I have to agree mostly with George. I think from what he said, he has a hot spare, so boom he still has a RAID5 albeit slower until it rebuilds. And, he gets an email, and boom he puts in the hot swappable, and now he can lose a drive again.
I think for data, you can't beat a RAID5, because you can get a lot more space by adding extra drives. I wouldn't worry about the power and heat can be dispersed using the correct fans and the right amount of fans. I would never use two servers and all of those issues when one server would suffice.
As to the OS, a RAID1 still has more redundancy and you suffer very little performance loss while it is having the other drive rebuild.
In a personal computer, if you want better performancy, then add as many drives in a RAID0 as you wish. With RAID1, you can only use two drives, which would have to be large to have more data. Now, of course, what we haven't talked about is striped mirrors as in a RAID10, which is an excellent setup.
If one were going to use one RAID on a server mostly used for data and databased with some applications, they would be better off using RAID5 or 6, although 6 just isn't used that much. RAID10 is a very good compromise for everything.
So, in summary, I would recommend a RAID1 using 10,000 RPM SATA drives such as the WD Velociraptors (these are nice) with a RAID 5 for data. If you can go with a RAID6 even better.
The deal is coupled with GOOD data backup you are all set. What George is saying is one can always set up the RAID1 OS with the disks, whereas the data has to have good backups and a good RAID.
RAID53 anyone?
