cassandra disks cache on SSD

[vincent gromakowski]

I am looking for way to optimize large reads.
I have seen using SSD is a good option but out of budget, so I am looking
for a way to use some kind of tiering with few SSD caching hot data from
HDD.
I have identified two solutions and would like to get opinions from you and
if you have any experience using them:
- use ZFS with L2ARC functionality
- use Rapiddisk/Rapidcache Linux kernel module
Any opinion ? Constraints ? REX ?
Thanks