UNIX and Linux iostat logs: Reduce log size and convert to TSV format¶

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Use case¶

Reduce the size of Unix and Linux iostat logs by removing unnecessary fields, replacing invalid values, and optimizing log storage. Extract essential fields while maintaining compatibility with the Splunk Common Information Model (CIM).

Version 0.4.1¶

Version 0.4.1 of the `UNIX and Linux iostat logs: Reduce log size and convert to TSV format` template was released on March 19, 2025.¶

Template details¶

Compatibility¶

This template is compatible with Splunk Add-on for Unix and Linux v9.2.0 and v10.0.0.

Template description¶

This is a sample pipeline that reduces the size of iostat logs coming from the Splunk Add-on for Unix and Linux while preserving compatibility with the Splunk Common Information Model (CIM). This pipeline processes data with the iostat source type and performs the following:

Replaces repeated space characters used as delimiters in the logs with a single tab character (\t) or a custom delimiter.
Removes unnecessary data from the logs.
Converts the logs into tab-separated key-value pair format.
Optionally updates the values of the source and sourcetype event fields.

Supported sourcetype¶

This pipeline only works on complete iostat events that include the header row and all subsequent rows.

Template outline¶

The template consists of several custom functions followed by a pipeline that uses these functions.

Functions¶

The following table shows all functions, including possible configuration options.

Function name	Description	Configuration options
`replace_multiple_whitespaces`	Replaces repeated space characters in the logs with a single tab character (`\t`) or a custom delimiter.	`$delimiter`: The replacement delimiter to use instead of repeated space characters (default: `\t`).
`remove_trailing_zeros`	Removes trailing zeros from decimal values in the logs. For example, `10.00` is transformed into `10`.	No configuration options.
`extract_split_rows`	Splits the logs into rows using the newline character (`\n`) as the delimiter and further splits the rows into columns using the tab character (`\t`) or a custom delimiter.	`$row_split_separator`: The delimiter for splitting rows into columns (default: `\t`).
`find_header_indexes`	Assigns a number to each log field. Other functions in this pipeline use these numbers as indexes for accessing the log contents.	No configuration options.
`drop_empty_records`	Removes rows where the value of all of these fields is `0.00`: `rkB/s`, `wkB/s`, `w/s`, and `%util`.	No configuration options.
`replace_await`	Replaces any `?` values in the `await` field with an empty value.	No configuration options.
`rows_to_delimiter_separated`	Transforms the logs from JSON array format to tab-separated key-value pair format.	`$delimiter`: The delimiter to use between columns (default: `\t`).
`apply_transformations`	Groups the previously defined custom functions together to apply transformations to the logs.	No configuration options.
`update_source_and_source_type`	Appends a suffix to the values in the `source` and `sourcetype` fields, if those fields exist in the event.	`$suffix`: The suffix to append to the `source` and `sourcetype` values.

Pipeline¶

This pipeline has the following outline:

Replaces repeated space characters with tabs using the replace_multiple_whitespaces function.
Splits the logs into rows and columns using the extract_split_rows function.
Assigns indexes to the log fields using the find_header_indexes function.
Removes unnecessary rows using the drop_empty_records function.
Replaces invalid values in the await field using the replace_await function.
Transforms the logs into tab-separated key-value pair format using the rows_to_delimiter_separated function.
Optionally updates the source and sourcetype fields using the update_source_and_source_type function.
Sends the transformed logs to the destination.

Configuration instructions¶

For significant license savings, use the drop_empty_records and replace_await functions to remove unnecessary rows and replace unnecessary values in specific fields. You can comment out any of these functions you do not want to apply by prefixing it with //, allowing you to retain specific data that might otherwise be removed or modified.

Optionally, use the update_source_and_source_type function to append a suffix to the source and sourcetype fields, helping to distinguish modified logs from unmodified ones.

Notes¶

Ensure that the iostat source type is properly configured in your Splunk deployment.
Customize the pipeline as needed to meet your specific requirements.
If using the update_source_and_source_type function, ensure that the suffixed source type is configured in your Splunk platform deployment with appropriate time extraction and line-breaking settings.