Hi (please reply-all) I've a RAID6 array (sda sdb sdd sde sdf1) that I can't assemble under Arch, but it worked fine under Ubuntu. mdadm - v3.3.4 - 3rd August 2015, kernel 4.1.6 Here is the mdadm --examine for each drive: [root@ion ~]# mdadm --examine /dev/sda /dev/sda: Magic : a92b4efc Version : 1.2 Feature Map : 0x0 Array UUID : 0ad2603e:e43283ee:02180773:98e716ef Name : ion:md0 (local to host ion) Creation Time : Tue Feb 5 17:33:27 2013 Raid Level : raid6 Raid Devices : 6 Avail Dev Size : 3906767024 (1862.89 GiB 2000.26 GB) Array Size : 7813531648 (7451.56 GiB 8001.06 GB) Used Dev Size : 3906765824 (1862.89 GiB 2000.26 GB) Data Offset : 262144 sectors Super Offset : 8 sectors Unused Space : before=262064 sectors, after=18446744073706818560 sectors State : clean Device UUID : a09fc60d:5c4a27a5:4b89bc33:29b01582 Update Time : Tue Nov 4 21:43:49 2014 Checksum : 528563ee - correct Events : 97557 Layout : left-symmetric Chunk Size : 512K Device Role : Active device 3 Array State : AA.AAA ('A' == active, '.' == missing, 'R' == replacing) [root@ion ~]# mdadm --examine /dev/sdb /dev/sdb: Magic : a92b4efc Version : 1.2 Feature Map : 0x0 Array UUID : 0ad2603e:e43283ee:02180773:98e716ef Name : ion:md0 (local to host ion) Creation Time : Tue Feb 5 17:33:27 2013 Raid Level : raid6 Raid Devices : 6 Avail Dev Size : 3906767024 (1862.89 GiB 2000.26 GB) Array Size : 7813531648 (7451.56 GiB 8001.06 GB) Used Dev Size : 3906765824 (1862.89 GiB 2000.26 GB) Data Offset : 262144 sectors Super Offset : 8 sectors Unused Space : before=262064 sectors, after=18446744073706818560 sectors State : clean Device UUID : 93568b01:632395bf:7d0082a5:db9b6ff9 Update Time : Tue Nov 4 21:43:49 2014 Checksum : 49d756ca - correct Events : 97557 Layout : left-symmetric Chunk Size : 512K Device Role : Active device 0 Array State : AA.AAA ('A' == active, '.' == missing, 'R' == replacing) [root@ion ~]# mdadm --examine /dev/sdd /dev/sdd: Magic : a92b4efc Version : 1.2 Feature Map : 0x0 Array UUID : 0ad2603e:e43283ee:02180773:98e716ef Name : ion:md0 (local to host ion) Creation Time : Tue Feb 5 17:33:27 2013 Raid Level : raid6 Raid Devices : 6 Avail Dev Size : 3906767024 (1862.89 GiB 2000.26 GB) Array Size : 7813531648 (7451.56 GiB 8001.06 GB) Used Dev Size : 3906765824 (1862.89 GiB 2000.26 GB) Data Offset : 262144 sectors Super Offset : 8 sectors Unused Space : before=262064 sectors, after=1200 sectors State : clean Device UUID : 78df2586:cb5649aa:e0b6d211:d92dc224 Update Time : Tue Nov 4 21:43:49 2014 Checksum : 50c95b7c - correct Events : 97557 Layout : left-symmetric Chunk Size : 512K Device Role : Active device 5 Array State : AA.AAA ('A' == active, '.' == missing, 'R' == replacing) [root@ion ~]# mdadm --examine /dev/sde /dev/sde: Magic : a92b4efc Version : 1.2 Feature Map : 0x0 Array UUID : 0ad2603e:e43283ee:02180773:98e716ef Name : ion:md0 (local to host ion) Creation Time : Tue Feb 5 17:33:27 2013 Raid Level : raid6 Raid Devices : 6 Avail Dev Size : 3906767024 (1862.89 GiB 2000.26 GB) Array Size : 7813531648 (7451.56 GiB 8001.06 GB) Used Dev Size : 3906765824 (1862.89 GiB 2000.26 GB) Data Offset : 262144 sectors Super Offset : 8 sectors Unused Space : before=262064 sectors, after=1200 sectors State : clean Device UUID : 41712f8c:255b0f3e:0e345f7b:e1504e42 Update Time : Tue Nov 4 21:43:49 2014 Checksum : 71b191d6 - correct Events : 97557 Layout : left-symmetric Chunk Size : 512K Device Role : Active device 1 Array State : AA.AAA ('A' == active, '.' == missing, 'R' == replacing) [root@ion ~]# mdadm --examine /dev/sdf1 /dev/sdf1: Magic : a92b4efc Version : 1.2 Feature Map : 0x1 Array UUID : 4cae433f:a40afcf5:f9aba91d:d8217b69 Name : ion:0 (local to host ion) Creation Time : Thu Nov 20 23:52:58 2014 Raid Level : raid6 Raid Devices : 5 Avail Dev Size : 3904030720 (1861.59 GiB 1998.86 GB) Array Size : 5856046080 (5584.76 GiB 5996.59 GB) Data Offset : 262144 sectors Super Offset : 8 sectors Unused Space : before=262056 sectors, after=0 sectors State : clean Device UUID : eaa0dcba:d04a7c16:6c256916:67a491ae Internal Bitmap : 8 sectors from superblock Update Time : Sun Sep 20 19:47:50 2015 Bad