On Wednesday June 4, david@xxxxxxxxxxxx wrote: > Jules Bean wrote: > > David Greaves wrote: > > Just add it as a fresh component. The old SB is irrelevant. > > > > 1. Fail component > > 2. remove component > > 3. resize partition > > 4. FORCE KERNEL TO NOTICE NEW SIZE (that's what I got wrong!). Reboot is > > safest. > > 5. add component as new > > > > 6. watch as md layer rebuilds > And that's the bit that shouldn't be needed :) > > Otherwise you're 'just' replacing devices one at a time which isn't very > interesting. > > > Of course this does assume your RAID level has the redundancy required > > to remove a component (i.e. not RAID0). > Neil, would the sb-move approach support RAID0? Maybe. If the old partitions were all exactly the same size, and the new are too. If you start with different sized partitions, md/raid0 uses all the space by having some stripes across fewer devices. So changing the sizes of the partitions will confuse things. > > >> in step 4 mdadm may want to call the reread pt ioctl (which is what > >> blockdev --rereadpt does) > > > > Seems to me that whilst cfdisk makes no visible attempt, plain 'fdisk' > > does try to call this ioctl but nonetheless it doesn't work if some > > other partition on that disk is busy (e.g. involved in some other md > > device, or mounted elsewhere). I saw messages to this effect whilst > > experimenting with different partition sizes looking for my missing > > superblock. > I read (http://linux.derkeiler.com/Mailing-Lists/Kernel/2003-10/4319.html) there > are some ioctls that work even when some disk partitions are still in use > (providing there is no impact). > However I couldn't see them in the block-layer ioctls or any code in > fs/partitions/check.c linux/block/ioctl.c. BLKPG_DEL_PARTITION BLKPG_ADD_PARTITION Only works if the partition being changed isn't in used though. NeilBrown -- 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
