при выполнении
Command (m for help): w
The partition table has been altered!

Calling ioctl() to re-read partition table.

WARNING: Re-reading the partition table failed with error 22: Invalid argument.

The kernel still uses the old table.
The new table will be used at the next reboot.
Syncing disks.

Заребутил, после ребута

при выполнении команды
mkfs.ext3 /dev/hda6p1
Could not stat --- No Such File or Directory
the device apparently does not exist; did you specify it correctly?