OpsCenter 5.0 User Guide

Advanced system alert metrics

As with any database system, Cassandra performance greatly depends on underlying systems on which it is running. To configure 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.

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 CPUs.
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.

Windows memory metrics

Metric Definition
Available memory Physical memory that is not being used.
Pool nonpaged Physical memory that stores the kernel and other system data structures.
Pool paged resident Physical memory allocated to unused objects that can be written to disk to free memory for reuse.
System cache resident Physical pages of operating system code in the file system cache.

Windows CPU metrics

Metric Definition
Idle Percentage of time the CPU is idle.
Privileged Percentage of time the CPU spends executing kernel commands.
User Percentage of time allocated to user processes.

Windows 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.
Show/hide