Q:

Aerospike performance with flash disks

I have read, that Aerospike provides better performance than other NoSQL key-value databases because it uses flash disks. But DRAMs are faster than flash disks. Then how can it have better performance than Redis or Scalaris that use only DRAMs? Is it because of the Aerospike's own system to access flash disks directly?
Thank you for answer

A:

Aerospike allows you the flexibility to store all or part of your data (part segregated by "namespaces") in DRAM or Flash (writing in blocks on  device without using a filesystem) or both DRAM and Flash simultaneously (not the best use of your spend) or both DRAM and in files in Flash or HDD (ie using a filesystem) .. DRAM with filesystem on HDD - gives performance of DRAM with inexpensive persistence of spinning disks. Finally for single value integer or float data, there is an extremely fast performance option of storing the data in the Primary Index itself (data-in-index option).  
You can mix storage options in Aeropsike. ie store one namespace records purely in DRAM, store another namespace records purely in Flash -- on the same horizontally scalable cluster of nodes.  You can define upto 32 namespaces in Aerospike Enterprise Edition.
Flash / HDD .. etc options allow you to persist your data.
Pure DRAM storage in Aerospike will definitely give you better latency performance, relative to storing on persistent layer.
Storing on Flash in "blocks" (ie without using the filesystem) in Aerospike is the sweet spot that gives you "RAM like" performance with persistence.  Other NoSQL solutions that are pure DRAM storage don't give you persistence, or there may be others that if they give you persistence with storage in files only via the filesystem, they will quite likely give you much higher latency.

