Hello, After having problem with detecting RAID arrays on my computer and discussions on IRC, I came across a problem in RAID detection in GRUB2 in certain condition. Details of my current setup at the bottom of this message. In my setup my 4 disks are partionned using GPT, 320GB each with a protective 0xEE GPT partition. Partition 1 on each disk is 0xEF02 for GRUB offsetted at sector 2048. Partition 2 are 0xFD00 RAID1 with 4 members for /boot Partition 3 are 0xFD00 RAID5 with 4 members formatted as LVM and takes the rest of the disk, which means it includes the last available non-GPT sector. Both RAIDs have metadata format 0.9. When GRUB detects RAID1, I get (md0) which is OK, but when it detects the RAID5, it detects the RAID as starting from sector 0 of the disk as it checks the disk instead of the GPT partition but still cuts the length as in the superblock, so I get (md1,gpt[1,2,3]) and (md1,gpt3) does not show correctly else LVM would detect it anyway (I guess). So options presented to us to fix are: 1. Check for RAID in partitions first, then in whole disk. 2. Verify minor number in superblock to see if they are divisible per 16 which would mean it is whole disk, however I guess this is SCSI/SATA-centric. 3. What I currently implemented because I didn't know GRUB2 better, compare size in superblock vs size of the currently probed device plus a margin to see if content fits with superblock. I know I could have fixed this by reducing my last GPT partition a bit, but I guess other people will fall in this problem sometime when bigger disk start using GPT, anyway, maybe metadata 0.9 will start disappearing afterward. Notice how sda and sda3 are the same. md0 : active raid1 sdc2[0] sdd2[3] sda2[2] sdb2[1] 524224 blocks [4/4] [UUUU] bitmap: 0/64 pages [0KB], 4KB chunk md1 : active raid5 sdd3[0] sda3[3] sdc3[2] sdb3[1] 936115200 blocks level 5, 64k chunk, algorithm 2 [4/4] [UUUU] bitmap: 4/149 pages [16KB], 1024KB chunk mdadm -E /dev/sda /dev/sda: Magic : a92b4efc Version : 0.90.00 UUID : cdf20521:cfed4cc3:130ede86:cb56fef4 Creation Time : Sun May 17 16:53:26 2009 Raid Level : raid5 Used Dev Size : 312038400 (297.58 GiB 319.53 GB) Array Size : 936115200 (892.75 GiB 958.58 GB) Raid Devices : 4 Total Devices : 4 Preferred Minor : 1 Update Time : Mon Jan 10 15:37:30 2011 State : clean Internal Bitmap : present Active Devices : 4 Working Devices : 4 Failed Devices : 0 Spare Devices : 0 Checksum : cfb6f02f - correct Events : 3676708 Layout : left-symmetric Chunk Size : 64K Number Major Minor RaidDevice State this 3 8 3 3 active sync /dev/sda3 0 0 8 51 0 active sync /dev/sdd3 1 1 8 19 1 active sync /dev/sdb3 2 2 8 35 2 active sync /dev/sdc3 3 3 8 3 3 active sync /dev/sda3 p4 ~ # mdadm -E /dev/sda3 /dev/sda3: Magic : a92b4efc Version : 0.90.00 UUID : cdf20521:cfed4cc3:130ede86:cb56fef4 Creation Time : Sun May 17 16:53:26 2009 Raid Level : raid5 Used Dev Size : 312038400 (297.58 GiB 319.53 GB) Array Size : 936115200 (892.75 GiB 958.58 GB) Raid Devices : 4 Total Devices : 4 Preferred Minor : 1 Update Time : Mon Jan 10 15:37:30 2011 State : clean Internal Bitmap : present Active Devices : 4 Working Devices : 4 Failed Devices : 0 Spare Devices : 0 Checksum : cfb6f02f - correct Events : 3676708 Layout : left-symmetric Chunk Size : 64K Number Major Minor RaidDevice State this 3 8 3 3 active sync /dev/sda3 0 0 8 51 0 active sync /dev/sdd3 1 1 8 19 1 active sync /dev/sdb3 2 2 8 35 2 active sync /dev/sdc3 3 3 8 3 3 active sync /dev/sda3 p4 ~ # gdisk -l /dev/sda GPT fdisk (gdisk) version 0.6.9 Partition table scan: MBR: protective BSD: not present APM: not present GPT: present Found valid GPT with protective MBR; using GPT. Disk /dev/sda: 625142448 sectors, 298.1 GiB Logical sector size: 512 bytes Disk identifier (GUID): 24746079-21E4-4960-B9B5-479955CC7462 Partition table holds up to 128 entries First usable sector is 34, last usable sector is 625142414 Partitions will be aligned on 2048-sector boundaries Total free space is 2014 sectors (1007.0 KiB) Number Start (sector) End (sector) Size Code Name 1 2048 4095 1024.0 KiB EF02 GRUB2 2 4096 1052671 512.0 MiB FD00 RAID1 Boot 3 1052672 625142414 297.6 GiB FD00 RAID5 LVM p4 ~ # fdisk -luc /dev/sda Disk /dev/sda: 320.1 GB, 320072933376 bytes 256 heads, 63 sectors/track, 38761 cylinders, total 625142448 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00000000 Device Boot Start End Blocks Id System /dev/sda1 1 625142447 312571223+ ee GPT -- 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
