I’ve got some Western Digital and Samsung HDDs I bought refurbished a while ago in a RAID10 configuration for 4 TB total. Recently setup backups to that and an SSD, the read/write speeds are slow but tolerable and I’m not doing anything that needs high throughput. For backups from multiple machines, it does the job and I make sure to upload the encrypted backups to remote storage once a month so if there’s any catastrophic data loss on my end it’s all recoverable.