Trouble reading FAT32 created in QNX in Windows

Mark_Dornbush1 · April 7, 2005, 2:52pm

I would like some help to know the proper steps for formatting a HD to FAT32
under QNX 6.3. What ever I try, the HD seems to format OK in QNX but the
available space always reports “0” in Windows.

I have tried the following (in various combinations):

dd if=/dev/zero of=/dev/hd1 count=100
mkdosfs -F32 /dev/hd1
mount -t dos /dev/hd1t11 /fat32

or

fdisk /dev/hd1 delete -a
fdisk /dev/hd1 add -s1 -t11
mkdosfs -F32 /dev/hd1
mount -t dos /dev/hd1t11 /fat32

or

fdisk /dev/hd1 delete -a
fdisk /dev/hd1 add -s1 -t11
dinit -h /dev/hd1t11
mount -t dos /dev/hd1t11 /fat32

In each case, I can use the FAT32 under QNX, but Windows reports it as
having no free space. If I format the drive under Windows as a FAT32, I can
write to it under Windows and QNX.

I would like to be able to format the drive in QNX and access it under
Windows. The drive is removable. 95% of the time it is used in QNX, the 5%
of the time it is put into a Windows computer for configuration and backups.

Thanks,
Mark

ed1k2 · April 12, 2005, 4:28am

In article <d33h89$l3v$1@inn.qnx.com>, “Mark Dornbush” <markxd(delme)
@cyberdude.com> says…

I would like some help to know the proper steps for formatting a HD to FAT32
under QNX 6.3. What ever I try, the HD seems to format OK in QNX but the
available space always reports “0” in Windows.

I have tried the following (in various combinations):

dd if=/dev/zero of=/dev/hd1 count=100
mkdosfs -F32 /dev/hd1
mount -t dos /dev/hd1t11 /fat32

or

fdisk /dev/hd1 delete -a
fdisk /dev/hd1 add -s1 -t11
mkdosfs -F32 /dev/hd1
mount -t dos /dev/hd1t11 /fat32

or

fdisk /dev/hd1 delete -a
fdisk /dev/hd1 add -s1 -t11
dinit -h /dev/hd1t11
mount -t dos /dev/hd1t11 /fat32

I bet you missed the right combination:

fdisk /dev/hd1 delete -a
fdisk /dev/hd1 add -s1 -t11
mkdosfs -F32 /dev/hd1t11
mount -t dos /dev/hd1t11 /fs/fat32

Eduard.

Mark_Dornbush1 · April 14, 2005, 5:34pm

This didn’t help. These are the commands I used:

fdisk /dev/hd1 delete -a
fdisk /dev/hd1 add -s1 -t11
mount -e /dev/hd1
mkdosfs -F32 /dev/hd1t11
mount -t dos /dev/hd1t11 /fat32

After the above commands, output of df -g /fat32:

/dev/hd1t11 /fat32/
Blocks: 62589 total 62588 avail [4096-byte blocks]
Files : 0 total 0 avail
Type : dos (fat32)
Flags : 00000100 [32bit]

After the above commands, output of df -kP:

Filesystem 1024-blocks Used Available Capacity Mounted on
/dev/hd0t77 96186 61569 34616 65% /
/dev/fd0 1423 556 867 40% /flop/
/dev/hd1t11 250356 4 250352 1% /fat32/
/dev/ram0 51200 3469 47731 7% /ram/
/dev/hd1 250880 250880 0 100%
/dev/hd0 96192 96192 0 100%

Other things I have tried:

Disk formatted under QNX reports reports FAT32, disk always full, in WinXP.

Disk formatted under QNX reports UNKNOWN system type in FDISK and “Invalid
drive specified” trying to access the drive from the command prompt in
Windows 98 SE.

I used FDISK and formatted the disk under Windows 98 SE and had no problems.

I used WinXP’s format utility on the disk and had no problems.

When I format the drive under QNX to FAT32 it is only writeable under QNX.
I need it to be writeable under Windows.

I have QNX tech support involved now but they aren’t sure what the problem
is.

Thanks,
Mark

“ed1k” <ed1k@fake.address> wrote in message
news:MPG.1cc5187c29042f229896ad@inn.qnx.com…

In article <d33h89$l3v$> 1@inn.qnx.com> >, “Mark Dornbush” <markxd(delme)
@cyberdude.com> says…
I would like some help to know the proper steps for formatting a HD to
FAT32
under QNX 6.3. What ever I try, the HD seems to format OK in QNX but the
available space always reports “0” in Windows.

