Abit kt7-raid

Abit kt7-raid

Abit kt7-raid - Setting Up A RAID Array + KA7-100

RAID was first devised for the computer industry to solve the need for faster, more reliable disk drives in business and scientific computer servers. RAID stands for Redundant Array of Inexpensive Disks and the idea came about as a cost effective way of increasing the reliability, speed and availability of data storage. Rather than developing a much much more expensive super-reliable super-fast disk drive it was realized that it would be cheaper to use two or more normal disks in parallel. The idea was first conceived by researchers at the University of California at Berkeley in 1987.

In fact, there are several levels of RAID offering different features. There is also single RAID and multiple RAID. The different single RAID levels are:

RAID level 0, or striping - is for speed. Data is split into blocks that are then stored on two or more disk drives. Reading and writing data can then be much faster as several drives do the reading and writing in parallel.

RAID level 1, or mirroring - is for reliability. Data is written simultaneously to two separate disks, one thus mirroring the other. If either disk fails the other automatically continues to provide the data. There may be some speed benefit as well, as the RAID controller can read data from the disk whose head is closest to the desired data block.

RAID levels 2-7, use parity - for reliability and speed. Rather than have 50% redundancy as with RAID level 1, several disks are used. If there are N disks then for every N-1 bytes of data an additional Nth parity byte is generated. These N bytes are then distributed across the N disks. If one disk fails its data can automatically be recreated using the parity byte. This is much more efficient than the RAID level 1. The difference between levels 2 to 7 is how this parity concept is implemented. Most use a separate parity disk, but this represents a bottleneck, and so RAID-5 tends to be the most popular mode as it spreads the data and parity blocks across all disks.

Multiple RAID involves the simultaneous use of two of these RAID approaches at once. This obviously requires yet more disks. Common forms of multiple RAID include:
RAID level 0+1 - for reliability and speed. This typically requires at least two disks to implement RAID-0 and the same number of disks configured as another RAID-0 array to mirror the first.
RAID level 0+3 and 0+5 - for reliability and speed. Here a combination of striping and parity are used.
RAID level 1+5 - for reliability. Here both mirroring and parity are used for highly reliable data storage.
As you will have guessed by now, RAID is a complex subject and my few lines above have hardly scratched the surface. For a true excellent guide see the article on RAID at PCGuide.com.

RAID on the ABIT KA7-100 and KT7-RAID

RAID on the ABIT motherboards is provided courtesy of the integrated Highpoint HPT370 controller. This low-cost IDE controller not only supports ATA/100 disks (as well as the slower speeds), but also the following RAID implementations:
RAID-0 - striping
RAID-1 - mirroring
RAID-0+1 - striping and mirroring
Spanning Spanning simply refers to the concatenation of two disks to form one larger disk. There is no striping or mirroring of data and hence no improvement in performance or reliability. It simply allows you to pretend your two (or more) disks are one big disk.

BIOS and Driver Issues

To use the RAID capabilities of the Highpoint controller you require two things: the Highpoint BIOS and the Highpoint driver for Windows. At the time of writing Highpoint do not provide RAID drivers for Linux.

The Highpoint BIOS is actually embedded within the motherboard BIOS and hence to get the latest Highpoint BIOS you must upgrade to the latest ABIT BIOS. For the KA7-100 you will probably have to use a BIOS provided by Yasin Abbas, who is kindly providing the service of embedding the latest Highpoint BIOS into the latest KA7 BIOS - ABIT don't seem to be bothering! For the KT7-RAID you will usually find the latest BIOS in the beta section of their ftp site. Either way, you'll always find the latest information and links to these BIOS's in the BIOS sections of Paul's KA7 FAQ and KT7 FAQ here at Apu's Hardware.

Disk Drive Requirements

To enable any form of RAID you require at least two disk drives. These should ideally be of the same size and speed. If one disk is larger than the other, the excess size of the larger disk is lost. Thus if you try to configure a RAID array with a 6GB and 20GB disk, the RAID controller will ignore 14GB of the 20GB disk - giving either a 12GB RAID-0 array or a 6GB RAID-1 array. A considerable waste! Likewise, if one disk is slower than the other, the controller will be forced to work at the speed of the slower disk. I recommend you buy a pair of identical disks.

As the Highpoint controller supports ATA/100 (or UDMA Mode 5) I recommend you buy ATA/100 disks for optimum performance.

WARNING: At the time of writing, the latest Highpoint BIOS is version 1.03 and the driver is 1.03b (beta). These versions, and all previous versions, seem to have serious stability and performance problems will Maxtor disk drives. Until these are resolved you would be well advised to purchase an alternative brand of disk - check the disk section of Paul's FAQs here for the latest news.

Connecting the Drives

For ATA/66 and ATA/100 disk drives remember you need to use an 80-way IDE cable. Without this, the controller will automatically revert to ATA/33 or slower. Connect the disks to the Highpoint IDE connectors (colored blue on the motherboard), ensuring the cable is connected the correct way round! If the cable has a blue connector at one end, this should be connected to the motherboard. If not, connect the connector which is furthest from the "middle" connector on the cable to the motherboard.

For RAID-0 you must ensure that the disks are located on separate IDE controllers. That is, one on the Primary controller and one on the Secondary. This allows the two controllers to work in parallel.

