# FaRM

[Article](http://nil.csail.mit.edu/6.824/2020/papers/farm-2015.pdf).

* Super fast with DRAM.
* All within one data center. Doesn't solve geo replication anyhow.
* Bottleneck - CPU.
* Sharded by key between primary/backup pairs.
* All replicas are updated if there's change. You always read from primary. If one replica is available you are good.
* All must fit in the (combined) RAM.
* Tolerate power failures - non-volatile RAM scheme (NVRAM).
* RDMA - network interface cards that can read/write memory directly.
* Kernel Bypass - app code can access network cards directly, without kernel help.
* When the battery system detects main power failure - stop all processes, write all RAM to SSD. Then die.
* RDMA - remote direct memory access. Access memory remotely without involving destination CPU at all. Append messages to a queue.
* API:
  * txCreate()
  * o = txRead(oid)
  * o.f += 1
  * txWrite(oid, o)
  * ok = txCommit()