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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Acronyms, initialisms, abbreviations, contractions, and other phrases which expand to something larger, that I’ve seen in this thread:
Fewer Letters More Letters NAS Network-Attached Storage PCIe Peripheral Component Interconnect Express RAID Redundant Array of Independent Disks for mass storage SSD Solid State Drive mass storage ZFS Solaris/Linux filesystem focusing on data integrity
5 acronyms in this thread; the most compressed thread commented on today has 15 acronyms.
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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.
You won’t be using a traditional RAID with TrueNAS Scale. You have a choice of Stripe, Mirror, RAIDZ1, RAIDZ2, RAIDZ3, dRAID1, dRAID2, dRAID3. The docs are very detailed, so you should read up on RAIDZ and the other types elsewhere, too.
That is a way too broad question to be answer here and also depends on the file-system truenas uses.
If I remember correctly it uses ZFS by default and you can easily find some articles explaining the different raid levels of OpenZFS online.
Edit: ZFS is not the same as other file-systems so not all of the general RAID info you can find online is 1:1 applicable for it (same with btrfs).
0: “i don’t care about my data.”
1: “i REALLY care about my data”
5: “i’ll trade you one drive now, for my data if one of the drives dies later”
this is what chatgpt is made for
