A storage system maintains copies of a source database to allow virtual databases to be provisioned. Transaction logs received from the source database are applied to database blocks stored in the storage system to update the database blocks. The storage system checks if there are defect in the transaction logs of the source database. If a defect in transaction logs is detected, the storage system obtains a latest copy of the source database. The storage system matches database blocks of the received copy with database blocks already available in the storage system to determine whether a corresponding database block is already available in the storage system. If a received database block is different from database blocks already available at the storage system, the received database block is stored in the storage system. The database blocks may be matched using a hash value of the database blocks.