SQL Server Backup Failure This one has me stumped and I'm sure there is a simple explanation that I cannot fathom at present.

A few informational pieces:


vCentre Database - SIMPLE Recovery Model
SQL Server 2008 R2 Standard Edition


We have a FULL Database backup (driven by Ola's scripts) that is failing as a result of a full transaction log.   We are running the backup WITH CHECKSUM which I suspect may be the cause, but I don't entirely understand why the FULL Backup would need to perform a write operation against the database log file. 

I'm conscious that the FULL Backup will need to read from the transaction log to the LSN of the oldest active transaction for consistency. However, does the FULL BACKUP task write a minute amount into the log file to note that it's happened / happening as well?

Error from the Ola Log:

Date and time: 2017-03-13 21:30:40
Command: BACKUP DATABASE [DB] TO DISK = N'M:\Folder\file.bak' WITH CHECKSUM, NO_COMPRESSION 

Processed 1579192 pages for database 'DB', file 'DB_dat' on file 1.

Processed 855886 pages for database 'DB', file 'DB_log' on file 1.

Msg 9002, Level 17, State 3, Server SERVER\INSTANCE, Line 1

The transaction log for database 'DB' is full. To find out why space in the log cannot be reused, see the log_reuse_wait_desc column in sys.databases

Msg 3013, Level 16, State 1, Server SERVER\INSTANCE, Line 1

BACKUP DATABASE is terminating abnormally.

Outcome: Failed

Duration: 00:13:19
Sean Gallardy provided the information that led to the answer when he commented about the Backup forcing a Checkpoint:

Paul Randall Blog on Checkpionts