On Thu, Sep 29, 2011 at 08:26:11PM +0100, Robin Hill wrote: > On Thu Sep 29, 2011 at 02:34:57PM -0400, William Thompson wrote: > > > Please keep me in the CC. I am not on the list. > > > > If I have a RAID1 of 2 disks and I decide to move them to another computer > > and recreate the raid, does it really need to do the initial recovery? > > > You don't need to recreate the raid at all, just reassemble it. You may > want to update the homehost though, otherwise it will (IIRC) auto > assemble to md_126 (or so) instead of md0. The reason I asked this was because a mirrored pair that I currently have is 0.90 version and I was going to use 1.0 > > For that matter, when creating a RAID1 on 2 disks, is it really needed to do > > the initial recovery? > > > > I understand why it's needed for RAID4/5/6 though. > > > Probably not, no. Anything written would go to both mirrors, and reads > of any un-mirrored areas are indeterminate anyway. You would lose the I figured this would be the case. > ability to check the array for mismatches though, and the recovery > process would bring everything into sync whenever it's run anyway. More I've rarely done this. On large disks, this takes may hours to perform. > of a question would be why not do the initial recovery? It doesn't delay > access to the array, and at least the I/O load is happening at a > controlled point (rather than at recovery time, when you have no I guess the only reason I can come up with would be to avoid extra head seeks. Well, that and the time it takes. During the initial sync, if a write happens to an area that has been synced, does it go to all drives? What about a write to an area that as not been synced yet? > control). Anyway, if you do want to avoid the initial recovery, just use > --assume-clean. I am aware of this option. I've have been fortunate with mdadm in the many years I've used it (except 1 time). -- 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
