1 00:00:00,520 --> 00:00:02,980 In this lesson, we're going to discuss the use of RAIDS 2 00:00:02,980 --> 00:00:04,900 to ensure your data redundancy. 3 00:00:04,900 --> 00:00:06,060 You first learned about RAIDS 4 00:00:06,060 --> 00:00:08,250 all the way back in your A plus studies. 5 00:00:08,250 --> 00:00:10,440 If you remember a RAID is a redundant array 6 00:00:10,440 --> 00:00:11,920 of independent disks 7 00:00:11,920 --> 00:00:13,170 which is essentially going to allow you 8 00:00:13,170 --> 00:00:15,340 to combine multiple physical hard disks 9 00:00:15,340 --> 00:00:17,580 into a single logical hard disk drive 10 00:00:17,580 --> 00:00:19,650 inside of the operating system. 11 00:00:19,650 --> 00:00:21,530 Now, for the security plus exam 12 00:00:21,530 --> 00:00:23,580 you need to know about a couple of RAID types 13 00:00:23,580 --> 00:00:28,323 including; RAID 0, RAID 1, RAID 5, RAID 6 and RAID 10. 14 00:00:29,240 --> 00:00:32,410 A RAID 0 provides data striping across multiple disks 15 00:00:32,410 --> 00:00:34,490 and is used to increase your performance. 16 00:00:34,490 --> 00:00:36,390 The key word here is striping. 17 00:00:36,390 --> 00:00:38,620 For example, you might use a RAID 0 18 00:00:38,620 --> 00:00:40,610 when you need performance, but you don't care about 19 00:00:40,610 --> 00:00:42,960 fault tolerance, so a good example of this is 20 00:00:42,960 --> 00:00:45,510 I do a lot of video editing and so I really care about 21 00:00:45,510 --> 00:00:48,150 performance there as I'm editing these raw videos 22 00:00:48,150 --> 00:00:50,270 and so by having these two drives working together, 23 00:00:50,270 --> 00:00:51,920 I can do things much quicker 24 00:00:51,920 --> 00:00:53,630 than I could with a single drive. 25 00:00:53,630 --> 00:00:56,620 Now to do a RAID 0, you do need at least two disks 26 00:00:56,620 --> 00:00:58,600 to work in tandem with each other. 27 00:00:58,600 --> 00:01:00,510 The next one we have is a RAID 1 28 00:01:00,510 --> 00:01:02,060 and this is going to provide redundancy 29 00:01:02,060 --> 00:01:05,230 by mirroring the data identically to two hard drives. 30 00:01:05,230 --> 00:01:06,590 So if one drive fails, 31 00:01:06,590 --> 00:01:08,080 the other can continue to operate 32 00:01:08,080 --> 00:01:11,050 because it has a full copy of everything that was on there. 33 00:01:11,050 --> 00:01:13,040 This provides the least amount of downtime 34 00:01:13,040 --> 00:01:15,150 because there is always that complete copy of data 35 00:01:15,150 --> 00:01:17,310 ready at a moment's notice to take over. 36 00:01:17,310 --> 00:01:19,310 This provides wonderful fault tolerance, 37 00:01:19,310 --> 00:01:21,800 but it can it can only be used with two physical hard disks 38 00:01:21,800 --> 00:01:24,910 and that provide you with one single logical hard disk 39 00:01:24,910 --> 00:01:26,690 inside the operating system. 40 00:01:26,690 --> 00:01:28,490 A good example of this is once I'm finished 41 00:01:28,490 --> 00:01:29,750 editing all my videos 42 00:01:29,750 --> 00:01:31,040 and I have the final the final product, 43 00:01:31,040 --> 00:01:32,510 I want to make sure I don't lose it, 44 00:01:32,510 --> 00:01:35,060 so I can actually move that over to a RAID 1 45 00:01:35,060 --> 00:01:37,130 where I get two identical copies of that file 46 00:01:37,130 --> 00:01:39,220 one on each of those drives. 47 00:01:39,220 --> 00:01:41,950 Now, the next one we're going to talk about is a RAID 5. 48 00:01:41,950 --> 00:01:45,150 A RAID 5 is known as a striping disk with parity. 49 00:01:45,150 --> 00:01:48,494 It requires at least three physical disk drives to work, 50 00:01:48,494 --> 00:01:49,327 and it provides fault tolerance 51 00:01:49,327 --> 00:01:51,550 by striping the data across multiple disks 52 00:01:51,550 --> 00:01:54,420 and writing parity data to the multiple disks too. 53 00:01:54,420 --> 00:01:57,530 If one disk fails, the other two can reconstruct the data 54 00:01:57,530 --> 00:02:00,400 based on the parity and they continue to operate. 55 00:02:00,400 --> 00:02:02,040 This means that if one of those drives fails, 56 00:02:02,040 --> 00:02:03,150 I can pull it out, 57 00:02:03,150 --> 00:02:04,260 put in a new drive 58 00:02:04,260 --> 00:02:06,570 and it will rebuild itself inside the RAID 59 00:02:06,570 --> 00:02:09,130 as it keeps moving and operating for the rest of the system. 60 00:02:09,130 --> 00:02:10,650 Next, we have a RAID 6 61 00:02:10,650 --> 00:02:13,810 and a RAID 6 is a modified form of a RAID 5. 