I have 3 servers, all with the same specs:
Intel CPU
8 GB RAM
Linux or BSD
Single 2TB desktop SATA with more than 10K Hours of operation, with only less than 300 GB Used
My provider cannot install a second hard drive, but can guarantee me that the drive will be replaced immediately in case of failure, with another equally crappy drive.
The likelihood of drive failure is high, and since I can't use RAID, I was thinking about keeping a back up of each machine on all the other machines, so that there are always 2 copies on 2 different drives, plus the original.
I would synchronize the drives every hour, with rsync, to guarantee some sort of redundancy, since bandwidth inside the DC is free, so it would be much cheaper than offsite backup. (A daily offiste backup is kept anyhow).
What do you think? Any suggestion?