keeping partitions mounted read-only

[Hans Wilmer <hwilmer@condor-werke.com>]

Hi!

Usually, I´m keeping partitions that can be mounted read-only, mounted that 
way. Especially the /usr partition is mounted ro.

To install security-updates (or new packages), I remount /usr by issueing a 
´mount /usr -o remount,rw´ so that the new software can be installed. After 
installation is finished, I remount the partition read-only by ´mount /usr 
-o remount,ro´.

But more or less frequently, the request to remount the partition read-only 
fails with a message like ´mount: /usr is busy´. This is utterly annoying 
as I haven´t found any other way than rebooting in order to get the 
partition mounted read-only again.

For example, I just installed the security upgrade of the man-db package on 
our mail server, and now I´m unable to remount the /usr partition read-only 
again. The mail server is use and I cannt reboot it now ... Another server 
is up for 271 days now, but the /usr partition is still mounted writeable 
since 200 days or so because of some software update, and an occassion to 
reboot it is not in sight.

Is there any way to do the remounting without a reboot?


GH