[Courses] mounting floppy

[Devdas Bhagat]

On 04/08/04 11:57 -0700, Mag Mu wrote:
> Hello!
> 
> After mounting my floppy, I wrote a test file.  Now I
> cannot umount /mymount/ even after removing the file. 
> Also, nothing was actually written to the physical
> disk.  

Wrong list. Please post to newchix, or techtalk.
I am not CC'ing either list, because I don't see a long discussion on
this coming up.

> 
> So, 2 questions:
> 1.  When is data actually written to the physical
> disk?

When you use a removable slow medium like a floppy disk, Linux buffers
the write until you unmount the medium, or until you call sync.

> 2.  How do I unmount the floppy?

<snip>
Transcript left for comparison.

> Here is a transcript of what I did:
> [root at localhost mymount]# mount -t vfat /dev/fd0
> /mymount/
> 
> [root at localhost mymount]# vi test
> 
> [root at localhost mymount]# ls
> test
> 
> [root at localhost mymount]# umount /mymount/
> umount: /mymount: device is busy
> 
> [root at localhost mymount]# rm test
> rm: remove regular file `test'? y
> 
> [root at localhost mymount]# ls -l
> total 0
> 
> [root at localhost mymount]# umount /mymount
> umount: /mymount: device is busy
> 
> [root at localhost mymount]# ls -l
> total 0
> 
I don't have a floppy disk drive here, so I can't do a real transcript,
but here is an attempt anyway. The // marks a comment, # is for a root
prompt, and $ is for my regular user prompt.

# With /mnt/floppy in /etc/fstab, I could just use 
# mount -t vfat /mnt/floppy
# I can also ignore specifying the fstype explicitly and let Linux do
# the guesswork
# mount /mnt/floppy works quite well

[devdas at evita devdas]$ mount -t vfat /dev/fd0 /mnt/floppy

# At this point I am accessing the floppy.
[devdas at evita devdas]$ cd /mnt/floppy

# List files on the floppy
[devdas at evita floppy]$ ls

# Create a file
[devdas at evita floppy]$ touch file

# List again
[devdas at evita floppy]$ ls
file

# Move out prior to unmounting the disk
# While I am in the /mnt/floppy directory, there are open filehandles and
# that causes trouble with the unmout call.

[devdas at evita floppy]$ cd ..

# This unmounts the floppy and forces data to be written to disk.
[devdas at evita mnt]$ umount floppy
[devdas at evita mnt]$ 

I hope this helps.

Devdas Bhagat