RAID 5 was great, until high-capacity HDDs came into play, but SSDs restored its former glory.(+)
New tech becomes obsolete and forgotten at an astonishing speed. However, sometimes it’s enough to develop another approach and all the old technology may become relevant again. This happened to RAID 5, because HDD capacity grew, but spindle speed had mechanical limits, which eventually made RAID5 too volatile.
With modern high-capacity HDDs, RAID 5 became unreliable, because it remains in a failure-prone state for a long time. Seek speed remains the same, while capacity grows, so rebuild time grows as well. This means the risk of double failure and major data loss becomes higher by order of magnitude. Besides, Unrecoverable Read Error chance being 1 bit in 1014-1015, the risk of double failure is roughly 50%, which is a disaster.
Using SSDs renders RAID 5 immune to the reliability issues, because flash is faster, has aptitude for random dada access and usually come in smaller capacity. Interested how utilizing SSD renders RAID5 immune to parity RAID issues? Check out this article here https://blog.starwindsoftware.com/2015/10/26/heres-what-lsfs-wafl-casl-is-about-where-log-structuring-concept-came-from-what-its-good-for-and-why/