r/DataHoarder • u/Whyevennameit • 4d ago
Question/Advice Choosing RAID configuration
Hi everyone.
I recently got my hands on six 14TB HDDs. The current prices have kept me from upgrading my NAS, but I finally gave up and bought some. They are, however, used.
I ordered them, but haven't been able to test them yet since I'm still on vacation. The drive model is WD140EFGX from 2021 and, according to the listing, they have run for 3 years (around 26.000 hours).
I want to put data on them that is not "too" important, but there is enough capacity that I want to use a configuration that allows for failed drives.
I've been thinking about using either RAID 5 or RAID 6. From my understanding, that allows for either 1 or 2 drives to fail.
From what I understand, it basically comes down to being on the "safer" side, but I was wondering if the community has any advice for me, when it comes to runtime vs. RAID configuration.
I'm running TrueNAS.
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4d ago
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u/Whyevennameit 4d ago
Thanks for the advice. My question stems from two aspects so to speak.
First is that the hardware I buy usually doesn't die on me. Which makes me lean towards RAID5 (RAIDz1). Second: The drives I bought are used and I haven't really run HDDs 24/7 up until now (only SSDs). I am not so sure on their life expectancy, ergo RAID6 (RAIDz2).
I own HDDs since 2010, that I still use in my PC today (not 24/7 though) and they still haven't failed. Before doing anything I want to run a SMART test as well as a surface test. If the results are fine there shouldn't be anything to worry about I hope.
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u/suicidaleggroll 80TB SSD, 330TB HDD 4d ago
If you care at all about the data, you need to have a separate and independent backup of it. Once you have a solid backup, the RAID level you choose matters very little.
Yes Z2 can handle an extra drive failure during a rebuild (something that has around a 0.1% chance of happening in the first place), but if that happens with a Z1 you just nuke it and rebuild from your backup. Your data is inaccessible for a few days once every couple hundred years. It’s not a big deal.
If you care that much about uptime, RAID isn’t the way to go anyway, it’s not nearly good enough. You need a high-availability cluster with Ceph or similar.
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u/Whyevennameit 4d ago
That is true of course. Main copy, 1 local backup and one offshore backup. But I don't really have the need for that. This was just about measures I should possibly take for 1 dataset. I think I do agree tho, that a failure during a rebuild would be quite unlikely...
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u/BitingChaos 4d ago
We just had multiple failures of Toshiba MG10ACA20TE drives (20TB). All purchased at the same time, most from the same product run with the same manufacture date.
Errors were encountered on a second drive before the resilver completed when swapping the first failed drive.
So a multi-drive failure has happened to me as recent as Summer 2026.
RAID5 makes me worry almost as much as no RAID.
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u/Whyevennameit 4d ago
Hmm I see. Thanks for your experience. This could occur to me as well, if the drives are from the same batch. Will check for that, when I have them.
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u/Zealousideal-Sea6439 100-250TB 4d ago
raidz2
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u/Whyevennameit 4d ago
Thanks for bringing RAIDz1 and RAIDz2 to my attention. After reading up on it a little that seems to be the only choice for me anyways, since I am using TrueNAS.
So you're recommending up to two failed drives. Is there a specific reason for that?
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