I had an AXS-6320 storage array with 8 1Tb HDD (RAID5). It suddenly stopped to recornize the array and sees only bare drives. I am afraid that making one from scratch should cause it to zeroize all data. (There are, of course, recovery option in it's management console, but it did not produce any positive results).
I installed all 8 HDD to a linux PC. They are sda to sdh. Not there are a problem: that system does NOT have a superblock of any recognizable format.
root@PartedMagic:~# mdadm --examine -e imsm /dev/sda mdadm: no IMSM anchor on /dev/sda mdadm: Failed to load all information sections on /dev/sda root@PartedMagic:~# mdadm --examine -e ddf /dev/sda mdadm: no DDF anchor found on /dev/sda root@PartedMagic:~# mdadm --examine -e 1 /dev/sda mdadm: No super block found on /dev/sda (Expected magic a92b4efc, got 00000000) mdadm: No super block found on /dev/sda (Expected magic a92b4efc, got d08ec033) mdadm: No super block found on /dev/sda (Expected magic a92b4efc, got 00000000) What is has, is:
root@PartedMagic:~# dd if=/dev/sda skip=1 count=1 |hexdump -C 00000000 24 52 61 69 64 53 44 24 08 00 00 00 08 00 00 00 |$RaidSD$........| 00000010 0a 5f 0e 03 f6 b2 f6 b2 f6 b2 f6 b2 f6 b2 f6 b2 |._..............| 00000020 f6 b2 f6 b2 00 00 00 00 00 00 00 00 00 00 00 00 |................| 00000030 00 00 00 00 09 23 0e 2a 13 2c 0a 23 11 23 13 28 |.....#.*.,.#.#.(| 00000040 0a 1f 0a 1e 00 00 00 00 00 00 00 00 00 00 00 00 |................| 00000050 00 00 00 00 00 00 00 00 02 00 00 00 00 00 00 00 |................| 00000060 00 54 6a 74 00 00 00 00 52 61 69 64 20 53 65 74 |.Tjt....Raid Set| 00000070 20 23 20 30 30 20 20 20 00 00 00 00 00 00 00 00 | # 00 ........| 00000080 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................| --- root@PartedMagic:~# dd if=/dev/sdh skip=1 count=1 |hexdump -C 00000000 24 52 61 69 64 53 44 24 08 00 00 00 08 00 00 00 |$RaidSD$........| 00000010 ce 01 00 00 00 00 f6 b2 f6 b2 f6 b2 f6 b2 f6 b2 |................| 00000020 f6 b2 f6 b2 00 00 00 00 00 00 00 00 00 00 00 00 |................| 00000030 00 00 00 00 00 00 0e 2a 13 2c 0a 23 11 23 13 28 |.......*.,.#.#.(| 00000040 0a 1f 0a 1e 00 00 00 00 00 00 00 00 00 00 00 00 |................| 00000050 00 00 00 00 07 00 00 00 02 00 00 00 02 00 00 00 |................| 00000060 00 54 6a 74 00 00 00 00 52 61 69 64 20 53 65 74 |.Tjt....Raid Set| 00000070 20 23 20 30 30 20 20 20 00 00 00 00 00 00 00 00 | # 00 ........| 00000080 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................| seems, 0[8] is the signature, x08[4] is number of disks x10[4] is some sort of serial x54[4] is the disk id
scanning the disk further, I found the actual partition sector at offset x41000
