I’ve recently had an issue where my differential backups are being converted to full backups (Using the Ola Hallengren Scripts) Ola does this to preserve your LSN Backup Chain. When a new Full backup is taken Ola’s Scripts are intelligent enough to see something else had taken the backup, and it knows for you, that if you were try to take a differential backup, you would run in to problems trying to perform a restore in the future. so it converts your would be Diff backup to a Full backup to keep YOU safe…
Bloating…
Now if something else, is performing full backups every night, you run into the situation where every Diff is being converted to a full backup, resulting in a bloated backup directory. Typically, it’s 3rd party backup software that is doing the job for you.
Point of fact: I would always recommend using SQL Server Native backups. That’s not to say 3rd party backup software is bad, I’ve worked with CommVault in the past and it does make managing an estate of 300 Servers easier… but it needs to be setup and configured correctly to work effectively. I Would also recommend regularly testing restoring your databases (to a test system) on a regular basis to confirm RPO/RTO & backup integrity .
Anyway!…….
How can I confirm what is backing up my databases from SQL Server?
Well, this SQL Script;
select bs.media_set_id,bs.database_name,bs.backup_start_date,bmf.physical_device_name,bmf.device_type
from backupset bs
join backupmediafamily bmf on (bs.media_set_id=bmf.media_set_id)
where backup_start_date > getdate()-1 and type=’D’ and database_name=’DATABASE_NAME’
You will notice, your regular backups will be using the SQL Agent User Name (Another good reason to have your SQL Agent using it’s own service account), and the Physical_Device_Name will be your known backup file.
Other entries, could be anything; Check for the Device name and the UserName. The Device_Type (7) means Virtual, this is a trade mark for 3rd party backup applications. these should help you pin point what other application is backing up the system for you…………. feed this information back to your Infrastucture/Server Engineers and get them to either stop, or get them to change the backup type to Copy_only.
Copy only backups do not interfere with the LSN Chain.