Building Redundancy with a SATA RAID Array
A title like that might be enough to scare off some of the most interested do-it-yourselfers. But redundancy and speed is what RAID is all about.
The new SATA II hard drive controllers on many motherboards include some RAID functions, and add on SATA RAID controllers are relatively inexpensive. For example the Gigabyte GA-M51GM-S2G motherboard is a low cost all in one board yet it has RAID 0, 1, 5 and 10 built in.
Now I’m going to have to skip some of the basics here, since the format of Geek’s Corner doesn’t allow enough room for me to explain all about RAID, and all the variations thereof. I’m going to get right down to the “get’R’done” part that seems to stop many would be DIY’s. If you don’t know the difference between RAID 0, 1, 5, 10, 50, and 6 I have a little more detail in my article RAID, What is it and why do you care? Plus there is plenty of info available from a basic Google search.
Now for the purpose of this article, I will configure a Mirrored Array, (RAID 1). I can hear all you geeks out there moaning already “But I want to try out RAID 5”. Stop whining, once the array is configured, it is all the same. RAID 1 causes the same problems that RAID *whatever* causes, and it takes less time to explain.
First you will install your hard drives, and connect them to the controller card whether it is on the motherboard or a separate card like the Adaptec 1420sa. Make sure the drives are identical; you can use two different brands if they are the exact same size and speed, but it is a BAD IDEA, just get two new drives and make your life simple. If you are still reading at this point I’ll assume you can install them on your own. However, do pay attention to which ports you are connecting to, i.e. drive 0 and drive 1, or 1 and 2, etc. You’ll need that information later when you have to identify the drives in your array.
There are a couple of things that confuse first timers when setting up a RAID array. First of course is actually configuring the array, and second is you have to specify if the array is bootable in the controller card BIOS. When you set up a regular hard drive, the motherboard BIOS automatically makes it bootable, so that bootable array thing always confuses the beginner. If you’ve already installed software on the non-bootable array, just blow it all out and start again. Don’t try to save it.
It may also be confusing that the RAID controller has its own BIOS, regardless if the controller is integrated on the motherboard or on a separate card. So in every case you will be dealing with setting up two BIOS’. If you’ve purchased a controller without a BIOS, take it back, it can not be made bootable.
Configure the motherboard BIOS
OK. So first we configure the motherboard to boot from the array. This will be different on every board, but you will start in the motherboard BIOS (Figure 1). If the controller is NOT onboard, you usually will have to choose “Boot from SCSI” in the boot sequence and move on to the controller card BIOS. In the case of the GA-M51GM-S2G there is actually a choice to configure the motherboard to accept the configuration from the controller BIOS later. (Figure 2 through 4) In this case you select Integrated Peripherals, then SATA II Configuration, and in figure 4 you must enable the SATA II RAID Function (the controller BIOS won’t come up if it’s turned off), and then choose which controller channel you want to use and enable it (we’ll set SATA II Primary and SATA II Secondary to enabled in this description). Save your settings and let the system restart and go into the Controllers BIOS (figure 5).
Configure the Controller BIOS
If you are using a controller card, on a motherboard without onboard RAID, then you jumped to this section after setting the motherboard BIOS to "Boot from SCSI".
Now what we need to do is specify the RAID function we want, Mirror (Figure 6), and then assign the drives to be used by the RAID controller (Figure 7). Of course you may only have two drives at this point, but the controller would have allowed you to choose two out of eight if your system was set up that way. It is much easier with identical drives to only have the two you want to use installed during this process. If you have more then two drives, look at the LOC and pick the drives based on the controller number, and the connection number.
Once the drives are selected choose F7, finish, or if you are using a controller card follow the instructions to save the configuration. This seems so simple that you may blow by it, but at this point the system must flash the data back to the chip on the controller, so if you don't carefully save your work, you WILL do it all again. Make sure the RAID Mode doesn't change on you, some times it will switch from whatever you choose to the default or to another choice based on some miscue of the mouse or keyboard. I actually had a server come in for service a year after we built it only to find it has switched from mirroing to striping and the builder hadn't noticed. It took me all weekend to rebuild it properly.
You should get some warning screens telling you that you are about to delete all your data and so on but one this is saved and the system rebooted you are done.
You will need to make a driver disk on floppy to feed to Windows at the F6 prompt during set up or Windows won't recognize the drives, but that's for another months edition.
-Steve Weigle
See Also:
RAID, what is it and why do you care?