DOS ain't dead - MS Scandisk

fritz.mueller

Munich, Germany,
10.01.2025, 14:44

MS Scandisk (Announce)

Hi,
I only wanted to let you know that MS Scandisk for WinME is able to support Filesystemchecks for FAT32 and up to 2 TB. There is no "wrong DOS version" message when running it with FreeDOS.
I tested it in virtualbox on a 2 TB FAT32 HD, the basic checks run rather fast, but checking a 2TB HD surface lasts a few minutes more... :-P
Scandisk is available on WinME bootdisks, it only has to be extracted from there.

bencollver 10.01.2025, 15:01 @ fritz.mueller	MS Scandisk Post reply
	That's good to know! In FreeDOS, dosfsck seems to take forever and the fat16-only chkdsk is orders of magnitude faster. I can fix fat32 filesystems a little faster using my Linux system, but that kind of feels like cheating. ;)

mceric

Germany,
11.01.2025, 00:04

@ fritz.mueller

MS Scandisk

Post reply

Hi! How much RAM does scandisk need to check large FAT32 partitions?

Does this depend on how many files and directories are on the disk?

What types of problems does it check for and/or fix?

How fast is it compared to "DOSFSCK with enough RAM, no swapfile use"?

The last question is excluding surface scans. Those are a bad idea for most FAT32 disks anyway.

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FreeDOS / DOSEMU2 / ...

fritz.mueller

Munich, Germany,
11.01.2025, 13:43

@ mceric

MS Scandisk

Post reply

According to UI it runs the following:
Media descriptor
File allocation tables
Directory structure
File system
Free Space
Surface Scan

In virtualbox it works with 4 MB RAM, I do not know if it needs a swapfile.
On a test machine with up to 4 GB big test files it had a few problems
"One or more files on drive C are stored incorrectly and are overwriting each others data. Some of these files probably contain invalid data. To find out which files are involved, choose More Info.

1 invalid directory entry was corrected.
1 crosslink was corrected.
7 lost clusters were saved as files.

But I am not sure if this really has to say something; if I remember right I also tested an older version of edrdos which was able to create files bigger than 4 GB as it also supported a special format, i forgot the name, maybe FAT32+ (or something like this).
Speed is hard to compare, I will try to run both on a real machine.

> Hi! How much RAM does scandisk need to check large FAT32 partitions?
>
> Does this depend on how many files and directories are on the disk?
>
> What types of problems does it check for and/or fix?
>
> How fast is it compared to "DOSFSCK with enough RAM, no swapfile use"?
>
> The last question is excluding surface scans. Those are a bad idea for most
> FAT32 disks anyway.

ecm

Düsseldorf, Germany,
11.01.2025, 14:54

@ fritz.mueller

MS Scandisk

Post reply

> On a test machine with up to 4 GB big test files it had a few problems
> "One or more files on drive C are stored incorrectly and are overwriting
> each others data. Some of these files probably contain invalid data. To
> find out which files are involved, choose More Info.
>
> 1 invalid directory entry was corrected.
> 1 crosslink was corrected.
> 7 lost clusters were saved as files.
>
> But I am not sure if this really has to say something; if I remember right
> I also tested an older version of edrdos which was able to create files
> bigger than 4 GB as it also supported a special format, i forgot the name,
> maybe FAT32+ (or something like this).

Yes, FAT32+ or more generally FAT+ is the 6-bit file size extension that allows to store files of up to 256 GiB - 1 Byte. The specification for this is available at https://web.archive.org/web/20150219123449/http://www.fdos.org/kernel/fatplus.txt and it lists some compatibility concerns, like file system checks not supporting FAT+.

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