root@jackie:/home/rj# /sbin/fdisk -l /dev/sdb Disk /dev/sdb: 2.73 TiB, 3000592982016 bytes, 5860533168 sectors Disk model: Hitachi HUS72403 Units: sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 4096 bytes I/O size (minimum/optimal): 4096 bytes / 4096 bytes Disklabel type: gpt Disk identifier: AF5DC5DE-1404-4F4F-85AF-B5574CD9C627 Device Start End Sectors Size Type /dev/sdb1 2048 5860532223 5860530176 2.7T Microsoft basic data root@jackie:/home/rj# cat /sys/block/sdb/sdb1/start 2048 root@jackie:/home/rj# cat /sys/block/sdb/sdb1/size 5860530176 (I haven't checked all of the drives in the array, just this one.) Thanks. --RJ On Thursday, January 25, 2024 at 06:07:27 AM EST, Pascal Hambourg <pascal@xxxxxxxxxxxxxxx> wrote: On 25/01/2024 at 02:57, Roger Heflin wrote: > > dd if=/dev/zero of=/dev/sdb bs=512 count=1 (for each disk). I'm afraid it won't help. As far as I can see, having an MBR signature in the first sector does not prevent blkid or mdadm from detecting the RAID superblock. Also, previous mail from the OP show that the disks have GPT partition tables (as expected with 3 TiB) which usually span (~16 KiB) beyond the beginning of the 1.2 RAID superblock (4 KiB) so I suspect that the RAID superblock was overwritten. A tiny hope is that the RAID member was actually in a partition but the geometry in the partition table is wrong or the kernel does not read it properly (I have seen this once). You can check the partition table and how the kernel sees the partition with fdisk -l /dev/sdb cat /sys/block/sdb/sdb1/start cat /sys/block/sdb/sdb1/size > On Wed, Jan 24, 2024 at 7:13 PM RJ Marquette <rjm1@xxxxxxxxx> wrote: >> >> It looks like this is what happened after all. I searched for "MBR Magic aa55" and found someone else with the same issue long ago: https://serverfault.com/questions/580761/is-mdadm-raid-toast ; Looks like his was caused by a RAID configuration option in BIOS. I recall seeing that on mine; I must have activated it by accident when setting the boot drive or something. >> >> I swapped the old motherboard back in, no improvement, so I'm back to the new one. I'm now running testdisk to see if I can repair the partition table.
