Also the filesystem needs to be unmounted before you can do this.
I would also question why you are enabling large files on /opt. Presumably your large files are some sort of data file, in which case they should really be on their own filesystem rather than on /opt which should remain fairly static.
AFAIK, the following must be done: fsadm -F vxfs -o largefile /dev/vg00/rlvolX and the file system can be mounted without the additional parameter in /etc/fstab. HTH
Entities are not to be multiplied beyond necessity - RTFM
the largefiles option in fstab technically isn't required. this won't enable largefiles on a filesytem without it enabled. all it will do is ensure that if a filesystem doesn't have largefiles enabled it won't mount it.
a filesystem that has been fsadm'd to enable largefiles will still support largefiles even if it's not specified explicitly in fstab.
Thanks for so many replies. One quick question is that, if I run " fsadm -o largefiles" option on my rvol4 then will my existing data will lost ? Because it's mine /opt partitioned & I want to use this for testing purpose.
Your files will not be lost, it will simply enable support for an extra inode level.
Of course it goes without saying that you should ensure you have a full backup of the filesystem before performing this or any filesystem administration task.
You don't need "-r" nor "/opt" in the command line.
The filesystem needs to be unmounted too so make sure you stop any services locking the filesystem ("fuser -c /opt" will tell you the processes using it). It may be easier with /opt to use single-user mode if there are a lot of things running, though it shouldn't be essential.
