SQL Server在完全恢复模型的数据库集中进行事务日志备份有哪些要求？

Question

I have implemented Ola Hallengren's maintenance solution and transaction log backup is running every hour. I was going to perform restore test for one particular database today and noticed that although the database is in Full Recovery Mode there have been no transaction log backup taken. There were about 100 other databases running on this particular instance and about 95 of them had transaction log backups successfully taken.

I have just recently taken over this environment so I have no history as to how things have been set up or how these databases have been created.

When comparing the settings I against a database which was getting transaction log backup taken I see that the "Log Reuse Wait Description" is set to DATABASE_SNAPSHOT_CREATION for the database that does not have transaction log backup but LOG_BACKUP or NOTHING for those having successful transaction log backups taken.

I checked backup history and those that had transaction log backup today had history of successful backup last months but there was no history of any transaction log backup being taking for the databases that I am not seeing transaction log backup. I also checked and there are no long running transactions going on.

1. What should I check and how should I fix it so that the log backups start to generate for all the user databases?
2. And is there something I can do to prevent this from happening in future?

Thanks in advance!

Answer 1

When you restored the last full backup, the database was in simple recovery mode. Databases in simple recovery mode do not use transaction log backups. In order to do transaction log backups you need:

1. Database in Full Recovery mode.
2. At least one full backup after switching to Full Recovery mode.