Everyone, I've created a RAID-10 array with mdadm. I created the array using partitions /dev/sd[abcd]1, where the partition starts at sector 2048 and uses the rest of the disk, as specified here: http://www.ibm.com/developerworks/linux/library/l-4kb-sector-disks/index.html#tools IE: 1. fdisk -c -u /dev/sda 2. create partition at 2048 to -0, of type fd 3. repeat for all drives or clone with sfdisk 4. create the array mdadm -A /dev/md0 -v --raid-devices=4 --level=raid10 /dev/sda1 /dev/sdb1 /dev/sdc1 /dev/sdd1 5. add to mdadm.conf mdadm -Es >> /etc/mdadm/mdadm.conf After reboot, the array worked, and I formatted it and started loading it with files. Only later did I realise that at some point (perhaps 2-3 reboots), the partitions were gone, and the array is running on the raw devices: root@venkman:/var/log/cacti# cat /proc/mdstat Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] [raid4] [raid10] md0 : active raid10 sdc[2] sda[0] sdd[3] sdb[1] 3907026944 blocks 64K chunks 2 near-copies [4/4] [UUUU] unused devices: <none> fdisk shows the partition tables are gone too. I found NeilBrown's comment ID #1857419, partway down this page: http://www.issociate.de/board/post/463176/Superblocks.html "If a partition starts a multiple of 64K from the start of the device, and ends with about 64K of the end of the device, then a superblock on the partition will also look like a superblock on the whole device. This is one of the shortcomings of v0.90 superblocks. v1.0 doesn't have this problem." I used mdadm v2.6.7.1, as it comes on Ubuntu 10.10. Is this still a shortcoming of superblock v1.2? Obviously I want to align to the sector size, and use the entire disk. Should I just accept this and not raw devices? Will it happen again if I try to start over? Regards, Tyler -- "If one would give me six lines written by the hand of the most honest man, I would find something in them to have him hanged." -- Armand Jean du Plessis, Cardinal Richelieu -- 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
