> I think how AIX does it is they tune the file system parameters so that
> the cylinder group size is the same as the PP size (Physical Partition, LV
> allocation unit, 4 MB on the boxes I ran). That way growing is just adding
> a whole cylinder group.

That shouldn't be necessary - aren't the blocks in the last cylinder
group just marked 'allocated' - so once there is physical space
backing them they can freed (so they can be allocated to files).

Shrinking a live filesystem is also possible, the only real
difficulty I can see is that some inodes have to be renumbered.
This will, in particular, cause grief if the file system is NFS
exported (or has anything else that is using file handles).

	David

-- 
David Laight: david@l8s.co.uk