What is the ideal backup strategy for RAW files?

Photographers should always backup their photos using their camera's RAW file format. Any photo editing should ideally occur on a computer with duplicate hard drives in RAID 1 or a SSD, otherwise unaltered photos should be backed up immediately after capture. RAW files should either be converted to the DNG format prior to archiving or saved in their native format. When possible, edited versions of photos should be stored as processing steps (such as in XMP catalog files) as opposed to separate TIFF files. Each batch of photo backups should be written to at least two media, and all images should be stored along with SFV or MD5 checksum files and parity information, just in case a repair is needed. Each set of backups should be stored in a different physical building. Archived RAW or DNG files should be converted to some other format every 3-5 years to maintain software compatibility; each of these backups should be on new media using the latest storage technology to keep their data fresh. Source (Cambridge in Colour)