Log File Formats

Performance data can be stored in four formats: comma-separated-value (CSV), tab-separated-value (TSV), binary, and Perfmon format.

The fields of a record within a CSV log file are delimited by double-quotes and commas. The fields of a record within a TSV log file are delimited by double-quotes and tab characters.

The first line of CSV-format and TSV-format log files serves as the header, providing information about the format of the file, the version of the PDH interface used to create the log file, and the names and paths of each of the counters to the PDH.

Both the Perfmon and binary log file formats are proprietary formats developed at Microsoft. The Perfmon format is the format the Performance Monitor uses when it writes counter data to a log file. The binary format provides all of the information contained in the Perfmon format, but in a more space-efficient manner. The Windows 2000 Performance Monitor uses the binary format by default.

Be aware that the PDH library can open a log file in the Perfmon format only for reading.