For those thinking about potentially running a Linux system with a combination of SSD and HDD so that the solid-state drive would be able to act as a performance cache for commonly used data, BCache and LVM-cache/dmcache are two of the commonly used solutions.
For those interested in LVM Cache or BCache, Fedora developer Vratislav Podzimek has written a lengthy blog post comparing these two hybrid caching solutions for Linux -- including setup procedures and steps for Fedora users.
At the end of the post, Vratislav Podzimek concluded that one of these caching solutions isn't definitely better than the other. If you're looking for an easy setup procedure though, the win would likely be handed to BCache. He concluded, "if somebody just wants to make use of their SSD by setting up SW cache on a fresh pair of SSD and HDD and they don’t want to bother with all the LVM stuff and commands, the bcache is probably the better choice. And as usual, having to independent and separate solutions for a single problem leads into many new and great ideas that are in the end shared because what gets implemented in one of them usually sooner or later makes it to the other too, typically even improved somehow. Let’s just hope that this will also apply to bcache and LVM cache and that both technologies are deployed widely enough to be massively supported, maintained and further developed."
You can read the lengthy post in full via
Podzimek's personal blog. Performance benchmarks of these Linux hybrid caching solutions weren't shared in that blog post, but on my (albeit very lengthy) TODO list has been plans to do some various SSD+HDD Linux caching benchmarks. Express interest via the forums,
on Twitter, or
with tips if you'd be interested in such tests.