What's a good cheap home server / NAS with the sole purpose to act as a #backup server for #Linux and #Windows?
For Linux, I was thinking borg or similar deduplicating backup. For Windows, whatever achieves a similar goal. Should be small and quiet. Important data will have additional off-site backup, so the home server hardware can be cheap.
Is an old computer or Raspberry Pi my best choice? Standard Linux or some special OS? SSH or Samba or some web service on HTTPS?