I've been considering using bcache on one of my systems, last time I checked it seemed a bit unready in terms of all the steps needed to set it up and keep it working. What has your experience been?
We spent a lot of time prototyping basically every SSD caching tech that existed at the time and bcache was the clear winner (note that dm-cache, the tech underpinning lvm-cache was pretty immature at the time).
You do need a workload with a fairly reasonable cache hitrate to get the best out of it, but that's obviously true of all such technologies.
For bugs look at: https://github.com/koverstreet/linux-bcache/issues http://dir.gmane.org/gmane.linux.kernel.bcache.devel
https://www.redhat.com/archives/dm-devel/2013-June/msg00026....
https://www.varnish-software.com/blog/accelerating-your-hdd-...