Space Raiders

If you’re looking for an inexpensive disk solution that offers more data storage, top performance and security too, look no further. Windows gives you the scoop on RAID

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By  Cleona Godinho Published  March 1, 2006

|~||~||~|RAID (Redundant Array of Inexpensive Disks) refers to a system of combining two or more hard disks to offer more data capacity or a second copy of important data. There are many advantages to using this, which differ depending on the type of RAID you choose. For instance, if you want red-hot performance, RAID 0 will do the trick, whereas if you want to keep your data safe from crashes or data corruption, a RAID 1 array is the way to go. As we mentioned, there are different levels of RAID, the four most common being: 0, 1, 0+1 and 5. RAID 0 (or striping) is when data is divided into equal parts (stripe volumes) and each part is stored on a different disk. Performance is improved a great deal when using RAID 0, as you have more than one disk working to read or write data. This level of RAID is mostly used for high-speed data access. RAID 1 (mirroring) and RAID 5 are used when valuable data need to be stored in duplicate. In the case of RAID 1, data is simply copied from one drive to another. Whereas on RAID 5 arrays, mirroring is applied with additional security offered via a drive that also stores parity information. (This can be used to reconstruct missing or lost data). While there are many benefits to using RAID, there are also warning that must be heeded. For instance, if you're using a RAID 0 array and one of your disk fails, you'll lose all your data. In this case then, we recommend backing up your data regularly to an external hard drive or media. If you want more reliability and money is not an issue, opt for a SCSI (pronounced scuzzy) RAID 0 array. This involves buying a RAID 0 SCSI controller and two identical SCSI hard disks. Hardware RAID vs software RAID Before we get down to business, it's worth noting that you can set-up RAID using software (in most cases an operating system such as Windows XP) or if you want a more robust set-up you can go the hardware route and buy a PCI RAID controller. Most motherboard manufacturers such as Asus, Gigabyte and MSI include hardware RAID controllers on their mid and high-end motherboards. Compared to a hardware RAID controller, the software RAID approach is cheaper. However, if you want maximum performance and a wider range of RAID support, a hardware controller is the way forward. This is because hardware controllers have their own dedicated processor and in some instances also feature on-board buffer memory. If you're going the software route, you can skip buying the controller and simply decide on the interface, speed and size of your drives. If you opt for the hardware option, first decide which hard drive interface you plan to use. The three main choices that are currently on the market are IDE, Serial ATA (SATA) and SCSI. If you opt for SCSI, you'll have to invest in both a SCSI RAID controller and SCSI hard disks.However, if you choose the IDE or SATA route, check if your board supports this via its onboard controller. How to set-up RAID For the purpose of this workshop, we will be focusing on a hardware IDE RAID implementation, as this will meet the needs of most readers who probably have an IDE hard drives installed in their rigs. Please note: if you are re-using older hard disks, make sure you back-up all your data first as creating a new RAID array will destroy all the existing partitions and therefore all the data. Before you install your new hard drive(s) and secure them, make sure that they can be connected to the RAID controller, without any cables being stretched. Once you've found the appropriate position you can then secure them into place with screws. For instructions on how to connect your drives correctly to your RAID controller or set a particular RAID type, we suggest keeping your controller's user manual handy. Once you've installed your components, boot up your PC and if your installation is successful you should see a screen that shows your RAID controller searching its various channels for hard drives. Depending on which RAID controller you have, you'll have to press a specific key to enter the controller's BIOS. For instance, Silicon Image's controller uses the F10 key. You'll now enter the RAID BIOS main menu. First navigate to the RAID Mode field and select your desired RAID level. Next, choose your array's block size. This refers to the size of each portion that your data will be broken up into by the RAID controller. We recommend setting the block size to Optimal or Automatic, as performance varies quite drastically based on the sort of data you're dealing with. For example, if the average size of your files is less than a megabyte, setting the block size to 32Kbytes will be counter productive as most hard drives are more than capable of quickly reading and writing this file of this size anyway. Next, under Disk list, highlight the drive(s) you wish you insert into the array and move them into the 'Array Disk' List (see pic A). Once you're finished, hit the done key. At this point, your RAID BIOS might ask you whether or not it can clear the data on the disks. Press Y to continue and your RAID array will be set-up. Next, reboot your PC and enter its operating system or install the OS if your RAID array is the boot partition. It's now time to create a partition on your RAID array. This can be done from Control Panel/ Administrative tools/ Computer Management/ Disk Management. For more information on hard disk partitioning, refer to our 'Split Smart' workshop available on www.itp.net.||**||Windows Hard disk interface advice |~||~||~|IDE (Integrated Drive Electronics) -Cheapest interface currently available -Comes standard on almost all motherboards -Offers least amount of bandwidth (133Mbytes/s) -Mostly used in homes, offices and low-end servers. Verdict: If cash is an issue, an IDE RAID set-up is the cheapest route. Some medium and high-end motherboards even offer IDE RAID controllers as standard. SATA (Serial Advanced Technology Attachment) -Standard on newer motherboards -Costs slightly more than its IDE counterpart -Offers a theoretical bandwidth of 3Gbits/s (latest SATA version),however this can only be achieved via one-to-one connections (i.e. controller to drive). Verdict: If you want more performance but don't have cash to spend on a SCSI set-up, SATA is the way to go. SCSI (Small Computer System Interface) -Mostly used in workstations and server environments -There are a number of different SCSI standards available such as Ultra 80, Ultra 160 and Ultra 320 -Ultra 320 is currently the fastest SCSI standard around -All of these standards allow users to connect up to 45 drives (if the RAID controller offers three distinct SCSI channels). Verdict: If you want the best performance and expandability for your RAID set-up, SCSI is - right now - the leader of the pack. Just make sure you’re prepared to pay for it.||**||Raid in a nutshell|~||~||~|RAID 0 - (Striping) Data is divided into equal parts and each part is stored on a different disk. Minimum no. of drives: 2 RAID 1 - (Mirroring) Data is copied from one drive to another. Minimum no. of drives: 2 RAID 0+1 - Striping and mirroring combined. Minimum no. of drives: 4 RAID 5 - Mirroring is applied with additional security offered via parity data. Minimum no. of drives: 3||**||

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