Question: How do you combine memcached, an ultra-high-performance cache system that depends on running entirely in RAM, with a dataset that is just too large for expensive (and getting even more so) RAM?
Answer: Use memcached’s external storage system, extstore, to offload some of its data to fast disk. The good thing about SSD is that it is fast and cheap, at least compared to RAM; the downside is that it is much slower than RAM… slow enough that it might just impact performance.
How much will it impact? And what happens if you use really fast SSD, like Optane?
We are fortunate to have had Dormando of memcached perform an analysis and write it up on the official memcached blog.
Head on over for a great in-depth write-up.