On Monday February 6, [EMAIL PROTECTED] wrote: > > 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? >
It should prevent you from mounting a filesystem writable directly on the md array, but I can see from the code that it won't stop a lot of other write accesses such as including it in an LVM set, or in an md array, or (I think) simply opening it and writing to it. Basically, the readonly 'policy' doesn't seem to be implemented very uniformly in the kernel. This is not something particular to md. I suspect other devices that are flagged 'readonly' will not always be treated the way you expect. I've put it on my todo list to look into this some more, but I cannot make any promises. Thanks for the report. NeilBrown > > 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 > - > To unsubscribe from this list: send the line "unsubscribe linux-raid" in > the body of a message to [EMAIL PROTECTED] > More majordomo info at http://vger.kernel.org/majordomo-info.html - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
