You may see this error message when trying to backup log from a database administrator or developer who interacts with SQL Server. It represents an error whereby the log backup would fail as this database lacks a full backup.
I will tell you how to avoid this mistake and how you can fix it if you already have made such an error.
SQL Server uses two types of backups: full backups and log backups. A full backup consists of all the data and objects in the databases, but a log backup only has the changes that took place since the last log or full backup. Log backups can be valuable for point-in-time recovery purposes, which enable you to recover your database in a given instance.
Nonetheless, log backups are based upon full backup. A full backup is a prerequisite for the log backup. The log backup has to keep track of when the log sequence started, and this information is stored on the full backup. A transaction log uses a unique identifier called the LSN that denotes the sequence or order of transactions. With this in mind, log backup cannot take place without full backup since it knows no beginning nor an ending point.
To avoid this mistake, ensure that your backup plan contains full backup as well as daily log backup. One possible solution is, for instance, to do a full backup only once per day while doing log backups every hour or even every quarter of an hour in accordance with your RTO targets. Hence, you will have a continuous full backup that sustains log backups.
With SSMS, T-SQL, or PowerShell, you can create and schedule your backups. Alternatively, there are third-party applications and services which provide much extended advanced capabilities and enhanced customizability. Whatever way you decide, ensure that you validate your backups and that they are kept safe but within easy reach.
This error occurs when attempting a log backup before a full backup. Ensure that you do a full backup of your database as fast as possible to correct this error. This will provide the initial benchmark for your future log backup and get rid of the error prompt.
But note that doing a full backup breaks the log chain if you had earlier log backups. Thus, you will not use those log backups to rewind your database to a point in time before the complete backup. Thus, you will first need to revert to their initial state by restoring the original full backup and then reinstalling the subsequent log backups. Hence, you should always attempt to make a full backup only when it is the least alternative possible.
Here, I have demonstrated that if you want to conduct a log backup but you don’t have a full backup, you will see an error saying, “Backup log cannot be performed because there is no current database backup”. I provided a reason as to why this error happens, its prevention, and the implication of rectifying it. I hope it has provided you with useful information regarding SQL Server Backups and perhaps some knowledge.