Block Log : 512 entries available at offset 72 sectors Checksum : b1f6f725 - correct Events : 59736 Layout : left-symmetric Chunk Size : 512K Device Role : Active device 3 Array State : AAAAA ('A' == active, '.' == missing, 'R' == replacing) Here is ldrv: [root@ion ~]# python2 lsdrv PCI [megaraid_sas] 02:0e.0 RAID bus controller: LSI Logic / Symbios Logic MegaRAID SAS 1068 ├scsi 0:2:0:0 LSI MegaRAID 84016E {00ede206d4a731011c50ff5e02b00506} │└sda 1.82t [8:0] MD raid6 (6) inactive 'ion:md0' {0ad2603e-e432-83ee-0218-077398e716ef} └scsi 0:2:1:0 LSI MegaRAID 84016E {0036936cc4270000ff50ff5e02b00506} └sdb 1.82t [8:16] MD raid6 (6) inactive 'ion:md0' {0ad2603e-e432-83ee-0218-077398e716ef} PCI [ahci] 00:1f.2 SATA controller: Intel Corporation 8 Series/C220 Series Chipset Family 6-port SATA Controller 1 [AHCI mode] (rev 05) ├scsi 1:0:0:0 ATA INTEL SSDSA2BW16 {BTPR2062006T160DGN} │└sdc 149.05g [8:32] Partitioned (dos) │ ├sdc1 256.00m [8:33] ext4 'boot' {f7727d21-646d-42f9-844b-50591b7f8358} │ │└Mounted as /dev/sdc1 @ /boot │ └sdc2 140.00g [8:34] PV LVM2_member 40.00g used, 100.00g free {KGQ5TJ-mVvL-1Ccd-CKae-1QvS-6AFn-8jFQAw} │ └VG ArchVG 140.00g 100.00g free {F2vaKY-XO4m-UEih-f9Fh-sHgX-cRsN-SLi3Oo} │ ├dm-1 32.00g [254:1] LV root ext4 'root' {82fa2951-25c8-4e36-bf36-9f4f7747ac46} │ │└Mounted as /dev/mapper/ArchVG-root @ / │ └dm-0 8.00g [254:0] LV swap swap {0e3f4596-fa50-4fed-875f-f8427084d9b5} ├scsi 2:0:0:0 ATA SAMSUNG HD204UI {S2H7JR0B501861} │└sdd 1.82t [8:48] MD raid6 (6) inactive 'ion:md0' {0ad2603e-e432-83ee-0218-077398e716ef} ├scsi 3:x:x:x [Empty] ├scsi 4:x:x:x [Empty] ├scsi 5:0:0:0 ATA WDC WD20EARS-00J {WD-WCAWZ2036074} │└sde 1.82t [8:64] MD raid6 (6) inactive 'ion:md0' {0ad2603e-e432-83ee-0218-077398e716ef} └scsi 6:0:0:0 ATA ST3000DM001-1CH1 {W1F2PZGH} └sdf 2.73t [8:80] Partitioned (dos) ├sdf1 1.82t [8:81] MD raid6 (5) inactive 'ion:0' {4cae433f-a40a-fcf5-f9ab-a91dd8217b69} ├sdf2 1.30g [8:82] MD raid0 (3) inactive 'ion:1' {a20b70d4-7ee1-7e3f-abab-74f8dadb8cd8} └sdf3 184.98g [8:83] ext4 '198GB' {e4fc427a-4ec1-48dc-8d9b-bfcffe06d42f} If I try: [root@ion ~]# mdadm --assemble --scan mdadm: /dev/md/0 assembled from 1 drive - not enough to start the array. mdadm: /dev/md/1 assembled from 1 drive - not enough to start the array. >From dmesg: [ 1227.671344] sda: sda1 [ 1227.680392] md: sda does not have a valid v1.2 superblock, not importing! [ 1227.680414] md: md_import_device returned -22 [ 1227.680462] md: md0 stopped. [ 1227.707969] sdb: sdb1 [ 1227.718598] md: sdb does not have a valid v1.2 superblock, not importing! [ 1227.718611] md: md_import_device returned -22 [ 1227.718631] md: md0 stopped. [ 1286.334542] md: md0 stopped. [ 1286.338250] md: bind<sdf1> [ 1286.338390] md: md0 stopped. [ 1286.338400] md: unbind<sdf1> [ 1286.348350] md: export_rdev(sdf1) [ 1286.372268] md: bind<sdf1> [ 1286.373390] md: md1 stopped. [ 1286.373936] md: bind<sdf2> [ 1286.373977] md: md1 stopped. [ 1286.373983] md: unbind<sdf2> [ 1286.388061] md: export_rdev(sdf2) [ 1286.405140] md: bind<sdf2> [root@ion ~]# cat /proc/mdstat Personalities : md1 : inactive sdf2[2](S) 1366104 blocks super 1.2 md0 : inactive sdf1[3](S) 1952015360 blocks super 1.2 unused devices: <none> If I try manually (I'm not sure of the order though): [root@ion ~]# mdadm --assemble --readonly --verbose /dev/md0 /dev/sda /dev/sdb /dev/sdd /dev/sde mdadm: looking for devices for /dev/md0 mdadm: /dev/sda is identified as a member of /dev/md0, slot 3. mdadm: /dev/sdb is identified as a member of /dev/md0, slot 0. mdadm: /dev/sdd is identified as a member of /dev/md0, slot 5. mdadm: /dev/sde is identified as a member of /dev/md0, slot 1. mdadm: added /dev/sde to /dev/md0 as 1 mdadm: no uptodate device for slot 2 of /dev/md0 mdadm: failed to add /dev/sda to /dev/md0: Invalid argument mdadm: no uptodate device for slot 4 of /dev/md0 mdadm: added /dev/sdd to /dev/md0 as 5 mdadm: failed to add /dev/sdb to /dev/md0: Invalid argument mdadm: /dev/md0 assembled from 2 drives - need 5 to start (use --run to insist). Any idea where I should start? Thanks Mathias -- 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