To fix the issue, disable "Circular Logging"
- You have a full backup and several transaction log backups;
- You create one more transaction log backup;
- The transaction log backup fails with the following error:
The log file sequence is inconsistent. A hole is detected between log file numbers 243 and 469
Transaction log files (.log) store all changes made to an Exchange database or storage group. Before committing any change to a database file, Exchange logs the change into a transaction log file. Only after the change is securely logged, it is then written to the database. When an active log file is full, Exchange closes it and creates a new log file. A set of sequential log files is called a log stream. Each database or storage group has its own log stream.
A transaction log backup stores transaction log files along with checkpoint files. At first backup, Acronis Backup creates a regular full backup of the corresponding Exchange information store, storage group or database. After that, only the log files and checkpoint files are backed up. So any holes in log stream may affect transaction log backups. Circular logging or other backup plans (or other backup applications) may truncate the transaction log files. Log truncation will interfere with the consecutive transaction log backups.
It is not possible to run transaction logs backup with Circular Logging enabled. Circular logging must be disabled in MS Exchange, otherwise the backups will fail.
To turn off Circular Logging in Microsoft Exchange Server:
- MS KB: Microsoft Exchange Server 2003: How to turn on or turn off circular logging in Exchange 2000 Server and Exchange Server 2003
- MS TechNet: Microsoft Exchange Server 2007: How to Enable or Disable Circular Logging for a Storage Group
- MS TechNet: Microsoft Exchange Server 2010: Configure Mailbox Database Properties