Seeking Advice for Setting Up TrueNAS Scale on an Old Computer

TrueNAS General
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  1. You have to use CMR drives, SMR is known to cause issues (or to be incompatibile at all with ZFS).
  2. It’s best to stick to same sizes, and to distribuite the models depending on your layout: read the following point.
  3. ZFS does not use RAID. Read this and this.
  4. If you are not going to use new drives you want to really be sure the used drives you have are not toasted… and want to have considerable parity; about performance, you should set the datasets block size according to the files you want to store… and read point 3.
  5. Read point 3.
  6. Avoid cheaping out on the PSU and the HDDs. Read a lot… you can find things here.