Despite what is often claimed, what is most important to virtually every computer user is not performance but rather data integrity and system robustness. To that end certain hardware is required: To protect data integrity from cosmic background radiation in RAM, ECC is recommended [Its worth the couple extra dollars] To ensure all disk writes occur a combination of both properly written software and a battery backed write-back cache on the controller and a write-through cache on the disk. Write-back cache on the disk will cause a demon of unsolvable write failures. For those who wish for more performance but still require data integrity, I'd recommend a SSD as the main storage and a proper raid 6 setup using only a write-back cache on the controller and write-through cache on the disks.
A UPS or a battery is invaluable when data integrity is required, since it gives one the time it takes to finish the task at hand and shutdown in a clean state. No software can compensate for the lack of these hardware basics, which cost only a fraction more.
