alt Hacker News> I'd not use RAID-5 for my personal homelab.
What would you use instead?
ZFS is better than raw RAID, but 1 parity per 5 data disks is a pretty good match for the reliability you can expect out of any one machine.
Much more important than better parity is having backups. Maybe more important than having any parity, though if you have no parity please use JBOD and not RAID-0.
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timc3 • last Saturday at 5:29 AM
I would run 2 or more parity disks always. I have had disks fail and rebuilding with only one parity drive is scary (have seen rebuilds go bad because a second drive failed whilst rebuilding).
But agree about backups.
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I'd almost always use RAID-1 or if I had > 4 disks, maybe RAID-6. RAID-5 seems very cost effective at first, but if you loose a drive the probability of losing another one in the restoring process is pretty high (I don't have the numbers, but I researched that years ago). The disk-replacement process produces very high load on the non defective disks and the more you have the riskier the process. Another aspect is that 5 drives draw way more power than 2 and you cannot (easily) upgrade the capacity, although ZFS offers a feature for RAID5-expansion.
Since RAID is not meant for backup, but for reliability, losing a drive while restoring will kill your storage pool and having to restore the whole data from a backup (e.g. from a cloud drive)is probably not what you want, since it takes time where the device is offline. If you rely on RAID5 without having a backup you're done.
So I have a RAID1, which is simple, reliable and easy to maintain. Replacing 2 drives with higher capacity ones and increasing the storage is easy.