Optical media, such as CDs, DVDs, or Blu-ray discs, are a suitable choice for backing up a large collection of DVDs and photos in the most economical way. Optical media are inexpensive, widely available, and have a long shelf life. They can store large amounts of data, up to 50GB on a dual-layer Blu-ray disc, and can be easily labeled and organized. Optical media are also less prone to mechanical failure, data corruption, or accidental deletion than hard disk drives (HDDs) or solid state drives (SSDs).

The other options are not as economical or suitable for this purpose. A 5,400rpm HDD is a slow and noisy type of HDD that has moving parts that can wear out or break. A HDD also consumes more power and generates more heat than an SSD. A M.2 NVMe SSD is a fast and compact type of SSD that uses a PCIe interface to transfer data. However, an SSD is more expensive than an HDD or optical media, and has a limited number of write cycles before it degrades. A SAS RAID array is a complex and costly system that uses multiple HDDs or SSDs connected by a Serial Attached SCSI (SAS) interface to provide redundancy, performance, or both. A RAID array requires a RAID controller, a compatible motherboard, and a dedicated power supply.