jm + scylladb   2

Taming the Beast: How Scylla Leverages Control Theory to Keep Compactions Under Control - ScyllaDB
This is a really nice illustration of the use of control theory to set tunable thresholds automatically in a complex storage system. Nice work Scylla:

At any given moment, a database like ScyllaDB has to juggle the admission of foreground requests with background processes like compactions, making sure that the incoming workload is not severely disrupted by compactions, nor that the compaction backlog is so big that reads are later penalized.

In this article, we showed that isolation among incoming writes and compactions can be achieved by the Schedulers, yet the database is still left with the task of determining the amount of shares of the resources incoming writes and compactions will use.

Scylla steers away from user-defined tunables in this task, as they shift the burden of operation to the user, complicating operations and being fragile against changing workloads. By borrowing from the strong theoretical background of industrial controllers, we can provide an Autonomous Database that adapts to changing workloads without operator intervention.
scylladb  storage  settings  compaction  automation  thresholds  control-theory  ops  cassandra  feedback 
june 2018 by jm
CharybdeFS: a new fault-injecting filesystem for software testing
a FUSE-based filesystem from ScyllaDB to test filesystem-related failure scenarios. great idea
fuse  software  testing  scylladb  filesystems  disk  charybdefs  fault-injection  tests 
february 2016 by jm

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