One or more of the hard drives in my QNAPS412 is dying. It's generating a lot more I/O errors. The system firmware is not picking up the bad sectors which means now is the time to start pulling data out of the NAS and wipe it clean.
Today I bought a Western Digital 6TB hard disk to swipe all the files out of the dying NAS as an interim.
My hardware troubleshooting and networking skills with NAS and server architecture is limited, so I'll throw money at proven solutions now rather than learn from scratch.
From this experience I've learnt that RAID arrays do not save me from catastrophic failures. If a disk is faulty, and I can't figure out which disk is in trouble from the firmware, then I'm in no better position than just using single volumes or JBOD. The performance with a RAID array is just not worth the trouble.
I'll use the simpler 3-2-1 backup method instead. Have three copies of important data, 2 on site (different mediums) and 1 offsite. So if I use kitten.jpg as an example: I'll have kitten.jpg in my main machine, a copy in local NAS1 and another copy in NAS2 off site. If i delete kitten.jpg from my main machine, then I'll need to create another copy locally, possibly in an external HDD.
My storage mostly contains high resolution photography RAWs and video files. Then comes the ISOs for games and video files of various multimedia. My vital stuff is already safe, but I don't really want to redownload everything in the array that is failing.
Still deciding whether to get the Synology DS416 and then outfitting it with 4x Western Digital 6 or 8TB Reds, or building a new PC and chuck a bunch of disks together with a slimmed down version of Windows Home Server. The costs are probably the same with one being plug and play, and the other with slightly more technical skills to configure.