I have a Linux server system installed on a SSD and a HDD for user data. As there is space left on the SSD, I want to use it as a read cache for the HDD.
Looking at the possibilities, I found:
dm-cache: Needs a lot of reads before caching shows performance improvements according to https://www.redhat.com/en/blog/improving-read-performance-dm-cache. I think in my use case this is not a good strategy.
lvmcache: Builds on dm-cache and I'd need to put SSD and HDD into one LV. I'd like to keep the cache transparent, so I can easily but the HDD into another system without having to do LVM magic first.
Bcache: I'd need to format the HDD for Bcache. Not what I want.
Flashcache: Sounds like what I want (just switch it on), but not actively maintained anymore according to https://github.com/facebookarchive/flashcache.
EnhanceIO: Builds on Flashcache, but dead since 2015.
Is there anything similar to Flashcache or EnhanceIO, but still actively maintained?