format- new cache device with make-bcache -C /dev/sdf1 and take a note of the setUUID of that device.If you want to repartition the caching device, you need to reboot, because bcache still locks the partitions unless you unregister it.

Remove the cache device just as Martin von Wittich wrote, by echoing setUUID into /sys/block/bcache0/bcache/detach.Make sure that nothing is using that bcache0 device.Lets say we are talking about the device /dev/bcache0, the new cache device is /dev/sdf1 and the backing device is /dev/md1. Suppose you've set up successfully a bcache, you are already working on it, put there a lot of important data too big to simply backup and start over, when you realized, that you'd better replace the caching device. The state file should say no cache after that: host ~ # cat /sys/block/bcache0/bcache/state So for example in this case, run: echo eb99feda-fac7-43dc-b89d-18765e9febb6 > /sys/block/bcache0/bcache/detach w- 1 root root 4096 Feb 7 07:17 register_quiet To determine the necessary cache set UUID, look in /sys/fs/bcache/: host ~ # ll /sys/fs/bcache/ĭrwxr-xr-x 7 root root 0 Feb 19 00:11 eb99feda-fac7-43dc-b89d-18765e9febb6 To safely remove the cache device, you can detach the cache set from the bcache device: echo > /sys/block/bcache0/bcache/detach

I do think though that bcache is still pretty touchy, so I'd recommend that you try that with a VM or a physical test machine first. I haven't tried to remove the cache device while the machine is powered down, so I can't say anything about that. Expect the bcache device to stall completely if that happens. Only one cache device can be added to a group of backing devices. The cache device can be a whole device, a partition or any other standard block device. I used bcache only in a writethrough configuration, and IIRC even then bcache doesn't like at all if the cache device vanishes while the machine is running. Format the cache device (This will typically be your SSD).

About cache device disk