this post was submitted on 16 May 2025
30 points (89.5% liked)
Selfhosted
59973 readers
403 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:
-
Be civil: we're here to support and learn from one another. Insults won't be tolerated. Flame wars are frowned upon.
-
No spam.
-
Posts here are to be centered around self-hosting. Please ensure it is clear in your post how it relates to self-hosting.
-
Don't duplicate the full text of your blog or git here. Just post the link for folks to click.
-
Submission headline should match the article title.
-
No trolling.
Resources:
- selfh.st Newsletter and index of selfhosted software and apps
- awesome-selfhosted software
- awesome-sysadmin resources
- Self-Hosted Podcast from Jupiter Broadcasting
Any issues on the community? Report it using the report flag.
Questions? DM the mods!
founded 3 years ago
MODERATORS
you are viewing a single comment's thread
view the rest of the comments
view the rest of the comments
If you are going to store important data I would get a new drive. Either replace the internal or attach an external.
Also make backups.
I’m going to attach some used hard disks and ssds, I have many spare ones. I wanted to set up a RAID2 or 3, so even if some disks dies it’s not the end of the world.
RAID isn't backup, or even redundancy, it's for creating large storage pools. It's at the mercy of the controller and all the hardware. In fact, the more disks you have, the more likely you are to be impacted by a failure.
In a typical RAID 5, if one drive fails, the entire array is at risk until the drive can be replaced, and resilvered. During resilvering (rebuilding the drive with all the data it should have, parity, etc), the entire array is at even more risk because of the load on the other disks.
With dual parity and hot spare (less data storage total), you get a little more security since the parity is doubled and the hot spare will be automatically resilvered if a drive fails, but that's not without similar risks during that process.
You still need backup.
Here's a real-world example of RAID risks. I have a 5-drive NAS with 5 1TB drives, which gives me roughly 4TB of usable space (1TB parity). It runs software RAID using ZFS (a highly resilient file system, that can build arrays using varying disk sizes, and has some self-healing capability). I've had a drive go bad, replacing took 30 hours to rebuild. During that time, the entire array is "degraded", meaning no parity protecting the data because it's currently rebuilding the parity. If another drive were to have failed during this read/write intensive period, I would have lost ALL the data.
To protect against this, I have 2 other large drives which this data is replicated to. And then I use a cloud storage for backup (storj.io).
This is a modified version of the 3-2-1 method that works for my risk assessment.
Without offsite backup, you're always at risk of local issues - fire, flood, etc. Or even just a massive power spike (though that's not much of a risk, especially if you use a UPS).
I'm actually building a second NAS to have easier local redundancy, and because I have a bunch of drives sitting around. With TrueNAS or Unraid, it's pretty easy to repurpose old hardware. Though power is always a concern, so I'm looking for an inexpensive motherboard that has low power draw at idle.
Thank you for the comment and explanation. I was hoping for comments like this from people much more knowledgeable than me on this. The dual NAS thing is really not a bad idea.