
Evolution of Application Data Caching: From RAM to SSD - ceohockey60
https://medium.com/netflix-techblog/evolution-of-application-data-caching-from-ram-to-ssd-a33d6fa7a690
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hbrundage
Does extstore also use the same slab allocator that memcached does in memory?
Cause if so I feel that disk usage might actually be worse than imagined due
to the slab packing problems. I think the design decision to keep everything
in memcached makes a lot of sense, but RocksDB seems like an odd choice for
the first iteration. It’s big claim to fame is durability while achieving high
performance, and it shines in situations like MyRocks, but for caching,
especially where replication is handled on top of the things writing to disk,
that doesn’t seem as important. I think extstore also does compaction but on a
64M page by page basis instead of using one big log.

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ksec
>EVCache has become a fundamental tier-0 service storing petabytes of data and
hundred of billions of items,

So newest Memcache with extstore allows them instead of PB of RAM to PB of
SSD. I look at the pricing of EC2 instances, turns out it is may be a $3/hr
saving between Memory Optimised and Storage I/O optimised. On a petabytes
scale at 500GB / node that translate to roughly $4.3 million saving per month
from on demand pricing. Likely much lower from Netflix discount but still
quite a bit of money.

