Hi all,
I just recovered my system (supermicro server) from this and thought I would share in case it is helpful. 1. Number of disks: 4 2. Filesystem setup This is a raid1 setup with crypted lvm. Grub is installed in MBR of /dev/sda # fdisk -l Disk /dev/sda: 465.8 GiB, 500107862016 bytes, 976773168 sectors Disk model: Samsung SSD 850 Units: sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disklabel type: dos Disk identifier: 0x953049db Device Boot Start End Sectors Size Id Type /dev/sda1 * 2048 585727 583680 285M fd Linux raid autodetect /dev/sda2 585728 39647231 39061504 18.6G fd Linux raid autodetect /dev/sda3 39647232 918552575 878905344 419.1G fd Linux raid autodetect Disk /dev/sdc: 931.5 GiB, 1000204886016 bytes, 1953525168 sectors Disk model: WDC WD10JPLX-00M 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: dos Disk identifier: 0x38784402 Device Boot Start End Sectors Size Id Type /dev/sdc1 2048 1953525167 1953523120 931.5G 83 Linux Disk /dev/sdd: 931.5 GiB, 1000204886016 bytes, 1953525168 sectors Disk model: WDC WD10JPLX-00M 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: dos Disk identifier: 0xa1da09f8 Device Boot Start End Sectors Size Id Type /dev/sdd1 2048 1953525167 1953523120 931.5G 83 Linux Disk /dev/sdb: 465.8 GiB, 500107862016 bytes, 976773168 sectors Disk model: Samsung SSD 850 Units: sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disklabel type: dos Disk identifier: 0x1efcfd6f Device Boot Start End Sectors Size Id Type /dev/sdb1 * 2048 585727 583680 285M fd Linux raid autodetect /dev/sdb2 585728 39647231 39061504 18.6G fd Linux raid autodetect /dev/sdb3 39647232 918552575 878905344 419.1G fd Linux raid autodetect Disk /dev/md0: 284.7 MiB, 298516480 bytes, 583040 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 /dev/md2: 419 GiB, 449865318400 bytes, 878643200 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 /dev/md1: 18.6 GiB, 19982712832 bytes, 39028736 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 /dev/md3: 931.4 GiB, 1000069595136 bytes, 1953260928 sectors Units: sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 4096 bytes I/O size (minimum/optimal): 4096 bytes / 4096 bytes Disk /dev/mapper/md1_crypt: 18.6 GiB, 19980615680 bytes, 39024640 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 /dev/mapper/vg0-root: 9.3 GiB, 9999220736 bytes, 19529728 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 /dev/mapper/vg0-usr: 4.7 GiB, 4999610368 bytes, 9764864 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 /dev/mapper/vg0-var: 4.7 GiB, 4978638848 bytes, 9723904 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 /dev/mapper/md2_crypt: 419 GiB, 449863221248 bytes, 878639104 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 [bunch of lvms for vms] 3. History of the system I installed jessie on this server in 2015 and remotely upgraded to stretch and then to buster. # uname -a Linux XXXXX 4.19.0-10-amd64 #1 SMP Debian 4.19.132-1 (2020-07-24) x86_64 GNU/Linux As with others, I was able to boot into d-i rescue mode and reinstall grub and then it booted fine. I hope this helps. It was definitely a surprise to find the server unbootable at 1am this morning! Thanks for all the work! -Devin