kadafax <kadafax@gmail.com> wrote:
  

Thanks for reply Bryan,
in fact since the mounted FS is for backup purpose only,
it's not a big deal to un-mount it (far better than
disabling the ldap service with a reboot). I've checked
google and the result it gives seems to be too 
heavy for this production server (new scsi driver etc.). So
if you have a solution who is working on un-mounted volume,
I'm very interrested.
PS: The SAN is an AX100sc from EMC. The host adapter is a
QLA200 from QLogic. OS: CentOS 4.2
    

If all volumes are unmounted, then you can simply remove the
driver and modprobe it again.

E.g.,
  # /sbin/rmmod qla2200
  # /sbin/modprobe qla2200

I'm assuming your /etc/modprobe.conf file has all options
(SAN paths, etc...) for the card defined.

Once that is done, your /dev/sdb device should be updated to
reflect the new geometry of the storage.  Just add the new
space as a new, physical volume, add it to your existing
volume group, etc...