Creating a RAID Array

To create a RAID array on your KA7-100 or KT7-RAID you should perform the following steps. In the example below I have described the creation of a RAID-0 array: creating a RAID-1 array is very similar.
Flash to the latest motherboard BIOS (possibly a beta BIOS to get the latest Highpoint BIOS - see the BIOS section of the FAQ)
Backup all of your current data - the creation of a RAID array will destroy all the data on your disks! I advise you to unplug the ribbon cable from any other hard disks on your system which will not be part of your RAID array (this prevents you from accidentally formatting them).
Connect the drives to be used to the Highpoint controller as described above
Enable "Future ATA IDE Controller" in the Integrated Peripherals section of the motherboard BIOS, then Save and Exit.
Enter the Highpoint BIOS menu (using Ctrl-H) and use "Create RAID" to create your RAID-0 array. This is illustrated in Figure 1 below.

In the "Create Raid" menu, select the disks you wish to use, a Block Size of 16k for optimum performance in most situations and then choose "Start Creation Process". This is illustrated in Figure 2 below.

Reboot the machine using a bootable floppy disk which also contains the FDISK and FORMAT utilities (you will probably need to copy these onto the floppy as Windows doesn't put them onto bootable floppies as a matter of course). Type FDISK to start this utility. Using FDISK create the partition(s) you require - as a minimum you require one active Primary DOS Partition. Reboot your machine to activate the new partition(s) Type "FORMAT C: /Z:32" to format partition C: Repeat for any additional partitions you created. Note that the "/Z:32" parameter formats the disk with a block size of 16k - equal to that of the stripe size. This has been recommended as optimum.

Having performed these steps you have now created a RAID array which now appears to the system as a single drive. Under DOS or Windows 3.1 that's all there is to it - no drivers required. Under any Windows version later than 3.1 you will need to install drivers for the system to use your new driver properly.

So, on to installing Windows...

Installing WindowsME On Your RAID Array

This section describes how to install WindowsME onto your new RAID array. It really is very simple, as Windows will use a DOS compatibility mode (which can use the RAID array) until you install the Highpoint drivers. So, the steps to follow are:

Boot your machine from the floppy, with CD-ROM support enabled
Place your WindowsME installation CD in the drive and type "E:" then "SETUP" (assuming E is the CD-ROM drive) to start the Windows installation process
Once Windows has finished installation, immediately install the latest Highpoint drivers. Do this by going to My Computer, Properties, Device Manager, Other Devices, PCI Mass Storage Controller. Right-click on this, select the driver tab and then Update Driver. Specify the location of your Highpoint drivers and you're done.
Continue the installation of your software with the VIA 4in1 drivers and then other software, as described in the "How should I install the software for my new motherboard?" question in Paul's FAQs.

Note: SB16 emulation by your soundcard driver may conflict with the Highpoint controller resulting in the Blue Screen of Death (BSOD) when you reboot after installing the sound drivers. To avoid this, select "No" when the sound card driver asks whether to reboot the machine after installation - go into Device Manager, find the sound card driver, disable SB16, and then reboot.

Installing WindowsNT or Windows2000 on Your RAID Array

With WindowsNT or Windows2000 the Highpoint drivers are required right at the beginning of the installation process, as a DOS emulation mode is not used during the installation. After inserting the installation CDROM you should press F6 as soon as you see the message "Setup is inspecting your computer's hardware configuration". Then press "S" to configure an additional adapter. You should then insert the floppy containing the Highpoint drivers. After this, installation should proceed as normal. The Benefits of RAID-0 On my machine I have two cheap and nasty ATA/66 Seagate 8.02GB disks. However, I thought I'd give RAID-0 a try to see what difference it would make. To benchmark my system I used HDTach v2.61 and SiSoft's Sandra 2000. I obtained the following results - fairly average for an ATA/66 drive.

HD Tach reports a random access time of 16.3ms and a read burst speed of 42.8 MB/s. It indicates minimum, average and maximum read speeds of 11.29, 19.645 and 23.392 MB/s respectively.

SiSoft Sandra scores 12957 for this drive - very close to the average.

After RAID

After RAID we see significant improvements. The random access time is slightly lower at 15.1ms, but the read burst speed is significantly enhanced to 59.9 MB/s. The minimum, average and maximum read speeds are increased to 13.053 34.605 and 47.429 MB/s respectively. A definite improvement! The only downside is an increase in CPU usage from 3.6% to 10.3% - this is the overhead of "unstriping" the data.

SiSoft's Sandra shows a similar improvement from 12957 to 20319. Again, a very significant improvement over the normal result for an ATA/66 drive!

Summary of Results

So, in summary, the results were:
Measure Before RAID After RAID
SiSoft Sandra 12957 20319
Random Access Time 16.3ms 15.1ms
Read Burst Speed 42.8 MB/s 59.9 MB/s
Read Speed Min 11.3 MB/s 13 MB/s
Read Speed Av 19.6 MB/s 34.6 MB/s
Read Speed Max 23.4 MB/s 47.4 MB/s
CPU use 3.6% 10.3%
So, in conclusion a significant improvement all round! If you don't mind a slight increase in CPU utilization during disk access then this really does seem like the ideal way to improve your system for free - assuming you bought a KA7-100 or KT7-RAID to start with! Of course, there's not really any such thing as a "free lunch", so what you gain in speed you lose in terms of mean time between failures. If one RAID-0 disk fails you lose everything - so make sure you back up your valuable data!
Pro's: Con's
  • Significant disk performance increase with RAID-0
  • Increased data reliability with RAID-1
  • It's free! (If you already own a KA7-100 or KT7-RAID)
  • Increased failure rate with RAID-0
  • Loss of storage capacity with RAID-1
  • Increased CPU overhead
Final Thoughts: Cost effective way of improving disk performance or reliability
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