RAID HOW TO STEP BY STEP GUIDE AND PERFORMANCE COMPARISON
Posted:2007-07-18 By Raid system Number of View:71175
RAID HOW TO STEP BY STEP GUIDE AND PERFORMANCE COMPARISON By :Raid system Posted:2007-07-18 xtreview is your : Video card - cpu - memory - Hard drive - power supply unit source Today we will talk about the Redundant Array Independent Disks, or just RAID. This technology allow to store data using several hard disks by optimizing their work in order to obtain, according to the user need , more safety and reliability, or more performances. There are many RAID versions , and you have already heard about RAID 0, 1, 5 or 10. These figures indicate specific operating modes of RAID technology : we decided to present only the most used. Another point will be checked in this review is the possibility to use RAID technology in a software way     RAID Versions RAID 0 This process, known under the name stripping, for this RAID configuration you have to use at least 2 hard disk working in parallel. The principle is as follows: two (or more) hard disks assembled in RAID 0 appear in a shape single disc . But actually, when you write a file (2 MB for example ) on this array , the file is stripped in a certain number of pieces whose size depends on the number of hard disk. Example: if you have 4 hard disks in RAID 0, all has 128 KB stripping blocks, then the 2 MB file will be splited in 16 distinct file: the first section of the 128 KB data will be written on the disc number 1, the second part on disc 2, the third part on disc 3  .... and so on until u have written the whole file. RAID 0 operation : various file parts are distributed over hard disks The advantage of this method is the multiplication of sources for reading or writing file: where only one hard disk must read or write the whole file, the units assembled in RAID 0 have only one part equal to the size of file divided by the number of discs in the RAID array. Consequently, the more hard disks increase , the larger transfer speed you will get . If the interest of in such configuration is clean, than disadvantage are sensitive , if files are distributed over several discs, then the failure of one (and only one is enough) makes the file completely inaccessible, because it would miss one or more of its part . The loss of one hard disks (bad disk or just failure) in the RAID array result to an overall data loss . For this reason RAID 0 is not used more by experts, because its operation contains too important risk . Statistically, it is twice more probable to lose its files with two hard disks, three times more with three units, etc However, this mode is perfect to work with noncritical data such as games or video , the performance profit could reach 300% with four hard disks. Note that this type of process requires the use of smiliar volume hard disks .To archive the maximun volume . For example if you use 2 hard disk 1 x 40 Gb and 1 x 80 GB the hole raid array volume will be equal to 80 GB . But if u use 2 x 80 GB hard disk the hole volume will be 160 GB . RAID 1 Contrary to RAID 0, RAID 1 does not aim to improve the performances, but at ensuring the data safety . Here we have the option discs mirroring , one disk being the exact copy of the other. In your computer, you see here also only one unit, whose size will be equal to the smallest hard disk . The control of data copying between the two disc is automtaic and you do not have to be occupied by this maintenance. It is completely possible to work with more than two hard disks. In other words you wll have the exact copy of your data in your two disk . So if u use 2 hard disk with 80 GB , the hole accessible read write volume will be only 80 Gb . (80GB data , 80 GB for mirror data ) Finally side performances, it is true that RAID 1 improve this last, it allow to accelerate ( data reading ) since it can read data directly from the 2 discs in parallel (if the controller allows it). RAID 5 This is the combination of the two preceding version: RAID 5 at the same time allow to improve the performances while ensuring a comfortable data safety . Its principle: the use of three hard disks at least, which are put in RAID 0 two by two, while the third is used to store a control block . This system thus allows to recreate the missing data , starting from the two other discs if one disc fail for example RAID 10 (or 1+0) It is operation its slightly different from RAID 5, which requires less CPU resources and which also combines RAID 0 and 1. Here, only one volume will be seen by your computer , but it will be in fact made by up two two discs in RAID 1 (either four units as a whole and at least). The safety is ensured by RAID 1 , the performances by RAID 0 which binds the two groups. . The only disadvantage, is the cost of such unit, since it is necessary to have at least 4 hard disks with the same size. RAID 0+1 It is a RAID 10 version : its not made by two (or more) discs in RAID 1 which are connected in RAID 0 , but with two (or more) RAID 0 units connected between them in a RAID 1. The advantage of this method is to obtain a fast mirroring. This configuration claims for a minimum of 4 hard disks. With 4x 80 GB discs , you will have 160 GB disk space, 160 GB is for mirror. The JBOD The JBOD (Just Bunch of Disks ) is a configuration rather simple to understand : it allow to bind all its hard disks in only one and even unit, without performances profit nor safety. The data are recorded disc by disc in a completely transparent way for user. Thus once the first disc is filled, the remaining data are recorded on the second disc and so on according to the number of discs. The capacity of JBOD volume obtained is simply the sum of your hard disks volume . What is the interest of such RAID , compared to RAID 0 for example? First and contrary to RAID 0, the physical damage of a hard disk does not lead to data loss contained on the other disks. Second, the presence of a great number of discs in a case can cause some probleme : 8 hard disks in Work station are more .... is not alwais easy to use! To transform them in only one units is alwais a good idea � Software or hardware RAID ? The qeustion here , which is best the solution, most powerful? Software or hardware? Let us talk here about the avantage and the dessavantage of each one . Hardware RAID Generally we deal here with a hardware commponent placed usually in PCI or PCI-e slot .This controller deponding on model have sometimes connector with the IDE, Serial ATA or SCSI format. This raid controller in general is equipped with a specific processor, memory, and is able to manage all RAID system version ( thanks to the build in firmware ). From the operating system side the hardware RAID controller . offers a complete virtualisation of the storage system . The operating