2022, Volume 23, Issue 11
Frontiers of Information Technology & Electronic Engineering >> 2022, Volume 23, Issue 11 doi: 10.1631/FITEE.2100566
ShortTail: taming tail latency for erasure-code-based in-memory systems
Affiliation(s): College of Computer Science and Technology, Jilin University, Changchun 130012, China; Department of Computer Science and Technology, Tsinghua University, Beijing 100084, China; Key Laboratory of Symbolic Computation and Knowledge Engineering of Ministry of Education, Jilin University, Changchun 130012, China; Beijing National Research Center for Information Science and Technology (Tsinghua University), Beijing 100084, China; less
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Abstract
s with erasure coding (EC) enabled are widely used to achieve high performance and data availability. However, as the scale of clusters grows, the server-level fail-slow problem is becoming increasingly frequent, which can create long . The influence of long is further amplified in EC-based systems due to the synchronous nature of multiple EC sub-operations. In this paper, we propose an EC-enabled in-memory storage system called ShortTail, which can achieve consistent performance and low latency for both reads and writes. First, ShortTail uses a lightweight request monitor to track the performance of each memory node and identify any fail-slow node. Second, ShortTail selectively performs degraded reads and redirected writes to avoid accessing fail-slow nodes. Finally, ShortTail posts an adaptive write strategy to reduce write amplification of s. We implement ShortTail on top of Memcached and compare it with two baseline systems. The experimental results show that ShortTail can reduce the P99 by up to 63.77%; it also brings significant improvements in the median latency and average latency.
Keywords
Erasure code ; In-memory system ; Node fail-slow ; Small write ; Tail latency
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