foodbaby + distributed-systems   9

Limplock: Understanding the Impact of Limpware on Scale-Out Cloud Systems
We highlight one often-overlooked cause of performance failure: limpware – “limping” hardware whose performance degrades significantly compared to its specification. We report anecdotes of degraded disks and network components seen in large-scale production. To measure the system-level impact of limpware, we assembled limpbench, a set of benchmarks that combine dataintensive load and limpware injections. We benchmark five cloud systems (Hadoop, HDFS, ZooKeeper, Cassandra, and HBase) and find that limpware can severely impact distributed operations, nodes, and an entire cluster. From this, we introduce the concept of limplock, a situation where a system progresses slowly due to the presence of limpware and is not capable of failing over to healthy components. We show how each cloud system that we analyze can exhibit operation, node, and cluster limplock. We conclude that many cloud systems are not limpware tolerant.
distributed-systems  papers 
16 days ago by foodbaby
DBMS Musings: NewSQL database systems are failing to guarantee consistency, and I blame Spanner
This fact has significant ramifications when considering the availability vs. consistency tradeoff that was purported by the CAP theorem. It is not the case that if we guarantee consistency, we have to give up the guarantee of availability. We never had a guarantee of availability in the first place! Rather, guaranteeing consistency causes a reduction to our already imperfect availability.
CAP  distributed-systems 
8 weeks ago by foodbaby

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