Selfhosted

Hey welcome to the fun of multiple drives. If you have the drives available then truenas (which uses OpenZFS) is better IMHO than hardware raid as it is just more resilient and you can (most of the time) move zfs data/pools around easily. I'm guessing ye olde Dell has a Dell raid card, and whilst they are ok, zfs is way better nowadays. If you value your data then parity and mirroring make for way better usage of drive space if you are careful. I mean zfs easily can support losing a whole drive (or 2 if you wish) without losing data, and the rebuild speed is pretty much 10X faster than old dell raid cards IF a drive does fail. Truenas has some great features built in for backup etc. and a decent truenas setup is way more flexible than a lot of the cheaper pre-built nas boxes as well. Of course, your mileage might vary, but I wouldn't be without my truenas setup now. It also serves via shares to the android tv box for movies etc. I don't even bother with plex. Whilst you might keep a single drive as a backup of the backup that pretty much wouldn't be needed in zfs as the data is pretty damn secure with parity, but you might not agree. The other beauty of using zfs is that it is perfectly happy to use sata/sas/m.2 drives or whatever as long as they are accessed directly, though with an old dell raid card if it doesn't support it mode or pass through for the drives it doesn't work - zfs just needs simple access to the drive

Hardware RAID is dead.

• They're no faster than Software RAID today

• They're vendor and often model locked to a particular make or model of card (so if your card goes bust, so does your array, where software options you can migrate the entire machine to a completely new one, as long as the disks are good so is your data)

• ZFS wants access to individual disks anyway

Check which raid card your Dell shipped with, if it's a PERC H200 or H310, you can flash it to IT mode to make it work as a plain HBA. If it's a PERC 700, you're SOL on IT mode. I'm pretty sure it can expose vdrives, but that's probably more trouble than getting a cheap HBA at that point.

The safest and most flexible option would be to configure the BIOS to not use the RAID controller and just "see" the drives as a regular JBOD, and then setup a ZFS RAID-Z1 array and configure your zvols, etc. in that instead. RAID-Z1 is functionally very similar to old-school RAID-5. There's virtually no performance penalty with software RAID these days, and you're eliminating the proprietary RAID controller as a single point of failure.

TrueNAS (ZFS) needs direct access to the drives. Typically a software raid is considered to be more reliable/flexible since with ZFS it also checks for file integrity. You can set several variables to add to the integrity as well as special vdevs to help speed things up. Integrety comes at the cost of storage, so make a plan for how much storage you need versus how much data integrity you need.

Do not use a raid controller with Truenas. Use a HBA such as an LSI 9300 or 9207 (old but fine for HDD). Truemas manages the drive itself and any barrier to that (like device managed SMR drives and Rains controllers) means Truenas does not know where the data is, and you are likely to get data corruption at some point.

I'm glad I asked! Thank you all, I'll have to make some changes.