On Thu, 11 Dec 2014 19:21:39 +0000 Robin Hill <robin@xxxxxxxxxxxxxxx> wrote: > On Thu Dec 11, 2014 at 07:31:31PM +0100, cvb@xxxxxxxxxxx wrote: > > > Apologies for raising this topic again, but I can't seem to find > > anything googling, and man mdadm doesn't also give me a clue. Which > > kernel version is needed to grow a near-2 RAID 10 array? > > > Full reshape support (changing number of devices, layout or chunk size) > was introduced in 3.5 (http://kernelnewbies.org/Linux_3.5). > > > I'm currently running kernel 3.13.0 with mdadm 3.2.5. But I could also > > use a live CD with a newer kernel, if needed. > > > It also requires mdadm 3.3 or above. > > > I have replaced the 4 disks here with larger ones (2TB drives -> 4 TB > > drives), and this is what the array currently looks like: > > > > # mdadm --detail /dev/md0 > > /dev/md0: > > Version : 1.2 > > Creation Time : Sat Aug 20 08:15:07 2011 > > Raid Level : raid10 > > Array Size : 3906764800 (3725.78 GiB 4000.53 GB) > > Used Dev Size : 1953382400 (1862.89 GiB 2000.26 GB) > > Raid Devices : 4 > > Total Devices : 4 > > Persistence : Superblock is persistent > > > > Update Time : Thu Dec 11 08:31:15 2014 > > State : clean > > Active Devices : 4 > > Working Devices : 4 > > Failed Devices : 0 > > Spare Devices : 0 > > > > Layout : near=2 > > Chunk Size : 512K > > > > Name : alpha:0 (local to host alpha) > > UUID : 8199e640:58fc3a04:99b52fe6:80a1574d > > Events : 918971 > > > > Number Major Minor RaidDevice State > > 6 8 1 0 active sync /dev/sda1 > > 5 8 33 1 active sync /dev/sdc1 > > 7 8 17 2 active sync /dev/sdb1 > > 4 8 49 3 active sync /dev/sdd1 > > > I can't find anything explicitly covering growing a RAID 10 by just > increasing the device sizes. commit 006a09a0ae0a494473a8cd82c8d1d653e37e6663 Author: NeilBrown <neilb@xxxxxxx> Date: Mon Mar 19 12:46:40 2012 +1100 md/raid10 - support resizing some RAID10 arrays. $ git describe --contains 006a09a0ae0a494473a8cd82c8d1d653e37e6663 v3.4-rc1~147^2~8 So Linux-3.4 is needed. I don't think you need a particularly new mdadm. NeilBrown > I would have thought that would be an > easier task than doing so by adding disks, so should be supported in an > earlier version. mdadm 3.2.1 mentions supporting converting between > RAID-10 and RAID-1, which can definitely be grown. > > Have you tried doing a grow with the versions you have? > > Cheers, > Robin >
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