62 00:02:13,810 --> 00:02:15,860 In fact, it's one better than a RAID 5 63 00:02:15,860 --> 00:02:17,810 that's why we call it a RAID 6. 64 00:02:17,810 --> 00:02:20,870 Now, it's going to use data striping across multiple disks 65 00:02:20,870 --> 00:02:22,350 just like a RAID 5 did, 66 00:02:22,350 --> 00:02:24,810 but instead of having one stripe for parity data, 67 00:02:24,810 --> 00:02:27,770 it's actually going to have two stripes for parity data. 68 00:02:27,770 --> 00:02:30,030 This requires another disk in the array to work 69 00:02:30,030 --> 00:02:32,280 so you need at least four physical disks, 70 00:02:32,280 --> 00:02:34,930 but that does provide you additional fault tolerance 71 00:02:34,930 --> 00:02:37,220 because you can lose up to two of these four disks 72 00:02:37,220 --> 00:02:39,850 and the RAID will still continue to function. 73 00:02:39,850 --> 00:02:42,920 The last RAID we have is known as a RAID 1 0 74 00:02:42,920 --> 00:02:45,110 which is written as RAID 10. 75 00:02:45,110 --> 00:02:48,260 This combines the advantages of a RAID 1 and a RAID 0 76 00:02:48,260 --> 00:02:51,400 because one plus zero equals 10. 77 00:02:51,400 --> 00:02:54,480 This requires four physical disks just like a RAID 6 78 00:02:54,480 --> 00:02:56,340 and it's going to provide you with a redundant mirror 79 00:02:56,340 --> 00:02:59,140 of striped drives and its fully fault tolerant. 80 00:02:59,140 --> 00:03:01,260 This gives us all the speed of a RAID 0 81 00:03:01,260 --> 00:03:03,920 by splitting up the load across two sets of RAIDs, 82 00:03:03,920 --> 00:03:06,670 but it also gives us the full redundancy of a RAID 1 83 00:03:06,670 --> 00:03:09,030 by having those two RAID 1 in there. 84 00:03:09,030 --> 00:03:12,000 Now, this all works as one combined logical drive 85 00:03:12,000 --> 00:03:13,980 even though it uses those four drives 86 00:03:13,980 --> 00:03:16,100 split up into two pairs of two. 87 00:03:16,100 --> 00:03:19,270 So, when we think of RAIDs, they can be categorized as; 88 00:03:19,270 --> 00:03:22,600 failure resistant, fault-tolerant and disaster-tolerant. 89 00:03:22,600 --> 00:03:24,830 These are our three categories for RAIDs. 90 00:03:24,830 --> 00:03:26,700 Now, if you have a failure-resistant RAID, 91 00:03:26,700 --> 00:03:29,530 that's going to be something like a RAID 1 or a RAID 5 because 92 00:03:29,530 --> 00:03:31,880 it's going to protect against the loss of the array's data 93 00:03:31,880 --> 00:03:34,210 if a single disk fails inside of it. 94 00:03:34,210 --> 00:03:36,260 Now, we talk about fault-tolerant disk systems, 95 00:03:36,260 --> 00:03:38,750 this will be something like a RAID 1 or a RAID 5 again, 96 00:03:38,750 --> 00:03:42,360 or even RAID 6, because even if a single component fails 97 00:03:42,360 --> 00:03:45,200 one of those drives or even one of the cards inside of it, 98 00:03:45,200 --> 00:03:48,220 then that RAID can continue to function properly. 99 00:03:48,220 --> 00:03:50,960 Now, our final category is known as disaster-tolerant, 100 00:03:50,960 --> 00:03:53,240 and so if we call a RAID disaster-tolerant, 101 00:03:53,240 --> 00:03:55,540 this means that the RAIDs has two independent zones 102 00:03:55,540 --> 00:03:58,200 with full access to the data at all times. 103 00:03:58,200 --> 00:04:01,640 A RAID 10 is a good example of a disaster-tolerant RAID, 104 00:04:01,640 --> 00:04:03,800 but so is a RAID 01. 105 00:04:03,800 --> 00:04:05,750 A RAID 01? What's that? 106 00:04:05,750 --> 00:04:07,890 Well, if I create this RAID 01, 107 00:04:07,890 --> 00:04:09,290 I'm going to have a striped array 108 00:04:09,290 --> 00:04:12,640 made up of two mirrored RAID 1, and by doing this, 109 00:04:12,640 --> 00:04:14,410 I could lose either half of the array 110 00:04:14,410 --> 00:04:17,210 and one of those RAID 1 are going to still function, 111 00:04:17,210 --> 00:04:19,520 and that means the system is still going to keep functioning 112 00:04:19,520 --> 00:04:21,250 and is going to make it disaster-tolerant 113 00:04:21,250 --> 00:04:23,010 because I have a full copy of that data 114 00:04:23,010 --> 00:04:25,170 ready to go at all times. 115 00:04:25,170 --> 00:04:27,110 Now RAIDs are a great thing to use 116 00:04:27,110 --> 00:04:29,080 when you're trying to ensure you good redundancy 117 00:04:29,080 --> 00:04:32,570 of your data, online and available at all times. 118 00:04:32,570 --> 00:04:34,460 This helps increase our availability portion 119 00:04:34,460 --> 00:04:37,450 of the CIA triad, and it helps us when we're designing 120 00:04:37,450 --> 00:04:39,808 a high availability system. 121 00:04:39,808 --> 00:04:42,115 (soft music)