RandomFactoid

Hi, yesterday I migrated from Truenas Scale to Unraid and am absolutely loving it so far, however things started getting a bit sketchy today. My setup: Microserver Gen8/Xeon E3-1260L/12GB ram/2x 4TB WD Red/1x 250GB SSD Whilst using Truenas my both 4TB drives were in a ZFS pool (mirrored). During migration I used the Unraid ZFS plugin to mount the whole pool, tried offlining one drive(Drive1) and checked whether I can still access the online ZFS drive (Drive2), which I could. I then formatted drive1 and manually copied approx 2tb of mostly media from Drive 2 to Drive1 which was the only drive in the array. I then 'destroyed' the zfs pool and set drive2 as my parity drive, letting unraid do parity rebuild/sync. It's been running for approx 6, however I started getting read errors (approx 30000 at the moment) in Drive1 (the one in array). It did slow down substantially at that point (from 130MB/s to kilobytes), however currently it's still running at a decent, but slower speed (~90MB/s). I will let it finish, however I have a feeling something's trying to break - I'm just not sure how far from breaking that 'something' is. My SSD is set as a cache drive. After it finishes sync'ing, how do I proceed ? Some pointers to diagnose the issue would be much appreciated. For now I have stopped the dockers i've set up and am just letting it finish building parity. Thanks