpartaDOS disk, and you chose Build Directory, that is like a Quick Format in Windows, and the data is still in the sectors, then there is a possibility.

 

There may be some in-depth forensic tools to recover data, but that is far beyond the scope of what is possible on Atari compatible disk drives.

[+Larry]

The same is true with MyDos if you had chosen the /N switch/option when formatting. This is just a quick format. But recovering a bunch of files with no directory info. is no fun.

 

-Larry

[Rybags]

I'm not sure any Dos has the equivalent of Quick Format which only lays out new boot sector + wipes and initializes the directory/VTOC.

 

Hardware level format by the drive will write entire new tracks then read back to verify. If you flip the drive door open early on you'd just lose the first few tracks though the 810 drive at the least actually formats from last to first track.

Once the hardware format writes each track it would then be lost to any recovery except flux type reading where you'd probably need to offset from the tracks and hope that remnants of the old data could be recovered. And likely to be a time consuming process and not one possible with standard gear.

[flashjazzcat]

The same is true with MyDos if you had chosen the /N switch/option when formatting. This is just a quick format. But recovering a bunch of files with no directory info. is no fun.

 

The key difference is that there's no file link information in the SDX data sectors. I once had to recover several SDX files from their sector maps using DISKRX, and while it was laborious and time-consuming, at least the extracted sectors contained the file data and nothing but (aside from padding at the end of the final sector).

[+Larry]

If I were going to do this on MyDos, I'd read all of the sectors and list the link info in tables. You do have to make an educated guess as to which is the first sector but once you have that it should be fairly easy, barring cross-linked files. Pretty sure I've done this a couple of times over the years.

-Larry

[flashjazzcat]

I think I've been there as well. Recovering those SDX files was tough enough.

[fujidude]

Probably obvious by now, but if you can get the files that were on that disk from somewhere else, or if not they weren't very important: then as they say in NY, "forget about it."

[russg]

So I accidently chose the wrong drive to format and formatted one of my disks with mydos 4.5. Its no big deal, as it just had some common games on there and nothing lost forever.

 

 

I put the disk to the side with the question.... Can the disk be restored , perhaps with some utility?

 

 

Jordan

Formatting it writes the first 3 sectors and puts '0's in all the other sectors. So, no, you can't retrieve your files from it. Hope you had backups of them.

I'm not sure what the first 3 sectors are, maybe the VTOC (variable table of contents).

Edited May 17, 2015 by russg

[+CharlieChaplin]

I'm not sure any Dos has the equivalent of Quick Format which only lays out new boot sector + wipes and initializes the directory/VTOC.

 

Hardware level format by the drive will write entire new tracks then read back to verify. If you flip the drive door open early on you'd just lose the first few tracks though the 810 drive at the least actually formats from last to first track.

Once the hardware format writes each track it would then be lost to any recovery except flux type reading where you'd probably need to offset from the tracks and hope that remnants of the old data could be recovered. And likely to be a time consuming process and not one possible with standard gear.

 

Well,

 

several A8 DOS versions (SuperDOS, Turbo-DOS, etc.) do have this function, it is usually named "clear disk" and does exactly what you say - clear DIR, VTOC and Boot sectors without any formatting. Turbo-DOS also has a Diskfix tool which can not only undelete/recover deleted files, but it can also recover whole disks/directories which were "damaged" with quick format/clear disk or which do have "hidden" files on it. But TurboDOS Diskfix works only on TurboDOS (DOS 2.0 and DOS 2.5 compatible) formats - it does not work with MyDOS formats (130k, 360k etc.).

 

One can try Diskfix e.g. with some copy protected original disks from LK Avalon, just make a copy of them (ignore all read errors) and then use TurboDOS Diskfix to recover the Directory on the backup. The ML-file you will find after scanning the whole disk can be loaded from DOS or Gamedos and does not have (nor check for) any copy-protection...

 

Alas, if the A8 disk is really formatted in 90k/130k/180k/... format then all data is gone and there is no tool to recover it.

Edited May 17, 2015 by CharlieChaplin

[hunter44102]

It takes like 300 seconds to read a 180k disk on Atari 8, and it takes like 4 seconds to format it (SpartaDOS). So logic tells me that data is not lost in 4 seconds. Just need a way to re-build the directory

[_The Doctor__]

all theory aside, a sector editor that works in the format that was on the lost disk will tell the tale, scan through with the sector editor... if you find some recognizable data you might recover something.. if its all the same from beginning to end ... it's gone.... not sure if kryo or scp would help.... a chance it might be on the edges of the stream but very slight... as you move from the center of a stream it becomes weaker and more scattered and well lets face it error prone it's the nature of magnetic media encoding...

Edited April 15, 2017 by _The Doctor__

[Rybags]

For a disk that was actually reformatted on drives that don't use the index hole, the sector layout is "random" in relation to what was previously there, ie the track starts to be recorded at a different position than what was there before.

Chances are the forensic methods use in labs would probably work but you're trying to detect weak flux transitions going against what now exists there.

Maybe some sort of subtractive method would work - once you read the "new" track data you know what's there, then re-read it as an analog value and subtract what's already there which might reveal the weak signal of the "old" track data.

 

But really, would any home-gamer have gear that could do this sort of thing?

[_The Doctor__]

That is a much better explanation of what I am getting at. this is the same technique I attempt to use on disks that have been mil spec wiped... drift allows you to see in between those fixed sectors, and a good deal of recovery tools don't look there. the floppy drives, other than the XF551 or standard mech drives, do not use the index and lend themselves to this better as you can look at the edges of a sector for data not just in the stream of a track but also by the edges of a stream in a track...you can look at sector and a fraction but also track plus a fraction and find information... very few know to look that far....a heck of a lot to go through... but possible. in fact when a physical crash occurs that technique can sometimes obtain data that many recovery services deem impossible.. they don't look to the side of the damage!

 

All things being equal we are going to the extremes in this particular conversation... on the other hand a one of a kind preservation by sharing this knowledge would be pretty cool....

Edited April 16, 2017 by _The Doctor__

[+Larry]

Or, you could keep a backup on an ATR...

 

-Larry