Monitoring a Linux host

The CPU usage values, when combined, provide a detailed view of how the CPU resources are being utilized on a Linux host.

You can measure the used value in percentage by using the formula (total - actualFree) ÷ total. The sensor uses the actualFree value that is the real-constrained memory that includes free and cached memory, instead of free, which is a low value (used for caching or buffering).

The CPU load metric tracks the average number of processes competing for CPU resources, displayed as a time-series graph.

The CPU usage metric displays the following metrics in percentage on a graph for a selected time period for each CPU:

The following table outlines the Individual GPU usage values:

The metric is collected from nvidia-smi. The following table outlines the supported version of Nvidia graphics cards:

The following list of processes uses GPU:

The following table outlines the supported version of Nvidia graphics cards for GPU memory:

The following table outlines the unit for memory:

The values are displayed on a graph for a selected time period.

By default, paging activity metrics are not collected. You can enable the collection of paging activity metrics by setting the collectPagingActivity to true in the configuration.yaml file.

com.instana.plugin.host:
  collectPagingActivity: true # [true, false]

Open files usage when available on the operating system; current vs max. The values are displayed on a graph for a selected time period.

By default, process statistics metrics are not collected. You can enable the collection of process statistics metrics by setting the collectSystemProcess to true in the agent configuration.yaml file.

com.instana.plugin.host:
  collectSystemProcess: true # [true, false]

By default, RPC client and server activity metrics are not collected. You can enable the collection of RPC activity metrics by setting the collectRpcActivity to true in the agent configuration.yaml file.

com.instana.plugin.host:
  collectRpcActivity: true # [true, false]

These metrics provide insights into file system performance, capacity, and usage, allowing administrators to monitor and optimize their storage systems effectively.

* The total, read, and write usage datapoint metrics display the disk I/O utilization as a percentage.

* Leaked (refers to deleted files that are in use and equates to capacity - used - free. You can find these files with lsof | grep deleted).

** The Total Utilization, Read Utilization, and Write Utilization datapoints are not supported for Network File Systems (NFS).

By default, Instana only monitors local file systems. You can list the file systems that are monitored or excluded in the configuration.yaml file.

The name for the configuration setting is the device name, which you can obtain from the first column of mtab file or df command output.

You must specify temporary file systems in the following format: tmpfs:/mount/point.

The following example shows the list of file systems that are monitored:

com.instana.plugin.host:
  filesystems:
    - '/dev/sda1'
    - 'tmpfs:/sys/fs/cgroup'
    - 'server:/usr/local/pub'
 

The following example shows the file systems that are included or excluded:

com.instana.plugin.host:
  filesystems:
    include:
      - '/dev/xvdd'
      - 'tmpfs:/tmp'
      - 'server:/usr/local/pub'
    exclude:
      - '/dev/xvda2'
 

The following table covers metrics that are related to Disk

The following table outlines the network traffic and errors per an interface.

These metrics provide insights into TCP connection activity, including established connections, segment transmission rates, and error occurrences.

The top process list provides comprehensive insights into running processes, including process identifiers, names, resource consumption metrics, and ownership information. This list is updated every 30 seconds and displays only processes that meet specific resource utilization thresholds: processes consuming more than 10% CPU over the last 30 seconds or processes with memory usage (RSS) exceeding 512 MB.

To generate a unified view combining the top 10 CPU-intensive and top 10 memory-intensive processes, configure combineTopProcesses to true. This configuration includes processes in the combined list regardless of whether they meet the standard thresholds. When a process appears in both the CPU and memory top 10 lists, it is listed only once, resulting in a combined list of up to 20 unique entries.

com.instana.plugin.host:
  combineTopProcesses: true # [true, false]
 

Linux top semantics are used. 100% CPU refers to full use of a single CPU core, and you can search a history of snapshots from the previous month. The normalized CPU is calculated by dividing the CPU by the number of logical processors.