LVMcache hybrid drive setup on Debian Linux

Setup a hybrid drive using a RAID array of SSD's and another array of conventional drives to get Large, Fast, and Cheap storage. UPDATE: Since recording this video, I have learned that there are some serious drawbacks to this setup. I don't recommend that you follow this tutorial unless you are prepared to monitor for these issues.
Caveats:
1) The hidden lv's for metadata can fill up unexpectedly, leading to strange behavior. You can see how full these are in the output of "lvs -a". However, if you aren't monitoring for this, you could end up with unexpected behavior.
2) It seems that the algorithm to flush blocks from the dirty cash into the slow disks isn't very efficient. At least, it isn't very "aware" of how to efficiently write data to slow spindle drives. When a large amount of data is written to the cached device, once the dirty cache reaches a certain level, writes will block while the system "flushes" blocks from the dirty cache onto the slow disks. This tends to "thrash" the disks with a lot of random writes, and block I/O at a high level long enough to generate timeouts. So I've had several scenarios with this setup where the cache actually slowed down the entire system, rather than speeding it up. In this case, I just detached the cache device and it improved the performance.
At some point, I hope to test various configurations with ZFS and SSD's and compare performance.

Видео LVMcache hybrid drive setup on Debian Linux канала Daniel McFeeters