1. A method for execution by a processing module in a distributed storage (DS) unit, the method comprising: receiving a request to retrieve data; identifying a set of redundant array of independent disks (RAID) data blocks and corresponding RAID parity blocks that correspond to the data within RAID memory; when the set of RAID data blocks is error-free or includes correctable errors: retrieving the data based on the set of RAID data blocks; and outputting, via a communication interface of the DS unit, the data based on the set of RAID data blocks; and when the set of RAID data blocks includes more errors than are correctable based on the RAID parity blocks: retrieving the data based on a backup copy of the data from a dispersed storage network (DSN) memory by: retrieving a decode threshold number of error coded (EC) data slices of a set of EC data slices from the DSN memory, wherein a data segment of the backup copy of the data is dispersed error encoded to produce the set of EC data slices; reconstructing the data segment of the backup copy of the data using the decode threshold number of EC data slices; and reconstructing the backup copy of the data using the data segment; and outputting, via the communication interface of the DS unit, the data based on the backup copy of the data.