Other people gave a good explanation of raid and some alternatives like zfs in truenas.

You want to avoid RAID5 with drives above 4TB. Every hard drive has can have an unrecoverable read error (URE) during the read. It’s a very low percentage change that your hard drive publishes. During a raid 5 rebuild after replacing a drive, the other drives are stressed for a long time during the rebuild. With high capacity drives you have a pretty large chance of encountering a URE and losing the entire array. The high stress on the drives can also cause drive failure if another drive was on its way out.

I run truenas core at home in volumes that looks like raid 10. Two mirror volumes striped together for performance.

I never played around with raidz1 (like raid 5) but you still have the chance of an URE during the resilver. I can’t comment if it’s possible or what happens during an error. I did see people recommending raidz2 to allow for two disc failures from losing data during a resilver.