Posting this here in case anyone else runs into these issues, hopefully it will save some time.   TLDR: Avoid using Crucial SSDs in your Unraid system. If you are using them, backup all the data immediately, consider replacing them, or at the very least check your firmware version and update to the latest (M3CR046) ASAP.   I had a cache pool using 2x Crucial MX500 1TB SSDs. They worked fine for about a year, but this past week I suddenly started getting all kinds of BTRFS err