I have tried the following (in various combinations):

dd if=/dev/zero of=/dev/hd1 count=100
mkdosfs -F32 /dev/hd1
mount -t dos /dev/hd1t11 /fat32

or

fdisk /dev/hd1 delete -a
fdisk /dev/hd1 add -s1 -t11
mkdosfs -F32 /dev/hd1
mount -t dos /dev/hd1t11 /fat32

or

fdisk /dev/hd1 delete -a
fdisk /dev/hd1 add -s1 -t11
dinit -h /dev/hd1t11
mount -t dos /dev/hd1t11 /fat32

I bet you missed the right combination:

fdisk /dev/hd1 delete -a
fdisk /dev/hd1 add -s1 -t11
mkdosfs -F32 /dev/hd1t11
mount -t dos /dev/hd1t11 /fs/fat32

Eduard.

Mark_Dornbush1 · April 15, 2005, 2:00pm

I received my reply from QNX Tech support today. The trouble was with the
mkdosfs utility. The utility always defaulted to a FAT32 cluster size of 4K
but I was using smaller disks which needed a cluster size of 2K. Windows
was confused by the 4K size.

QNX Support said they would change / fix mkdosfs in the future. Until then,
I will use the “-c” option to mkdosfs to force the smaller cluster size. I
found the table below on Microsoft’s web site.

Volume Size FAT16 Cluster Size FAT32 Cluster Size NTFS Cluster Size
7 MB-16 MB 2 KB Not supported 512 bytes
17 MB-32 MB 512 bytes Not supported 512 bytes
33 MB-64 MB 1 KB 512 bytes 512 bytes
65 MB-128 MB 2 KB 1 KB 512 bytes
129 MB-256 MB 4 KB 2 KB 512 bytes
257 MB-512 MB 8 KB 4 KB 512 bytes
513 MB-1,024 MB 16 KB 4 KB 1 KB
1,025 MB-2 GB 32 KB 4 KB 2 KB
2 GB-4 GB 64 KB 4 KB 4 KB
4 GB-8 GB Not supported 4 KB 4 KB
8 GB-16 GB Not supported 8 KB 4 KB
16 GB-32 GB Not supported 16 KB 4 KB
32 GB-2 terabytes Not supported Not supported1 4 KB

1Windows XP Professional formats FAT32 volumes up to 32 GB regardless of
cluster size. To format volumes larger than 32 GB, you must use NTFS.
However, Windows XP Professional can mount FAT32 volumes larger than 32 GB
that were created by other operating systems.

“Mark Dornbush” <markxd(delme)@cyberdude.com> wrote in message
news:d3m9b2$hmh$1@inn.qnx.com…

I have QNX tech support involved now but they aren’t sure what the problem
is.

Mark_Dornbush1 · April 15, 2005, 2:56pm

Outlook Express mangled the table. You can find it here:

http://www.microsoft.com/resources/documentation/Windows/XP/all/reskit/en-us/prkc_fil_lxty.asp?frame=true

“Mark Dornbush” <markxd(delme)@cyberdude.com> wrote in message
news:d3oh9r$7re$1@inn.qnx.com…

I received my reply from QNX Tech support today. The trouble was with the
mkdosfs utility. The utility always defaulted to a FAT32 cluster size of
4K but I was using smaller disks which needed a cluster size of 2K.
Windows was confused by the 4K size.

QNX Support said they would change / fix mkdosfs in the future. Until
then, I will use the “-c” option to mkdosfs to force the smaller cluster
size. I found the table below on Microsoft’s web site.

Volume Size FAT16 Cluster Size FAT32 Cluster Size NTFS Cluster Size
7 MB-16 MB 2 KB Not supported 512 bytes
17 MB-32 MB 512 bytes Not supported 512 bytes
33 MB-64 MB 1 KB 512 bytes 512 bytes
65 MB-128 MB 2 KB 1 KB 512 bytes
129 MB-256 MB 4 KB 2 KB 512 bytes
257 MB-512 MB 8 KB 4 KB 512 bytes
513 MB-1,024 MB 16 KB 4 KB 1 KB
1,025 MB-2 GB 32 KB 4 KB 2 KB
2 GB-4 GB 64 KB 4 KB 4 KB
4 GB-8 GB Not supported 4 KB 4 KB
8 GB-16 GB Not supported 8 KB 4 KB
16 GB-32 GB Not supported 16 KB 4 KB
32 GB-2 terabytes Not supported Not supported1 4 KB

1Windows XP Professional formats FAT32 volumes up to 32 GB regardless of
cluster size. To format volumes larger than 32 GB, you must use NTFS.
However, Windows XP Professional can mount FAT32 volumes larger than 32 GB
that were created by other operating systems.

“Mark Dornbush” <markxd(delme)@cyberdude.com> wrote in message
news:d3m9b2$hmh$> 1@inn.qnx.com> …

I have QNX tech support involved now but they aren’t sure what the
problem is.