# tr '\0' '\377' < /dev/zero > /dev/VG/1 ## then used gdisk to create new GPT and a single partition # hexdump -C /dev/VG/1 [root@f24s ~]# hexdump -C /dev/VG/1 00000000 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff |................| * 000001b0 ff ff ff ff ff ff ff ff 00 00 00 00 00 00 00 fe |................| 000001c0 ff ff ee ff ff ff 01 00 00 00 ff ff 9f 00 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.| 00000200 45 46 49 20 50 41 52 54 00 00 01 00 5c 00 00 00 |EFI PART....\...| 00000210 6d c0 57 bd 00 00 00 00 01 00 00 00 00 00 00 00 |m.W.............| 00000220 ff ff 9f 00 00 00 00 00 22 00 00 00 00 00 00 00 |........".......| 00000230 de ff 9f 00 00 00 00 00 dc 74 3e 4a 76 e2 b6 44 |.........t>Jv..D| 00000240 8d 30 bd d8 07 62 45 f8 02 00 00 00 00 00 00 00 |.0...bE.........| 00000250 80 00 00 00 80 00 00 00 3f d0 39 d5 00 00 00 00 |........?.9.....| 00000260 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................| * 00000400 0f 88 9d a1 fc 05 3b 4d a0 06 74 3f 0f 84 91 1e |......;M..t?....| 00000410 b9 3b b1 50 5f 9f 80 47 a7 82 44 cc 2b 52 56 98 |.;.P_..G..D.+RV.| 00000420 00 08 00 00 00 00 00 00 de ff 9f 00 00 00 00 00 |................| 00000430 00 00 00 00 00 00 00 00 4c 00 69 00 6e 00 75 00 |........L.i.n.u.| 00000440 78 00 20 00 52 00 41 00 49 00 44 00 00 00 00 00 |x. .R.A.I.D.....| 00000450 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................| * 00004400 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff |................| * ^C And then wiping with 1's again, mdadm -C with default v1.2 metadata on the whole device. 00000000 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff |................| * 00001000 fc 4e 2b a9 01 00 00 00 00 00 00 00 00 00 00 00 |.N+.............| 00001010 f9 b7 39 86 d6 37 9b c4 04 b8 f2 a8 91 ef 8b 8b |..9..7..........| 00001020 66 32 34 73 3a 30 00 00 00 00 00 00 00 00 00 00 |f24s:0..........| 00001030 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................| 00001040 3a 85 97 57 00 00 00 00 01 00 00 00 00 00 00 00 |:..W............| 00001050 00 e0 9f 00 00 00 00 00 00 00 00 00 02 00 00 00 |................| 00001060 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................| * 00001080 00 20 00 00 00 00 00 00 00 e0 9f 00 00 00 00 00 |. ..............| 00001090 08 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................| 000010a0 00 00 00 00 00 00 00 00 8d 69 45 42 e9 a4 ad c2 |.........iEB....| 000010b0 c1 b1 f8 8c d5 8d 7e 22 00 00 08 00 48 00 00 00 |......~"....H...| 000010c0 43 85 97 57 00 00 00 00 04 00 00 00 00 00 00 00 |C..W............| 000010d0 00 4b 07 00 00 00 00 00 28 cd 5d 00 80 00 00 00 |.K......(.].....| 000010e0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................| * 00001100 00 00 01 00 fe ff fe ff fe ff fe ff fe ff fe ff |................| 00001110 fe ff fe ff fe ff fe ff fe ff fe ff fe ff fe ff |................| * 00001200 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff |................| * ^C So yeah, if gdisk is used first, then mdadm second, and mdadm is pointed to the whole block device rather than a partition, mdadm does not step on any part of the GPT. Therefore something else hit LBA 1 in the OP's case (I previously said LBA 2, that's a typo, the header is on LBA 1 at least on 512 byte logical sector drives). Maybe it's a rare case of silent data corruption on that sector? However, it does appear that in the OP's case that the array was created on the whole disk device, not on the partition. If true, I would remove the signatures on the GPT primary and secondary headers to make sure they're invalidated. Otherwise it's ambiguous what these drives are all about, are they single partition drives that are empty? Or are they whole device md members? I'd look at using wipefs -b -t or -o to remove the GPT signatures, while avoiding the mdadm and file system signatures. Chris Murphy -- 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
