Scylla Operations Course [Part 1]

Nodetool and Logs

• Nodetool is a command-line interface that enables managing and collecting information on Scylla clusters.

• It has two types of commands: informative commands and management commands. - - On systems with systemd, Scylla logs can be retrieved with the journalctl command.

  Journalctl commands

• on distribution with systemd, scylla logs are written to systemd journal.

• you can retrieve logs using journalctl commands
• more info here, freedesktop.org/software/systemd/man/journa..

Cassandra Query Language (CQL)

• query language for scylla db
• primary and basic way to interact with scylla db
• Connecting to cql shell > cqlsh [$NodeName]

Cassandra stress tool

• this can help with data modeling, size estimation, SLA estimates, etc.
• user defined mode is good for simulating real workloads.

Tracing

• Useful for observing behaviour of different queries
• Useful for Network Issues, replication factor, and Data transfers
• Trace cqlsh session with TRACING ON | OFF commands Types of Tracing
• Probabilistic tracing, picks up random queries with some defined probability
• Slow query, Records queries with handeling time more than specified -Tracing is costly affair don't enable it by default and only use for small period of times

Bootstrap a new node into cluster

Edit scylla.yaml file and alter following parameters

• cluster name
• listen address
• seeds -rpc address
• auto bootstrap
• start scylla server on new node
• verify if the new node joined the circle.

Reference - university.scylladb.com/courses/scylla-oper..