Advanced system alert metrics

Configure advanced system metrics for memory, CPU, and disk metrics on Linux or Mac OS X. As with any database system, Cassandra performance greatly depends on underlying systems on which it is running. Before configuring advanced system metric alerts, you should first have an understanding of the baseline performance of your hardware and the averages of these system metrics when the system is handling a typical workload.

To access Advanced System metrics, choose Advanced > System in the Add Alert dialog.

Advanced Alerts submenu

Linux memory metrics

Metric Definition

Memory free

System memory that is not being used.

Memory used

System memory used by application processes.

Memory buffered

System memory used for caching file system metadata and tracking in-flight pages.

Memory shared

System memory that is accessible to `CPU`s.

Memory cached

System memory used by the OS disk cache.

Linux CPU metrics

Metric Definition

Idle

Percentage of time the CPU is idle.

Iowait

Percentage of time the CPU is idle and there is a pending disk I/O request.

Nice

Percentage of time spent processing prioritized tasks. Niced tasks are also counted in system and user time.

Steal

Percentage of time a virtual CPU waits for a real CPU while the hypervisor services another virtual processor.

System

Percentage of time allocated to system processes.

User

Percentage of time allocated to user processes.

Linux Disk metrics

Metric Definition

Disk usage

Percentage of disk space Cassandra uses at a given time.

Free disk space

Available disk space in GB.

Used disk space

Used disk space in GB.

Disk read throughput

Average disk throughput for read operations in megabytes per second. Exceptionally high disk throughput values may indicate I/O contention.

Disk write throughput

Average disk throughput for write operations in megabytes per second.

Disk read rate

Averaged disk speed for read operations.

Disk write rate

Averaged disk speed for write operations.

Disk latency

Average time consumed by disk seeks in milliseconds.

Disk request size

Average size in sectors of requests issued to the disk.

Disk queue size

Average number of requests queued due to disk latency.

Disk utilization

Percentage of CPU time consumed by disk I/O.

Mac OS X memory metrics

Metric Definition

Free memory

System memory that is not being used.

Used memory

System memory that is being used by application processes.

Mac OS X CPU metrics

Metric Definition

Idle

Percentage of time the CPU is idle.

System

Percentage of time allocated to system processes.

User

Percentage of time allocated to user processes.

Mac OS X disk metrics

Metric Definition

Disk usage

Percentage of disk space Cassandra uses at a given time.

Free space

Available disk space in GB.

Used disk space

Used disk space in GB.

Disk throughput

Average disk throughput for read/write operations in megabytes per second. Exceptionally high disk throughput values may indicate I/O contention.