root@PartedMagic:~# dd if=/dev/sda skip=520 count=1 |hexdump -C 00000000 33 c0 8e d0 bc 00 7c 8e c0 8e d8 be 00 7c bf 00 |3.....|......|..| 00000010 06 b9 00 02 fc f3 a4 50 68 1c 06 cb fb b9 04 00 |.......Ph.......| 00000020 bd be 07 80 7e 00 00 7c 0b 0f 85 0e 01 83 c5 10 |....~..|........| 00000030 e2 f1 cd 18 88 56 00 55 c6 46 11 05 c6 46 10 00 |.....V.U.F...F..| 00000040 b4 41 bb aa 55 cd 13 5d 72 0f 81 fb 55 aa 75 09 |.A..U..]r...U.u.| 00000050 f7 c1 01 00 74 03 fe 46 10 66 60 80 7e 10 00 74 |....t..F.f`.~..t| 00000060 26 66 68 00 00 00 00 66 ff 76 08 68 00 00 68 00 |&fh....f.v.h..h.| 00000070 7c 68 01 00 68 10 00 b4 42 8a 56 00 8b f4 cd 13 ||h..h...B.V.....| 00000080 9f 83 c4 10 9e eb 14 b8 01 02 bb 00 7c 8a 56 00 |............|.V.| 00000090 8a 76 01 8a 4e 02 8a 6e 03 cd 13 66 61 73 1c fe |.v..N..n...fas..| 000000a0 4e 11 75 0c 80 7e 00 80 0f 84 8a 00 b2 80 eb 84 |N.u..~..........| 000000b0 55 32 e4 8a 56 00 cd 13 5d eb 9e 81 3e fe 7d 55 |U2..V...]...>.}U| 000000c0 aa 75 6e ff 76 00 e8 8d 00 75 17 fa b0 d1 e6 64 |.un.v....u.....d| 000000d0 e8 83 00 b0 df e6 60 e8 7c 00 b0 ff e6 64 e8 75 |......`.|....d.u| 000000e0 00 fb b8 00 bb cd 1a 66 23 c0 75 3b 66 81 fb 54 |.......f#.u;f..T| 000000f0 43 50 41 75 32 81 f9 02 01 72 2c 66 68 07 bb 00 |CPAu2....r,fh...| 00000100 00 66 68 00 02 00 00 66 68 08 00 00 00 66 53 66 |.fh....fh....fSf| 00000110 53 66 55 66 68 00 00 00 00 66 68 00 7c 00 00 66 |SfUfh....fh.|..f| 00000120 61 68 00 00 07 cd 1a 5a 32 f6 ea 00 7c 00 00 cd |ah.....Z2...|...| 00000130 18 a0 b7 07 eb 08 a0 b6 07 eb 03 a0 b5 07 32 e4 |..............2.| 00000140 05 00 07 8b f0 ac 3c 00 74 09 bb 07 00 b4 0e cd |......<.t.......| 00000150 10 eb f2 f4 eb fd 2b c9 e4 64 eb 00 24 02 e0 f8 |......+..d..$...| 00000160 24 02 c3 49 6e 76 61 6c 69 64 20 70 61 72 74 69 |$..Invalid parti| 00000170 74 69 6f 6e 20 74 61 62 6c 65 00 45 72 72 6f 72 |tion table.Error| 00000180 20 6c 6f 61 64 69 6e 67 20 6f 70 65 72 61 74 69 | loading operati| 00000190 6e 67 20 73 79 73 74 65 6d 00 4d 69 73 73 69 6e |ng system.Missin| 000001a0 67 20 6f 70 65 72 61 74 69 6e 67 20 73 79 73 74 |g operating syst| 000001b0 65 6d 00 00 00 63 7b 9a 00 00 00 00 00 00 00 00 |em...c{.........| 000001c0 02 00 ee ff ff ff 01 00 00 00 ff ff ff ff 00 00 |................| 000001d0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................| * 000001f0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 55 aa |..............U.| sdb-sdg corresponding sectors are zeroes, ans sdh contained the exact copy of sda, so I assume it is csum, and it is "ra" style. From other alike controller, I suppose that stripe size is 64k, but of course is could be checked.
As I see, mdadm --build can only build RAID0-1 arrays, are there some driver to make a raid5 manually WITHOUT trying to recover/fix anything or create metadata, just read sectors and maybe signal "BAD" in case of checksum error?