MSP360 Backblaze B2 Replication Bucket Size The software applies its own retention policy exclusively to the storage destination specified in the backup plan settings. If your second bucket grows in size, it's likely because nothing is being purged from it. Additionally, it's important to understand that if you change the retention setting in the backup plan, the new setting will only be applied to new backups. All previous backups will retain according to the retention settings at the time of the backup.