Hi I have a 4-disk RAID10 array md0 : active raid10 sda1[4] sdb1[3] sdc1[2] sdd1[1] 1953259520 blocks super 1.2 512K chunks 2 far-copies [4/4] [UUUU] bitmap: 0/15 pages [0KB], 65536KB chunk It was created with this command mdadm --create /dev/md0 --level=raid10 --raid-devices=4 \ --name=md0 --homehost="<none>" \ --metadata=1.2 --bitmap=internal --layout=f2 --chunk=512 \ /dev/sd[abcd]1 It's running on a linux machine uname -rm 4.8.1-2.g4861355-default x86_64 mdadm --version mdadm - v3.3.1 - 5th June 2014 I need to add storage to the array. I'd like to grow it by adding two disks (/dev/sd[ef]), to end up with a 6-disk array. I know I can completely wipe it out and recreate it with 6-disks. But I'd rather grow/extend it, Instead. *CAN* I safely grow/expand it? The ChangeLog for mdadm 3.3.1 says Changes Prior to release 3.3 - Some array reshapes can proceed without needing backup file. This is done by changing the 'data_offset' so we never need to write any data back over where it was before. If there is no "head space" or "tail space" to allow data_offset to change, the old mechanism with a backup file can still be used. - RAID10 arrays can be reshaped to change the number of devices, change the chunk size, or change the layout between 'near' and 'offset'. This will always change data_offset, and will fail if there is no room for data_offset to be moved. So far I haven't found any specific "how to" for this process. (1) The changelog refers to 'near' and 'offset' layouts, but doesn't mention 'far'. CAN I safely grow this layout=f2 array ? (2) If I can, what's the detailed procedure to do it? Thanks Mike -- 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
