Managing the Transaction Log
Each database in SQL Server has at least one transaction log file. The transaction log file contains the transaction log records for all changes made in that database. By default, transaction log files have the file extension
A database can have several log files, and each log file can have a maximum size of 32TB. A log file cannot be part of a filegroup. No information other than transaction log records can be written to a log file.
Regardless of how many physical files have been defined for the transaction log, SQL Server treats it as one contiguous file. The transaction log for a database is actually managed as a set of virtual log files (VLFs). VLFs have no fixed size, and there is no fixed number of VLFs ...