Title
Managing Response Time Tails by Sharding.
Abstract
Matrix analytic methods are developed to compute the probability distribution of response times (i.e., data access times) in distributed storage systems protected by erasure coding, which is implemented by sharding a data object into N fragments, only K<; N of which are required to reconstruct the object. This leads to a partial-fork-join model with a choice of canceling policies for the redundant N−K tasks. The accuracy of the analytical model is supported by tests against simulation in a broad range of setups. At increasing workload intensities, numerical results show the extent to which increasing the redundancy level reduces the mean response time of storage reads and significantly flattens the tail of their distribution; this is demonstrated at medium-high quantiles, up to the 99th. The quantitative reduction in response time achieved by two policies for canceling redundant tasks is also shown: for cancel-at-finish and cancel-at-start, which limits the additional load introduced whilst losing the benefit of selectivity amongst fragment service times.
Year
DOI
Venue
2019
10.1145/3300143
TOMPECS
Keywords
Field
DocType
Sharding, parallel task processing, performance, quality of service, response time
Mean and predicted response,Computer science,Distributed data store,Response time,Algorithm,Quantile,Probability distribution,Redundancy (engineering),Data access,Erasure code,Distributed computing
Journal
Volume
Issue
ISSN
4
1
2376-3639
Citations 
PageRank 
References 
0
0.34
0
Authors
4
Name
Order
Citations
PageRank
Peter G. Harrison187098.29
Naresh M. Patel2243.72
Juan F. Pérez300.34
Zhan Qiu4394.51