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Links for 2013-11-15

  • RocksDB

    ‘ A persistent key-value store for fast storage environments’, ie. BerkeleyDB/LevelDB competitor, from Facebook.

    RocksDB builds on LevelDB to be scalable to run on servers with many CPU cores, to efficiently use fast storage, to support IO-bound, in-memory and write-once workloads, and to be flexible to allow for innovation. We benchmarked LevelDB and found that it was unsuitable for our server workloads. Thebenchmark results look awesome at first sight, but we quickly realized that those results were for a database whose size was smaller than the size of RAM on the test machine – where the entire database could fit in the OS page cache. When we performed the same benchmarks on a database that was at least 5 times larger than main memory, the performance results were dismal. By contrast, we’ve published the RocksDB benchmark results for server side workloads on Flash. We also measured the performance of LevelDB on these server-workload benchmarks and found that RocksDB solidly outperforms LevelDB for these IO bound workloads. We found that LevelDB’s single-threaded compaction process was insufficient to drive server workloads. We saw frequent write-stalls with LevelDB that caused 99-percentile latency to be tremendously large. We found that mmap-ing a file into the OS cache introduced performance bottlenecks for reads. We could not make LevelDB consume all the IOs offered by the underlying Flash storage.
    Lots of good discussion at too.

    (tags: flash ssd rocksdb databases storage nosql facebook bdb disk key-value-stores lsm leveldb)

  • Amazon Route 53 Infima

    Colm McCarthaigh has open sourced Infima, ‘a library for managing service-level fault isolation using Amazon Route 53’.

    Infima provides a Lattice container framework that allows you to categorize each endpoint along one or more fault-isolation dimensions such as availability-zone, software implementation, underlying datastore or any other common point of dependency endpoints may share. Infima also introduces a new ShuffleShard sharding type that can exponentially increase the endpoint-level isolation between customer/object access patterns or any other identifier you choose to shard on. Both Infima Lattices and ShuffleShards can also be automatically expressed in Route 53 DNS failover configurations using AnswerSet and RubberTree.

    (tags: infima colmmacc dns route-53 fault-tolerance failover multi-az sharding service-discovery)

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