Hi *,

Zitat von Eric Wheeler [off-list ref]:

quoted

On Wed, 8 Feb 2017, Kai Krakow wrote:
[...]  

quoted

What I meant is "make-bcacke --block X". It defaults to X=512b. I
think you may want to force it to 4k and see if your problem
persists.  

Maybe --block 4096 should be default in make-bcache?

Kent, is there any reason this wouldn't be a good idea?  

actually, make-bcache seems not to default to 512 octets. If no  
specific block size is specified on the command line, it determines  
the maximum sector size of the devices involved:

--- cut here ---

if (!block_size) {
		for (i = 0; i < ncache_devices; i++)
			block_size = max(block_size,
					 get_blocksize(cache_devices[i]));

		for (i = 0; i < nbacking_devices; i++)
			block_size = max(block_size,
					 get_blocksize(backing_devices[i]));
}

--- cut here ---

get_blocksize() queries the logical block size as reported by the  
device ( ioctl(fd, BLKSSZGET, &logical_block_size) ).

At least that's what I see at  
https://github.com/g2p/bcache-tools/blob/master/make-bcache.c, said
to be from Apr 16, 2014. And it seems to be the reason why invoking  
"make-bcache -B ... -C ..." did create a proper setup for me, while  
separating that to "make-bcache -B ..." and "make-bcache -C ..."  
created a wrongly set up caching device for me (backing device has
4k sector size, caching device 512b).