When I try to register my bcache backing device:

echo $backing | sudo tee /sys/fs/bcache/register

I get Invalid argument

The cache device is already registered.

1 Answer 1


First, try some clean-up:

echo $cset_uuid | sudo tee /sys/fs/bcache/pendings_cleanup
echo $backing_uuid | sudo tee /sys/fs/bcache/pendings_cleanup

Use bcache-super-show to get the uuids.

Then try again to register:

echo $cset_uuid | sudo tee /sys/fs/bcache/register
echo $backing_uuid | sudo tee /sys/fs/bcache/register

The cache uuid should exist in /dev/fs/bcache if the cache device is successfully registered.

If bcache-super-show says that that the backing dev.data.cache_state state is clean and the cset.uuid consists only of zeros, the bcache device is in the invalid state and must be recreated. [source]

However, if clean, you could try force-starting the backing device without cache device:

echo 1 | sudo tee /sys/class/block/$dev/bcache/running

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