...
- How do durability and reliability tie in to the discussion?
Evaluation
- Reqs/sec/GB
- Index size/GB
Questions
- How much metadata space is needed for all tables/applications?
- Up to 2^48 objects, 128 bit (16 byte) key, size (4-8 bytes), permissions or appid if not in address (2-4 bytes)
- (2^43)*16 = 128 TB
- How does metadata replication occur and what is the frequency?
- Lazily
...
- - Capacity
- + Throughput
- + Mitgates hot spots
- If there is a hot spot, data reduction may not solve overloading problems
- If a single server can handle 1M requests/second, is there any need to replicate?
- If the load gets too high, perhaps reduce the load by reducing the amount of data stored on a server, rather than replicating the data
- + Latency
- Eliminates cross data center requests (East to West Coast datacenters)
- - Consistency
- A system without replication would be much easier to manage
Evaluation
- Reqs/sec
- MTBF if considering Reliability
Locality
Effects
- + Network traffic
- + Latency for serial requests
- + Performance isolation in multi-tenant environments
- + Economy of metadata
- For example, only access control information for data which resides on a host must be replicated to that host
- Is there any locality in interesting database applications?
- The most interesting form of locality is locality within a request: would like to satisfy each request with a single call to a single server, if possible
Evaluation
- Bytes transfered/response
- Reqs/sec
- bps leaked between users
- Metadata/GB