Hi Neil/Chris, I ran into a similar situation as described in your thread (ack in Jun 2008): http://marc.info/?l=linux-raid&m=121381509915920&w=2 First off, thank you both for your time to make this feature work. Since I've increased the partition size of my RAID partition, I too needed to grow my array and component devices. To do that, I attempted to use the feature implemented in this patch: http://marc.info/?l=linux-raid&m=121434960912711&w=2 However, it seems that the value applied by this method is half the actual/correct value. For example: Before Change: # mdadm --examine /dev/sda2 <snip> Avail Dev Size : 41495751 (19.79 GiB 21.25 GB) Array Size : 41495751 (19.79 GiB 21.25 GB) # cat /sys/block/md127/md/dev-sda2/size 20747875 The size here is in 1K blocks (also consistent with the documentation in md.txt). After Change: # echo "0" > /sys/block/md127/md/dev-sda2/size # cat /sys/block/md127/md/dev-sda2/size 121889135 # mdadm --examine /dev/sda2 <snip> Avail Dev Size : 487556541 (232.49 GiB 249.63 GB) Array Size : 41495751 (19.79 GiB 21.25 GB) Used Dev Size : 41495751 (19.79 GiB 21.25 GB) When attempting to grow the array, it's capped to the value stored in the component device's size: # mdadm --grow /dev/md127 --size=max mdadm: component size of /dev/md127 has been set to 121889135K # mdadm --examine /dev/sda2 <snip> Avail Dev Size : 487556541 (232.49 GiB 249.63 GB) Array Size : 243778270 (116.24 GiB 124.81 GB) Used Dev Size : 243778270 (116.24 GiB 124.81 GB) Here is the partition table: Device Boot Start End Blocks Id System /dev/sda1 1 33 265041 fd Linux raid autodetect /dev/sda2 34 30382 243778342+ fd Linux raid autodetect The bright side is that a reboot fixes the problem. After reboot, all the values show up correctly: # cat /sys/block/md127/md/dev-sda2/size 243778270 # mdadm --grow /dev/md127 --size=max mdadm: component size of /dev/md127 has been set to 243778270K With that in place, it seems that this is a very minor bug. However, it does prevent one from doing everything online (I assume that was the original intent of this feature/patch). Skimming at the code, it seems that the correct value is written to the superblock, but the value returned is divided 2. Per the comments, it seems that is what gets set to in sysfs. If on boot it reads the superblock, that may explain why it self-corrects. (Didn't dig too much into the code, so this is a hypothesis). Anyways, my problem is resolved by a reboot. Just want to pass this along so others don't spend time figuring this out. Thanks, Martin -- 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
