My cold storage NAS with 12 old HDDs (400GB to 1TB) acts as my btrfs test-env. It's all old hardware: Disks are salvaged from the company [after being shredded]

My cold storage NAS with 12 old HDDs (400GB to 1TB) acts as my btrfs test-env. It's all old hardware: Disks are salvaged from the company [after being shredded], the system is an Athlon Dual Core 5000+ on some MoBo with 4 SATA ports; no ECC, recently replaced the LSI 8 disk SAS controller with a 3ware 9560 12 disk variant (both as JBOD). No problems in the past few years, though it's only seeing a few hours uptime per week. It just acts as backup for data stored elsewhere, so a crash would be annoying, but not fatal - but I'm contemplating getting some new 4TB disks (now that I have a suitable controller) and putting a Plex on the thing.