On Sun, Apr 19, 2009 at 11:04:07PM +0200, Piergiorgio Sartor (piergiorgio.sartor@xxxxxxxx) wrote: > > Why would you want a RAID-1 without superblock. > Ah! I was thinking about it as a method to > build a RAID with an already existing disk > or partition, which cannot be modified. Well, that it isn't. Although of course if you have multiple partitions on the disk, you can build RAID on them separately, possibly leaving some out and it might be useful in some situaitions, but that's apparently not what you had in mind. > So, let's say I've already a disk with some > data and I want/need to protect it with a > RAID configuration, but I cannot re-create > the RAID from scratch, because this will > damage the content of the disk. Well, you could create the RAID as degenerate on the new disk(s) only, copy the data over and then add the old disk to complete array. > For example, I found consistent to create the > array with the correct disk and "missing", > then add the mirror. I'm not sure what you mean, unless it's just what I suggested above. > Of course, if there is a known order for the > resync, then it would be enough to build > the array with this in mind. > The issue could also be that the "primary" > disk could be updated alone, sometimes. What would "updating" the disk mean here? If you want to have two disks of different sizes so that the "extra" space in the bigger one is usable, just not RAIDed, it's easy: just build the RAID out of the entire smaller disk and a similarly-sized partition in the bigger one, and use the remainder of the latter as a regular partition. And upgrading the disks one at a time in such a setup is perfectly possible, without any backup/restore cycles, too. (Although backups are still recommended, of course.) -- Tapani Tarvainen -- 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
