On 11/21/2016 03:22 PM, Anthony Youngman wrote: > Having looked at the man page, this now seems obvious - the superblock > is at the end, so the data offset is 0. But for a 1.0 array, could we > create a data offset? > > (So, if we created a data offset, we could then move the superblock and > convert a 1.0 to 1.1 or 1.2? Okay, it can't do it now, but it looks to > me like it shouldn't be that hard ... ?) I suppose it would be possible, but defeats the purpose of having data offset == 0: making non-parity array contents directly readable outside the array. Commonly used to raid boot partitions but still have grub able to read them directly. Less of an issue today with grub2, I suppose (but I don't use bootloaders anymore, so I'm not a good resource for that). >>> But if we have a data offset with v1.2, a reshape will use that space if >>> it can rather than needing a backup file? >> > I'm guessing that 1.0 and 1.1 defaulted to no data offset to speak of? > And if we (can) create a decent data offset, we can then use that in > exactly the same way as with v1.2? V1.1 and v1.2 are identical except for the superblock offset (one 4k block difference). v1.1 reshapes just like v1.2. Phil -- 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
