Cost Analysis Of RAID1m Vs. RAID1
The cost of the controller coupled with its performance in write mode vs. RAID1 makes it a questionable purchase. The Vasstek provides "Quasi-RAID1" and opens up the option of a 1.5 GB SATA port; but even if you don't have dual SATA on your motherboard there's a bevy of other controllers available. One can buy two-port SATA II cards supporting RAID 0/1/5/10 or JBOD configurations for about the same price.
Sample calculation for 200 GB net space under RAIDm1 vs. RAID1:
Controller 30$ + 400 GB Drive $113 = $143 Total
200 GB Drive 2x $58 = $116 Total (Cost analysis assumes SATA ports native to Motherboard)
Conclusion
The price of the controller runs you around $30 and allows you a little more confidence in running an error-free, single-drive solution.
The card prevents the loss of your data by warning you before you reach the "bad clusters" stage, but it can also let you live in a fool's paradise. The biggest dangers for data loss are when the user inadvertently deletes files and failures relating to the physical component of the disks themselves. As more data is stored, the probability of loss becomes greater as writing/re-writing increases the chance of damage to disk particles. If you already make regular backups, this controller can help you identify potential problems/issues and allow for the calculation of MTBF before losing your actual work.
The mirror process afforded by RAIDm1, while allowing a backup system on a single drive, requires users to halve the storage space of their volume. If you get a lot of errors, you can't change your drive like you could with in a genuine RAID1 environment. While RAIDm1 could be an improvement for most users not already utilizing any RAID backup, creating copies of the volume becomes problematic. One has to clone their original RAIDm1 drive to another physical drive before duplicating the RAIDm1 from this cloned master. This method is not very user friendly or efficient.
If clients require "real security" they should migrate to RAID1. Most motherboards already ship with an integrated RAID 0/1 controller and would represent no increased cost other than the purchase of an additional drive. The read performance and dependability of a RAID1 solution increases exponentially with the number of drives added to the array instead of reliance upon a single drive for both data and mirror.
RAID 1 is a better choice for uninterrupted workflow, but if users aren't already utilizing RAID and don't have an additional SATA slot, the PCI 6153S may represent a viable option for more security.
Author's Opinion
I don't think the controller is worth buying. I'd stick with a RAID1 mirror as the cost per GB is less, and if you plan your purchase around it, you've probably already got everything you need right on your motherboard. If not grab a SATA II card using the same PCI form as the Vasstek and you're off to the races.
