RAID 5 & 6
Hello everyone today we're going to talk about RAID 5 and RAID 6. Now previously But I never covered RAID 6. But to understand RAID 6 you need to understand RAID 5 so that's what we're going to talk about. Now RAID stands for redundant array of independent or inexpensive disks. In a RAID setup the data is copied or spread on multiple disks, so that in the event of a disk failure No data would be lost because that data is spread on other disks. So let's talk about RAID 5. Now in order to use RAID 5 you need to have 3 or more disks RAID 5 is a common setup that is used especially in companies and that's because it's fast and it can store a large amount of data. Now in a RAID 5 setup that data is not duplicated but it's striped or spread across multiple disks and in addition to the data There is another very important piece of information that is being evenly spread across all the disks and that information is called parity and Parity is used to rebuild the data in the event of a disk failure now in a RAID 5 setup If 1 disk were to fail you would not lose any data Because RAID 5 is designed to handle a single disk failure So all you would have to do is replace the failed disk with a new one and then RAID 5 would use the parity information from the other disks to rebuild the data on the new hard drive However, if 2 discs were to fail at the same time in a RAID 5 setup, then all the data would be lost because RAID 5 is not designed to handle 2 disk failures at the same time. It can only handle 1 disk failure at a time So in our example here this setup is using 3 disks but since it's using RAID 5, the equivalent size of 2 of these disks are actually used to store data and this is because it takes the equivalent of 1 entire disk to store parity So if these disks were 1 terabyte each, 3 of them combined would equal 3 terabytes but only 2 terabytes would be used for actual storage because 1 terabyte would be used to store parity. And that brings us to RAID 6. Now in order to use RAID 6 you need to have 4 or more disks. Now RAID 6 is just like RAID 5, where the data is striped across all the disks and parity is also spread on all the disks but the difference is in RAID 6, parity is spread twice on all the disks and the reason for this double parity is so that it can handle 2 disks failure at the same time So in a RAID 6 if 2 disks were to fail at the same time, which is pretty rare, no data would be lost And all you would have to do is replace the failed disks and then RAID 6 would use the double parity from the other disks to rebuild the data on the new drives So in our example here RAID 6 is using 4 drives So that would mean that the equivalent of 2 of these drives would be used for actual data storage and the equivalent of 2 disks would be used to store the double parity So again if these disks were 1 terabyte each, that would be equal to 4 terabytes but only 2 terabytes would be used to store data and the other 2 terabytes would be used to store the double parity and it's also important to note that the read performance from RAID 5 and RAID 6 are about the same but as far as writing data This is where RAID 6 suffers greatly because since RAID 6 has to write 2 Independent parity blocks instead of 1, the write performance will be a lot slower when compared to RAID 5 So that's the difference between RAID 5 and RAID 6.
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