Storage is a very important part of fault tolerance. If something were to happen to a company's data such as a disk failure that results in data loss, than that could have a serious impact on how the company performs. That's why we need to make sure that if a disk does fail, that no data loss would occur. And one of the best ways to prevent data loss is RAID, RAID stands for redundant array of independent disks. In a RAID setup, the data is copied on multiple disks so that in the event of a disk failure, no data would be lost. Now there are four common types of RAID. There is RAID 0, RAID 1, RAID 5 and RAID 10 Now RAID 0 is not fault tolerant, in fact RAID 0 shouldn't even be called RAID because not only does it not provide fault-tolerance, it actually increases the chance for data loss. Because in a RAID 0, the data is not duplicated but it's actually spread or striped across two separate disks. So it's just one of these disks fails, or if you decide to destroy yourself with a hammer, then all the data will be lost. So the only reason why you would want to use RAID 0 his speed. Because when you have 2 disk controllers working instead of 1, then accessing data is much faster. Now RAID 1 is fault tolerant. In a RAID 1 set up the data is copied on more than one disk, so disk 2 will have the exact same copy of the data as disk 1 So in the event of a single disk failure, such as getting destroyed by a laser beam, then no data loss would happen because the other disk would have a duplicate copy. Next we'll talk about RAID 5 In order to use RAID 5 you need to have 3 or more disks, RAID 5 is probably the most common setup that is used because it's fast and it can store a large amount of data. So in a raid 5 setup, data is not duplicated, but its striped or spread across multiple discs. And in addition to the data, there is another very important piece of information that is being evenly spread across all the disks, and this information is called parity, and parity is used to rebuild the data in the event of a disk failure. But there is a downside to RAID 5, because since the equivalent of an entire disk is used to store parity, it reduces the collective amount of data that can be stored in this array. So for example if all 4 of these disks were 1 terabyte each, that totals 4 terabytes, but in a RAID 5 set up, the total amount that will be used for data storage would be 3 terabytes, because the equivalent of 1 entire disk would be used to store parity. And finally there is raid 10 and RAID 10 is basically what the name says, its combining RAID 1 and RAID 0 together, and you need to use a minimum of 4 disks. So in a RAID 10 set up, a set of 2 disks are mirrored using a RAID 1 set up. Then both sets of the two disks are striped using RAID 0. So RAID 10 benefits from the fault tolerance of RAID 1 and the speed of RAID 0. But the downside in a RAID 10, is that you can only use 50% of the capacity for data storage. So if you are using four discs in a RAID 10 setup, you can only use two of them for actual storage.
what is the BIOS CMOS and UEFI so that's what we're going to talk about in this video now BIOS stands for basic input/output system the BIOS is firmware that's built into the motherboard that initializes the computer's hardware as the computer is being booted and then after it initializes the hardware it then searches for a boot device such as an optical drive or a storage drive to boot software such as an operating system so from the start when you first turn on the computer the computer does what's called a power-on self-test or post which is run by the bios it tests the computer to make sure all the requirements are met and if the hardware is working correctly before starting the operating system if the computer passes the test the internal speaker will make a short single beep which indicates that the computer has passed the test and is booting up normally however if there are no beeps or multiple beeps then that means that the computer has failed the test and s...
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