Moved from: bobsql.com
When creating or growing the database log file (LDF) a byte pattern is stamped. The pattern establishes the proper log block layout with end of log marker(s.)
SQL Server 7.0 changed the LDF format from the original, 2K, Sybase database page design to sector aligned log blocks stamped with all zeros (0x00). Creation or expansion of the LDF file involves writing the entire series of 0x00’s to the new bytes for the log.
SQL Server 16 changes the stamp to 0xC0’s instead of 0x00s.
Note: The log file stamping pattern change has been leveraged by Window Azure SQL Database