We've got a SharePoint 2010 Farm (SharePoint server and SQL Server split) which should be backed up on regularly basis. First we had a SQL Backup (FullBackup in the evening, Differential every 4 hours), but we had the problem that with a 30 day history the backup drive gets too small. One SP-application has a full backup size of about 10GB, the differential is always around 8GB.
I tried the same with a copy of the farm, just there was nobody working on. Same results. Same with the Powershell SPBackup-command.
My question now: shouldn't the differential backup be quite smaller? Why is it almost the same size as the full backup?
Are there any different experiences?