Who Makes The Best RAID Controller?

thonot asks: "I build PC's from my home, generally for frinds and friends of friends. Yesterday though, my wife's boss called me and asked if I could build him a bussiness PC. The only problem is that he wants a RAID0 configuration w/ 3 Seagate Cheetah 18.4 Gig 15k RPM SCSI drives, and I've never even seen a RAID controller, well except in pictures. Can anyone point me in the direction of a good controller card?"

Comments

Good experiences

[JediTrainer]

I've had good experiences with a couple of Mylex controllers as well as the Compaq SmartArray line.

With Mylex, you can get the controllers either as PCI cards for the box, or you can get one that comes as a big box (external controller).

The PCI version looks basically like a SCSI card, and is configured by software you get with it.

The external version is meant to be mounted in a separate tower with your drives. Often comes with its own memory and LCD screen and fun buttons to play with (and configure the array with). It has two (or more) connectors - one to the computer (entire array appears as a single SCSI ID) and one to the rest of the drives in their own SCSI chain. The advantage to the external model is that you only need to install the drivers for your SCSI card - the array requires no additional software. Disadvantage is that they require space in an external tower - often they are full height (2 bays).

With the Compaq beasties, you'd need the Compaq SmartStart CD that comes with their servers to configure the stupid arrays. Can't find the software on their site anywhere. But... they are good controllers and have never let me down.

One thing though - RAID 0 (striping) is a dumb configuration for business use. If any single drive dies, you lose all the information on ALL of them. RAID 0 basically chains the drives together to make one gigantic drive.

RAID 1 (mirror) offers you redundancy. One drive mirrors to another. But... that means you lose the capacity of one drive (and RAID 1 only supports 2 drives). If a drive dies, use the other one.

RAID 0+1 (stripe + mirror) for use with an even number of drives. Basically stripe as many drives together as you want, then mirror that entire array to another set of drives. You lose the capacity of half of your drives for the mirror. If a drive dies, you use the other chain.

RAID 5 is probably one of the most common configurations. Chain a few drives (most people do 3-5, but it supports more) and it distributes parity information throughout the array. If you lose a drive, you can replace it and keep going - no data loss. You lose the capacity of ONE drive in this configuration. Thus, it's less of a loss if you have 5 drives (20%) than if you have 3 (33%). It's perhaps not the fastest type of array around, especially for lots of seeks (it's fast for large files) - do not use RAID 5 for a database, for example.

All this being said, if all you need is striping (RAID 0), chances are that whatever OS you're using supports doing this in software quite nicely without much overhead at all. For example, NT and Linux both support software RAID 0 right out of the box.

If you MUST buy a controller, then Ebay is your friend.