system see each RAID volume as a disc and is not informed of its physical components. The advantages of this type are : autonomous RAID arrays rebuilding in case of hardware change (Motherboard change for example) ; Hot swap of a hard disk connected to the controller; Maintenance actions and diagnostic are made with dedicated chips, which reduces the processor and system bus role . Here is certain disadvantages: the arrays RAID installed on a hardware controller are very dependant on its structure and even in its firmware, which can causes problems in case of controller failure (user have to buy the same model with the same firmware) the price of this hardware type , this is a worthy controller (equipped with a processor and powerful memory modules ) witch is rather expensive, The Semi-hardware RAID This is the case of the large majority of RAID controllers used, i.e. those which are integrated in the mother charts. They support in general RAID 0 and 1 on IDE or Serial-ATA hard disks . These components are rather cheap . Software RAID The RAID control is provided by a software contained in the operating system. It is rather flexible solution, but which will require a certain effort at the resources levels to function correctly . The advantages of software solution are Clear: flexibility in use and administration; great interworking: you can pass from a machine to another without problem, the only condition is preserving the software , .� the same operating system; it is a free solution. However, some problems are also present: The detection and diagnosis of corrupted array element are absolutely not as powerful as in dedicated hardware controller; Resources used by this method , in particular for RAID 1 or 5 (RAID 0 is not on the contrary light); The reduced raid possibilities with an operating system : Windows XP support officially RAID 0 , Windows 2003 Server support RAID 0, 1 or 5. Mac OS X support RAID 0 and 1, Palm (Linux distributions ) using 2.6 or newer cores support the modes 0, 1, 5, 6 and 10 being implemented. How to repair a raid array? All depond on the raid system used ? For RAID 0 array , all your data are lost! For other configurations, this will depends on your assembly. If you created the RAID array via a hardware solution, the simple replacement of the failing hard disk is enough to restore the array, the controller have the capability to rebuild it. For a software solution, it will be necessary to find the disc in question, to change it and to recreate the array, which requires more investment. The RAID with BIOS The choice of hard disks accessible to RAID array is done here. F10 Key is the most used in the raid setup utlity in our case (Media Shiled Utility) .After having the RAID activated (check the picture above) then save and exit, you should see a message about the raid configuration (a combination of key, or F10 in our case ) . Now you have to choose the type of desired RAID: 0,1, and even 5. Note : Disks Must be empty for any raid setup or u will loose or data . For our used motherboard , it propose the choice between RAID 0 (stripping), 1 (mirroring) or 5. We test here stripping, RAID 0, by choosing two disks hard . Press F7 all data will be will be lost. Click Yes to confirm The selection of discs to used introduced in RAID 0 array is particularly simple The array RAID is now created, and you can see its detail on these screens. ] RAID with Windows Since Windows 2000, the Pro version the operating system Microsoft (Windows Server 2003, NT4, 2000 and XP Pro) are able to support RAID 0,1 or 5, even if Microsoft officially implemented only RAID 0 and 1. It is however possible to make RAID 5 with Windows XP If this mode remains a very dangerous configuration for your data (a failure of one disk will result to a loss of all stored data on the discs array RAID 0), certain users use about it specific cases: video, photo assembly or gaming , There is as many situation where RAID 0 will be able to offer a consequent contribution in term of performances. I peersonally use RAID 0 in my system (using 4* 320 GB HDD) the performance is pretty amazing vs just single drive . For example file move (700 MB) will take under 5 Second , while using only one hard disk this task can take from 15-30 to 60 second depond on the model used. Windows RAID Installation A minimum of two hard disks  with the same size are necessary, in addition to the one where your operating system is installed . Once your hard disks are connected, Go to the computer management ( in the Control panel , then administration Tools . There, choose computer Management , then in the tab Storage, click on discs Management ). As start click with right mouse button on the rectangle presenting the first hard disk which will appear as RAID array in the future . You must remove all the partitions from the to two discs, which requires the greatest precaution, you can by mistake delate other parttition from other hard disks (witch contain your data ). So please check twice . Once this done , click the right button click Create New volume. The manager of disc will allow you to create your array RAID 0. A window opens then, enabling you to select the discs to be included in the array. Here willl appears only the not partiononted discs Select the hard disks which will belong to your RAID 0 array. Click next to arrive at the ultimate stage where you will create your RAID 0 array . Ultimate stage: the creation of the RAID 0 unit; once finished , the RAID array appears in the list of partition and disks. Note finally this software solution is essentially very flexible, this is why you can easily dismount a RAID array , or use external disks hard. What about the RAID performances? For us today we desided to tests the performances of RAID 0 under Windows Vista� The performances RAID 0 unit is equal to the sum of components performances �l The creation of a array RAID 0 vis pennies is very easy to make, while avoiding passing by the BIOS. However, if this solution is flexible , it remains expensive at the same in resources when you use RAID 1 or 5. And once again, do not forget that RAID 0 is not to use without a minimum of precautions! Conclusion Remeber to alwais keep your inprotant data in back up , particularly if you use a RAID 0 array . A privilege solution to save your data from disappearing would be for example a RAID 5 or 10 . xtreview is your : Video card - cpu - memory - Hard drive - power supply unit source we would be happy to answer for your question . if you have suggestion or comment regarding this review our support would be glad to help just join our forum and ask u will get the best answer to discuss check our forum section :-) RATE THIS REVIEW 1 2 3 4 5    / 5   View Stat

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