On 27/08/2012 20:17, Kent Overstreet wrote:

On Mon, Aug 27, 2012 at 12:14 PM, Jonathan Tripathy [off-list ref] wrote:

quoted

Hi Everyone,

I'm running bcache on my md raid device for use with my xen machine (via
LVM). It works very well for Linux DomUs. However, I'm having some trouble
installing Windows. When I enter the WIndows 2008 setup, it refuses to
install to the LV volume. Reading the mailing lists, I feel this may have
something to do with the block size that bcache is using.

Assuming that my cache is md0, and my spindles are md1, it is my
understanding that to change the block size I would have to do:

make-bcache --block 512 --cache /dev/md0
and
make-bcache --block 512 --bdev /dev/md1

However, this doesn't appear to work is both of the above devices are
already set for bcache (The block size seems to still be '1' according to
the output that make-bcache gives).

That's the output you want - it's displaying in units of 512 byte sectors

Hi Kent,

Thanks for the reply. However, my device appears to still have a block 
size of 4.0k:

# cat /sys/fs/bcache/c215aa0a-c722-48e4-afcb-0ab8946d303c/block_size
4.0k

Maybe I have to deregister the devices first?

Thanks