On Fri, 2008-05-02 at 13:14 +1000, Neil Brown wrote: > On Monday April 28, taeuber@xxxxxxx wrote: > > Hallo Neil, > > > > Neil Brown <neilb@xxxxxxx> schrieb: > > > On Thursday March 13, aia21@xxxxxxxxx wrote: > > > > > > > > Is there a better way to do this? I am hoping someone will tell me to > > > > use option blah to utility foo that will do this for me without having > > > > to break the mirror twice and resync each time. (-; > > > > > > Sorry, but no. This mode of operation was never envisaged for md. > > > I would always put the md/raid1 devices below the LVM. > > > > could you write in some short words what in the design prohibits us to grow a raid1 on a grown lvm? > > By default, the metadata for an md array is stored near the end of > each device. If you make the device larger, you lose the metadata. > This could be address for on-line resizing by having some protocol > whereby the LVM layer tells whoever is using it that it is about to > become larger, so that the metadata can be updated and moved, but that > is probably more hassle than it is worth. > > If you use version 1.1 or 1.2 metadata, the metadata is stored at the > start of the device, so it doesn't get lost. However the metadata has > recorded in it the amount of usable space on the device. When you > make the device bigger you would need to update this number. > There is currently no way to update this for an active array. > > You can stop the array, and the re-assemble it with > --update=devicesize > > this will update the field in the metadata which records the size of > each device. You will then be able to grow the array to make use of > all the space. > > It might not be to hard to make it possible to tell md that devices > have grown.... maybe one day :-) > > NeilBrown I'm concerned, I'm currently planning on swapping two 250GB drives with 750GB drives on a RAID1 array using 2.6.9 RHEL 4.6 (mdadm mdadm-1.12.0). My plan basically was: # remove one small disk /sbin/mdadm /dev/md0 --fail /dev/sdb1 /sbin/mdadm /dev/md0 --remove /dev/sdb1 # shutdown and swap in large disk # (with larger partition for the RAID1 component) # add large drive into array /sbin/mdadm /dev/md0 --add /dev/sdb1 # Allow the array to resync # remove the remaining small drive /sbin/mdadm /dev/md0 --fail /dev/sda1 /sbin/mdadm /dev/md0 --remove /dev/sda1 # Grow the array /sbin/mdadm -G /dev/md0 -z max # shutdown and swap in second large disk # (with larger partition for the RAID1 component) # add in the second large drive /sbin/mdadm /dev/md0 --add /dev/sda1 My concern (based on this discussion) is that this will fail because I am changing the size of the partition underlying the RAID1 array, much like the LVM discussion above, while using ver 0.90 superblock. Do I have a legitimate concern?? Thanks, Russ Hammer -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
