Am 22.07.2011 00:39, schrieb Karel Zak:
* bind mounts are represented as /A -> /B dependence, reality is
/A -> device, /B -> device (and /A could be umounted, moved, ...)
this is not generally true
look below
[root@srv-rhsoft:~]$ umount /Volumes/dune/www-servers
umount: /Volumes/dune/www-servers: device is busy.
(In some cases useful info about processes that use
the device is found by lsof(8) or fuser(1))
[root@srv-rhsoft:~]$ umount /Volumes/dune/www-servers/phpincludes
[root@srv-rhsoft:~]$ umount /Volumes/dune/www-servers
[root@srv-rhsoft:~]$ mount /Volumes/dune/www-servers/phpincludes
mount: Einhängepunkt /Volumes/dune/www-servers/phpincludes existiert nicht
[root@srv-rhsoft:~]$ mount /Volumes/dune/www-servers
[root@srv-rhsoft:~]$ mount /Volumes/dune/www-servers/phpincludes
[root@srv-rhsoft:~]$ cat /etc/fstab | grep www-servers
/mnt/data/www/thelounge.net /Volumes/dune/www-servers none bind
/mnt/data/www/phpincludes /Volumes/dune/www-servers/phpincludes none bind
so something, somewhere knows that one bind-mount is inside another
why this is configured this way?
because the /Volues/dune-Stuff is the physical structure of a
live-server and this way you can clone whole configurations
with whatever complexitiy on a development-machine with
a different physical disk-layout/structure
______________________________
another example of useing bind-mounts:
* 4x2 TB hard-disks
* RAID1 for /boot with 500 MB
* RAID10 for / with 30 GB
* RAID10 for data with the rest
another RADI for /home is wasting space
so /home lives on the data-disk and instead dealing with symlinks
or change /etc/passwd every part if the system can use /home
the same way as it would be a own partition and it is strictly
seperated from the operating system (damage, reinstall, whatever)