Re: Replacing the caching device (SSD) of a bcache set

[Kent Overstreet <kmo-PEzghdH756F8UrSeD/g0lQ@public.gmane.org>]

On Thu, Aug 08, 2013 at 02:17:24PM +0200, Josep Lladonosa wrote:
> Hello,
> 
> I am running a root file system (/) in a bcache set (/dev/sda3 as the
> backing device and /dev/sdb -the SSD- as the caching device).
> 
> I want to replace the caching device with another hardware.
> 
> The question is, which is the best procedure to replace it? I was thinking
> about:
> 
> - turn off computer.
> - replace SSD with the new one.
> - turn on computer.
> 
> It seems to me very simple, perhaps too much. Does it need any other
> step? Reattaching?

Detach the bcache device from the cache set first - _definitely_ do that
first if you're using it in writeback mode

echo 1 > /sys/block/bcache0/bcache/detach

Unregistering the cache set detaches it from every attached device too:
echo 1 > /sys/fs/bcache/<cache set>/unregister