On Thu, Jul 16, 2009 at 8:59 PM, NeilBrown<neilb@xxxxxxx> wrote: > I'm not 100% sure, but a quick look at the code suggests that > 16TB is the upper limit for normal read/write operations on > a block device like /dev/md0 on a 32bit host. This is because it uses > the page cache, and that uses 4K pages with a 32bit index, hence > 16TB. Yep, you're right. Sorry, I should have looked more into that first. I was assuming LBD took care of that somehow, because the kernel docs just say that LBD allows it to go over 2TB, and doesn't mention the new 16TB upper limit. > However this doesn't explain why it seems to work for RAID5. If I > am right, RAID5 should fail in the same way as RAID0. > But I would certainly expect RAID0 to work if anything does. > And again you're correct. It eventually failed the comparison on RAID5. But it failed in a much different way on RAID5 than RAID0 for some reason. The same disk set on an x86_64 machine appears to be working fine. Sorry for the false alarm. So I guess now my question is, should the kernel and/or mdadm refuse to create or run a >16TB array on a 32-bit kernel? :) Thanks much for your help! -Justin -- 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
