Am 05.05.20 um 10:11 schrieb Stefanie Leisestreichler: > I want to test if grub is installed on both of the HDs which are part of > my raid1 array. I wonder which would be the best solution to do so. > > I think I will archive that when I shutdown the computer, make /dev/sda > powerless and see if it is able to boot from /dev/sdb. > > If it is not booting /dev/sdb will have no changes, I would shutdown, > connect /dev/sda with power again, turn it on and do a "grub-install > /dev/sdb". Depending on the state of the array (I guess it will need > recovery) I would do a "mdadm /dev/md0 --add /dev/sdb1". After recovery > I would try it again. grub is *before* the RAID partitions and you need to run "grub2-install /dev/sda" as well as "grub2-install /dev/sdb" and you have to repeat that every time a disk fails and is replaced the boot loader is in front of the first partition and that was the reason a few years ago that you had to make sure there are 2 MB instead of the old 512 KB by switch to grub2 on machines dating back to 2008 or so where the default was smaller > If it is booting from /dev/sdb this HD will have "more" data because of > the one boot process than /dev/sda. I am not sure if it is a good idea > to shutdown and just connect /dev/sda with power again, boot (assuming > /dev/sda is the standard boot medium) because I do not know in which > state the array will be. What to do in case I do not want to loose data > from the last boot process with /dev/sdb? Change boot medium to /dev/sdb > and do a "mdadm /dev/md0 --add /dev/sda1" to get it recovered again > without loosing the "added" data (i.e. in /var/log) from booting? Also > device identifiers could change I guess. Even if I am fine with loosing > the "added" data from booting with /dev/sdb, will - when booting again > from /dev/sda - /dev/sda be the master in the array again? > > It is not clear to me if I understood correctly in which case which > array member will be the master which will be the base for recovery. Is > it always the HD one booted from? > > Could you please help me with that? you shouldn't remove disks and put them back without a good reason and verify booting is not a good one just change the boot order, switch the cables or explicit select both disks in BIOS
