On 10/26/2012 04:31 PM, John Drescher wrote: > I got the following message when trying to convert a 2 disk raid1 to a > 6 disk raid 6 in a 3.3.8 kernel: > > fileserver1 btrfs-root # mdadm --grow /dev/md3 --level=6 --raid-devices=6 > mdadm: Cannot convert RAID1 of this size - reduce size to multiple of 4K first. > > Fileserver1 btrfs-root # uname -a > Linux fileserver1 3.3.8-gentoo-fileserver1-raid1 #3 SMP Thu Jul 12 > 20:06:18 EDT 2012 x86_64 Intel(R) Xeon(R) CPU E31230 @ 3.20GHz > GenuineIntel GNU/Linux > > fileserver1 btrfs-root # mdadm --version > mdadm - v3.2.6 - 25th October 2012 > > fileserver1 btrfs-root # mdadm -D /dev/md3 > /dev/md3: > Version : 1.2 > Creation Time : Wed Sep 28 16:03:56 2011 > Raid Level : raid1 > Array Size : 1874607039 (1787.76 GiB 1919.60 GB) > Used Dev Size : 1874607039 (1787.76 GiB 1919.60 GB) > Raid Devices : 2 > Total Devices : 6 > Persistence : Superblock is persistent > > Update Time : Fri Oct 26 16:24:22 2012 > State : clean > Active Devices : 2 > Working Devices : 6 > Failed Devices : 0 > Spare Devices : 4 > > Name : fileserver1:3 (local to host fileserver1) > UUID : df2200d4:3ba5d29c:524dc437:35d663ea > Events : 785 > > Number Major Minor RaidDevice State > 0 8 116 0 active sync /dev/sdh4 > 1 8 4 1 active sync /dev/sda4 > > 2 8 244 - spare /dev/sdp4 > 3 8 196 - spare /dev/sdm4 > 4 8 212 - spare /dev/sdn4 > 5 8 228 - spare /dev/sdo4 The "Used Dev Size" must be a multiple of the target chunk size, and the smallest allowed chunk size is 4K. > Would upgrading the kernel avoid needing to reduce the size of the > array? If not I assume I have to reduce the size of the btrfs > filesystem then resize the array to 1874604032. Is that correct? Upgrading the kernel won't help. For a 4K chunk size, 1874607032 sectors is correct. For other chunk sizes, you'll have to shrink a bit more (1874607039 == 0x6FBC3BBF). HTH, Phil -- 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
