Question: read-only array

Hi

I've just noticed that setting an array readonly doesn't really make
it readonly.

I have a RAID1 array and LVM on top of it.

When I run 

/sbin/mdadm --misc --readonly /dev/md0

/proc/mdstat shows:

Personalities : [raid1]
md0 : active (read-only) raid1 sda[0] sdb[1]
      160436096 blocks [2/2] [UU]

However, it doesn't prevent me from activating volume groups, mounting 
filesystems and write files onto it.

Is it a bug, feature or my misunderstanding of the meaning of readonly flag?


I use RedHat AS 4 (U1) on a dual core Opteron machine.
Kernel 2.6.9-11.ELsmp as delivered with RH.

mdadm - v1.12.0 - 14 June 2005

Thanks for your time.

Regards,
Chris