On 8/7/07, Neil Brown <neilb@xxxxxxx> wrote: > On Tuesday August 7, saeed.bishara@xxxxxxxxx wrote: > > On 8/7/07, Neil Brown <neilb@xxxxxxx> wrote: > > > On Tuesday August 7, saeed.bishara@xxxxxxxxx wrote: > > > > how can I create raid 5 array that preserves the contents of a given > > > > disk (part of the array)? > > > > I can do that in two steps, raid 5 on two disks then reshape it to be > > > > real raid5, but is there a direct way to do it? > > > > > > What do you mean by "real raid 5". Two disks are just as much an > > > array as 10. > > I meant by real raid 5 to raid 5 over 3 drives or above. > > > What do you mean by "direct". If I understand your requirements > > in one mdadm command > > > correctly, there are two obvious steps. > > > 1/ make the data appear in a raid5 > > > 2/ change the number of devices in the raid5. > > > > > > Are two steps too many? > > in this case I two options: > > 1. keep the filesystem unmounted tell step 1 in done -> the fs will > > not be available for long time > > No, it shouldn't take a long time.... > > What exactly do you have, and what exactly do you want to achieve? > > If think you started of by saying you wanted to convert a raid1 to a > raid5. Yes, that requires the filesystem to be unmounted, but only > takes seconds to achieve: > > mdadm -S /dev/md0 > mdadm -C /dev/md0 -l5 -n2 /dev/sda1 /dev/sdb1 > mount /dev/md0 > > If you have a single-disk, you first might need to shrink the > filesystem to make sure there is 128K free at the end of the device: > > umount /filesystem > resize2fs /dev/sda1 whatever-number > mdadm -C /dev/md0 -l5 -n1 /dev/sda1 missing -n1 didn't work, but -n2 succeeded. > mount /dev/md0 /filesystem > # now add the drives and grow > mdadm /dev/md0 --add /dev/sdb1 /dev/sdc1 > # wait for recovery to finish > mdadm --grow /dev/md0 --raid-disks=3 > > something like that.. great, this actually does the migration from single drive to raid5 as I was looking for. thanks. > > 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
