Also i know some basics on raid but I’ve only ever messed with raid0 with usb drives on a pi. I have 8 bays but 2 are currently vacant. What is the process of just adding an extra drive to a raid, or replacing one that already exists?
It depends on your RAID controller (or software RAID). I use hardware RAID (on Dell and HP servers) as it’s easy and a known technology, although these days people seem to be anti-HW RAID a bit.
When replacing a drive, you just eject the old drive, wait a few seconds put the new drive in, and most HW RAID controllers will start automatically rebuilding the array. Make sure your controller and drive bays support “hot swap” first! With HW RAID, replacing drives is great, because you can increase the capacity over time, because you can replace each drive with a bigger model, and once the last drive has been swapped over, you can expand the array and start using the extra capacity without having to move data around. With HW raid, most servers have an “Out-Of-Band” system (iLO, iDRAC, IPMI) which you can configure to alert you if a drive has died (or is about to die).
I would recommend keeping at least 1 spare of the same model HD of whatever you use, just in case.
I got burned by having a WD drive fail, and WD were being assholes about sending me a replacement (it was under warranty). Before I got the replacement, another drive started dying, and I couldn’t afford to buy another drive. In the end I lost 12TB of data 😭
And re the above - “RAID is not a backup” :) plan accordingly…
For software RAID, most Linux OSes support it automatically. I only use it as it’s easy to expand partitions (most of my Linux machines are VMs on a system with HW RAID).
This might be a useful article https://www.howtogeek.com/40702/how-to-manage-and-use-lvm-logical-volume-management-in-ubuntu/ (with a link to a previous one which is an introduction), which explains a bit about SW RAID.
ntfy is great!