On Wednesday June 29, mlaks@xxxxxxxxxxx wrote: > Hi, > I described on this list (a few days ago) how I physically removed one of 2 > drives from a raid 1 array. I then took it to another computer to use it as a > second copy of the data. > > > > That worked fine, although I described at that time that my linux box would > not boot normally until I ran mdadm -A --run /dev/md0 /dev/hdb1 > with the --run option > as the raid 1 would not start in the degraded state otherwise. This is a safety feature of mdadm. It makes it harder to accidentally started an array without all devices being present. mdadm will only start a degraded array if "--run" is explicitly given, or if it is starting it under "--assemble --scan", and it has searched for drives itself and not found them all. > > I was wondering. > > imagine I have /dev/md0 composed of /dev/hdb1 and /dev/hdg1 > > What is the effect of the command > > > mdadm --manage /dev/md0 -f /dev/hdg1 > > Ie: If I "fail" the drive in this way: > 1) will the remainder of the array (ie /dev/md0 composed of /dev/hdb1) now > boot without the --run being added in? See above. If you are using mdadm.conf and "mdadm -As" to start the arrays, the fact that one is missing isn't a problem. > 2) Will I still be able to take the drive /dev/hdg1 and use it on another > machine as a copy of the data from the array? Yes, this should work. > 3) If the answer to 2 is no, should I do > a) remove drive /dev/hdg1 physically (machine off) > b) then after booting without /dev/hdg1 via the --run > run the command > mdadm --manage /dev/md0 -f /dev/hdg1 (even though it is not on the > machine... This is meaningless in the context. You cannot fail a drive that isn't present. > then will it boot without the --run added in. See above for when --run is needed. > > thanks, > > I am simply not sure of what -f does... It simulates an error on that drive and causes it to be excluded from the array. No further IO is performed to the drive by md. NeilBrown - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
