On Wed, 22 Feb 2017, 张柏年 wrote:
> The backing device /dev/md0 was a raid 0 array with 2 disks and 64k
> stripe size. The bcache device was created like this:
>
> sudo make-bcache -B /dev/md0
>
> I have just learned from the bcache kernel document that data-offset
> shoud be provided for data alignment, if the backing device is an array.
> Is there any way to correct this? ps: /dev/bcache0 has already been
> formated as btrfs
I think you might be stuck without a backup/format/restore. Technically,
you could do something like this but its dangerous unless you get it just
perfect:
1. shrunk btrfs to minimum size
2. Detach any writeback bcache caches
3. Use some tool (not sure what) to move each Nth block to the (N-1)th
block location aligned to the offset you want (sounds like 64k-8k or
maybe 128k-8k) starting from the *END* of the disk.
4. Re make-bcache with the right block offset using your new start of data
offset from #3.
5. Register bcache, attach any caches you want
6. Resize btrfs to use the full disk again.
Try this at your own risk, and definitely test it on another environment
first! If you are able to make this work, then please write back and let
us know what tool you used so we can have a procedure available for
others!
-Eric
--
Eric Wheeler
>
> Thanks,
> Bonian ZhangN嫥叉靣笡y???氊b瞂???千v豝???藓{.n???壏???{眒茰呰Ф洝塄}???财爖???j:+v墾???珣赙zZ+€???zf＂穐殘???啳嗃i???鄗???畐ア???櫒璀??????撷f
