Addition of systemd boot instructions
I just edited the main article to include the systemd boot methods that I used to get flashcache to work for me. For some reason I could not get the ramdisk instructions to work for me. However, I am assuming that is a failure on my part, rather than a failure of the instructions, and so I have decided not to edit the original instructions, but simply to augment them
Writeback and writearound
On first glance it can seem that flashcache does not allow writeback and writearound modes. In the past, some users have written that flashcache does not support writeback and writearound. On the contrary, the flashcache documentation here:  explicitly states that writeback and writearound are supported:
Flashcache is a block cache for Linux, built as a kernel module, using the Device Mapper. Flashcache supports writeback, writethrough and writearound caching modes. This document is a quick admministration guide to flashcache.