physical disk access

Fri Dec 31 13:28:00 GMT 1999

Bob McGowan wrote:
> [...]
> I wanted to use dd to verify disk sizes on reads and writes, so I used
> the following two commands:
>> dd if='\\.\F:' of=/dev/null bs=1024k
> zero | dd of='\\.\F:' bs=1024k
>> where the command zero just generates null bytes on standard out.
> [...]
> I would have expected dd to work for both in and out operations under
> these circumstances. Any idea why it didn't?
>> I am running the Cygwin 1.0 environment from the CD, no updates.

If you want to use raw devices with cygwin you have to mount them.
Some examples:
 mount -f -b -s //./F: /dev/hdb2 # partition
 mount -f -b -s //./physicaldrive0 /dev/hda # hard disk
 mount -f -b -s //./tape0 /dev/st0 # rewind tape
 mount -f -b -s //./tape0 /dev/nst0 # same as norewind
In further commands you have to use the mountpoints for correct
results:
 dd if=/dev/hdb2 of=/dev/null bs=1024k
 zero | dd of=/dev/hdb2 bs=1024k
Hope, this helps,
Corinna
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