On Wednesday December 1, Fabrice.Lorrain@xxxxxxxxxxx wrote: > Fabrice LORRAIN wrote: > > Hi all, > > > ... > > $ sudo mdadm --create /dev/md0 --level=5 --raid-devices=6 /dev/loop[0-5] > > > $ sudo mdadm --create /dev/md0 --force --level=5 --raid-devices=6 > /dev/loop[0-5] > > Seems to give what I expected (a raid5 pool with 6 devices, no spare). > > From mdadm man page : > "...When creating a RAID5 array, mdadm will automatically create a > degraded array with an extra spare drive. This is because building the > spare into a degraded array is in general faster than resyncing the > parity on a non-degraded, but not clean, array. This feature can be > over-ridden with the -I --force option." > > "-I" doesn't seems to be understood by mdadm. Leftover ? The "-I" is a typo in the man page. It should be ".I", which would set the "--force" in italics. > > I don't understand what the previous extract from the man page means. My > understanding is that the default behaviour of mdadm is to create a > raid5 pool in degraded mode aka with a missing drive ? Is this > correct ? Yes. That is correct. It does this because (as the man page says) you get a fully in-sync raid5 array - with all parity blocks correct - sooner. > > after > $ sudo mdadm --create /dev/md0 --force --level=5 --raid-devices=6 > /dev/loop[0-5] > > the state of the array is dirty. Why ? > > $ sudo mdadm --stop /dev/md0 followed by > $ sudo mdadm --examine /dev/loop[0-5] > > gives a clean state for each device but > > $ sudo mdadm --assemble /dev/md0 /dev/loop[0-5] keeps the dirty state of > the array. "dirty" should be changed to say "active", and probably will be in the next release of mdadm. 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
