On 9 December 2017 at 06:56, Andrei Borzenkov <[email protected]> wrote: > [...] > Firmware is unaware of MD RAID and each partition is individually and > independently writable by firmware.
1. "Firmware is unaware of MD RAID". I agree. 2. "... independently writable by firmware". I don't expect firmware to _write_ to the ESP (does it?!). As long as it only reads, nothing will get out of sync. > Pretending that you can mirror them > on OS level is simply wrong. I think that statement is correct for all md raid setups _except_ read-only access to raid 1 and with metadata 0.90 or 1.0 (superblock at the end of device). Because in that case, a filesystem written on the md array aligns with the underlying block device. So when the system boots, EFI firmware can read /dev/sda1 and see the very same filesystem that the OS put on /dev/md127. Having ESP on an mdadm raid 1 array really works. (I now have a setup of this myself.) But due to $ bootctl --path=/mnt/boot install Failed to probe partition scheme "/mnt/boot": Input/output error , which my OS installer runs, it requires jumping through a few hoops to get it running. The hoops are: 1. Install OS with /dev/sda1 on /boot (no raid). 2. Setup /dev/md127 raid 1 on /dev/sdb1 with the 2nd device missing. (May have to copy filesystem uuid from /dev/sda1 to /dev/md127.) 3. rsync filesystem contents from /dev/sda1 to /dev/md127. 5. Repurpose /dev/sda1 as the missing device in the /dev/md127 array 6. Use efibootmgr to create the 2nd boot entry, for /dev/sdb1. I think these steps could be simplified/eliminated if "bootctl" learned about mdadm (level 1) arrays. Best regards, Bjørn Forsman _______________________________________________ systemd-devel mailing list [email protected] https://lists.freedesktop.org/mailman/listinfo/systemd-devel
