this post was submitted on 14 Dec 2023
31 points (84.4% liked)

Selfhosted

39937 readers
359 users here now

A place to share alternatives to popular online services that can be self-hosted without giving up privacy or locking you into a service you don't control.

Rules:

  1. Be civil: we're here to support and learn from one another. Insults won't be tolerated. Flame wars are frowned upon.

  2. No spam posting.

  3. Posts have to be centered around self-hosting. There are other communities for discussing hardware or home computing. If it's not obvious why your post topic revolves around selfhosting, please include details to make it clear.

  4. Don't duplicate the full text of your blog or github here. Just post the link for folks to click.

  5. Submission headline should match the article title (don’t cherry-pick information from the title to fit your agenda).

  6. No trolling.

Resources:

Any issues on the community? Report it using the report flag.

Questions? DM the mods!

founded 1 year ago
MODERATORS
 

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?

you are viewing a single comment's thread
view the rest of the comments
[–] redline23@lemmy.world 1 points 10 months ago (1 children)

Other people gave a good explanation of raid and some alternatives like zfs in truenas.

You want to avoid RAID5 with drives above 4TB. Every hard drive has can have an unrecoverable read error (URE) during the read. It's a very low percentage change that your hard drive publishes. During a raid 5 rebuild after replacing a drive, the other drives are stressed for a long time during the rebuild. With high capacity drives you have a pretty large chance of encountering a URE and losing the entire array. The high stress on the drives can also cause drive failure if another drive was on its way out.

I run truenas core at home in volumes that looks like raid 10. Two mirror volumes striped together for performance.

I never played around with raidz1 (like raid 5) but you still have the chance of an URE during the resilver. I can't comment if it's possible or what happens during an error. I did see people recommending raidz2 to allow for two disc failures from losing data during a resilver.

[–] Presi300@lemmy.world 1 points 10 months ago (1 children)

All my disks are 2TB so it shouldn't be a massive issue

[–] redline23@lemmy.world 1 points 10 months ago

I personally wouldn't use raidz1 because it seems too risky to me. I'd have higher redundancy.

Some links

https://www.truenas.com/community/threads/raidz1-vs-raid-5-ures.42598/

https://www.truenas.com/community/threads/5x-4tb-raidz1-array-rebuilding-with-nre-ure-issue.13719/

https://magj.github.io/raid-failure/

The last link is talking about actual raid and not zfs. But it has a 50/50 chance with a URE rate of 10^14 to lose the array. Raidz1 maybe won't have that catastrophic of a failure, but you'd still be rolling the dice on some corruption.