Scsi raid 5 has changed a little bit since the newest i960 pci controller and raid hashing cpu has accelerated. The disadvatange of raid 5 on the write was the hashing of the xor information for the raid 5 ecc algorithm. It should be faster than raid-3 in write since you are not limited to one disk performance as raid-3. We are currently running many db on raid-5 system and they work flawlessly running at over 10 to 50 megabytes per second (depending on the server hardware. The fastest being a compaq alphaserver gs160) Raid 5 is fast if you have a hardware processor to do the hashing. Most of the latest scsi raid card use the intel 960 cpu and some ata raid card (adaptec aaa-udma use a hardware cpu for hashing). Raid-3 is also slowly removed from the option of hardware raid controller. The latest from dell perc3 controller does not have the options to make raid-3. It is raid-0, raid-1 and raid-5.
As for serial ata. it is already replaced by serial ata2. It will support commang queuing just like scsi. It will also support hot swap. It will also support switches so you can cluster the 4 interface of the board (which are supposed to run at aroung 150megabytes per second at introduction) and connect more than 4 drives on it. It is becoming more scsi than it is ata.
Their was an image at comdex about a dell 2550 with a devellopement promise serial ata raid card connected to the hot swap bay on the 2550. Their was 4 drives running each on their channel. Their was also a demontration of serial ata switch.
As for ata raid. I am currently running 2 quantum fireball as. their is 1 advantage in file copy and the other one is lower load time for apps and games. Running the game server. it does make a difference in the load time for the next map or the next chapter of the game
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