2.1 Log File Format

The following figure is a simplified representation of the log file. The log file header contains identification information, stores the size of the metadata field, and stores the location of the last valid metadata to indicate the end of the log.

Log file Structure

Figure 1: Log file Structure

Each metadata item consists of a metadata header and metadata entries. The first entry of the metadata header stores the previous metadata location in the log file. This is used in traversing the metadata structures from the bottom of the log.

Metadata structure

Figure 2: Metadata structure

The log file is optimized for writing sequentially. Therefore, the metadata describing each log entry is written after each set of data entries.