On 05/05/20 09:11, Stefanie Leisestreichler wrote: > Hi. > 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. > > If it is booting from /dev/sdb this HD will have "more" data because of > the one boot process than /dev/sda. Why? If it boots to the grub menu, just hit an arrow key to stop the timeout, and then hold the power button for 5 secs to shut it down again. > 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? Which would matter why? If you're worried about downloading mail etc, just kill the network temporarily. > 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? > The "master" if recovery is required will be the "older" one - in this case sda because it was disconnected. HOWEVER. Just check whether you have a bitmap or journal enabled. You can't have both at once, but the result should be that sda rejoins the array cleanly, raid has a record of which writes occurred while it was offline, and it will be updated. > Could you please help me with that? > > Thanks, > Steffi Cheers, Wol
