Stefan Monnier wrote: > Michael Stone [2026-07-31 10:57:08] wrote: > > As others have suggested, a small array on consumer hardware is much > > more useful as a raid 1 than a raid 5. > > I'd even say that raid 5/6 is very rarely the better choice. In a sense > it's mostly of academic interest; in practice it's almost always > preferable to stick with raid 0/1/10. In theory raid 5/6 can be a few > percent cheaper in some cases, but it's rarely a good tradeoff. > So unless you really know what you're doing I'd recommend to stay away > from raid 5/6.
It All Depends, and economics vs performance is a real consideration. What can they buy for, say, US$1000, assuming that they have a computer capable of handling anything? One 8 TB M.2 NVMe SSD - very fast. No fault-tolerance. Takes up to 30 hours to be copied to other internal storage for backup. Three 4 TB SATA SSDs - moderately fast. Can be arranged in triple mirror (RAID 1) for excellent fault-tolerance but only 4TB of space, or performance can be traded off to get 8TB of storage in RAID 5. This is significant. Five 2 TB SATA SSDs - can be faster than three. Choices include: 2 x 2 stripe over mirror plus spare, for 4TB of space and amazing fault tolerance; RAID6 for 6TB of space and very good fault tolerance but less performance. Two 1 TB SATA SSDs and four 6 TB SATA spinners, arranged as a mirror pair of SSDs (fast, 1TB) and a stripe-over-mirror quad (fast for rotating media, 12TB). There are a lot of situations in which I would prefer this to any of the others above. A lot of these are artificial constraints by the current price of storage and the specific budget, but we always have these as actual constraints. The point is that there can be situations in which having bigger storage, or faster, or more fault-tolerant, is the primary consideration, and that leads to different choices. -dsr-
