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I recently got a few (5) hard drives to turn my home server into a NAS with trueNAS scale and my idea is to have 4 usable and 1 for redundancy, my question is... How does RAID work, like what is RAID 0, RAID 5, software RAID etc, and does any of that even matter for my use case?

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[–] [email protected] 11 points 11 months ago (7 children)

If you're using TrueNAS it already has some types of RAID it wants to do. Assuming your 5 drives are the same size what you want is called RAIDz1 (1 standing for one drive worth of redundancy).

It is a type of RAID5, which means instead of having 5x usable storage you reserve 1x for redundancy information spread out across the 5, and get only 4x usable space.

Since you're a beginner you get the usual lecture: RAID is not backup. RAID allows a certain number of your drives to fail without losing any data; it spreads the risk of hardware failure.

RAID won't help if you delete a file or accidentally explicitly format the wrong drive or even the whole array, and won't help if the PC is stolen or struck by lightning or burns in a fire.

The solution used by TrueNAS (ZFS) has something called snapshots that can help with modified or deleted files.

For anything else you have to consider which of your files are "my world has ended"-level of important and backup to a HDD in a drawer, or to Blu Ray discs, or online to the cloud.

[–] [email protected] 2 points 11 months ago* (last edited 11 months ago) (5 children)

Thanks, and yes, the disks are all the same, speed, capacity, brand etc... I'm confused about the difference between RAID 5 and RAIDz1, they seem to do the same thing on the surface and looking at the other comments and online, one of them is probably what I'm gonna go for. The only thing I get about the 2 is that RAIDz uses ZFS and RAID 5 does not (?)...

My "NAS" is relatively powerful and read/write speeds aren't really a big deal for me, as it's gonna be bottlenecked by the 1GBPs connection on my "NAS" (a PC I've scrambled together from handouts and cheap parts over the years)

[–] [email protected] 2 points 11 months ago (2 children)

RAIDz1 is just the ZFS version of RAID5. Since TrueNAS uses ZFS, RAIDz1 is what you'll be using (or RAIDz2 if you want an additional disk's worth of redundancy at the cost of a disk's worth of storage).

RAID5 isn't applicable to your situation. You'd have to be using a different OS, with a different default file system, for that question to matter.

What's the difference between RAIDz1 and RAID5? It's complicated. Without getting into the underlying specifics of how ZFS works, in short they're two different ways of achieving the same goal. To the end user, the differences are immaterial.

As an aside, if you're going to be using TrueNAS, which relies on ZFS for its storage technology, you're going to want to check if your disks use SMR or CMR. See this post for details; https://www.truenas.com/community/threads/WD-SMR-iX-Statement/

[–] [email protected] 1 points 11 months ago* (last edited 11 months ago) (1 children)

smr drives are horrible. we have some here. some by accident, others for cost savings (used only for long term, large file storage)--but all of smr's faults are really not worth it.. maybe at half the price per tb it might be--for some use cases, but not at current pricing.

the last batch we got in don't even support trim, so i guess the only way to 'clean up' zones is to literally dump everything off, secure_erase them, and 'start over'.

[–] [email protected] 1 points 11 months ago* (last edited 11 months ago)

TRIM is SSD technology and SMR is spinning-disk technology, you wouldn't find them on the same drive, would you? 🤔 Or do you mean a hybrid drive?

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