1 00:00:00,320 --> 00:00:02,570 To ensure our systems remain online, 2 00:00:02,570 --> 00:00:05,270 we need to ensure that they have redundant power. 3 00:00:05,270 --> 00:00:06,610 Now, there are a lot of different ways 4 00:00:06,610 --> 00:00:08,280 to do this, but let's begin with 5 00:00:08,280 --> 00:00:10,640 the idea of a redundant power supply. 6 00:00:10,640 --> 00:00:12,940 A redundant power supply is simply an enclosure 7 00:00:12,940 --> 00:00:15,420 that provides two or more complete power supplies 8 00:00:15,420 --> 00:00:16,560 inside of one. 9 00:00:16,560 --> 00:00:19,000 You learned about this back in your A plus studies. 10 00:00:19,000 --> 00:00:20,850 Now, most servers are going to utilize 11 00:00:20,850 --> 00:00:23,630 two individual power supplies in the servers case 12 00:00:23,630 --> 00:00:25,400 to ensure that power is always available 13 00:00:25,400 --> 00:00:27,580 to that server at all times. 14 00:00:27,580 --> 00:00:29,520 This eliminates a single point of failure 15 00:00:29,520 --> 00:00:32,250 that really does exist inside your desktop computer. 16 00:00:32,250 --> 00:00:33,540 If you look in your desktop computer, 17 00:00:33,540 --> 00:00:35,660 you only have a single power supply. 18 00:00:35,660 --> 00:00:37,410 If it fails, the entire computer 19 00:00:37,410 --> 00:00:38,660 is going to fail with it. 20 00:00:38,660 --> 00:00:40,900 But, with servers, we have two power supplies, 21 00:00:40,900 --> 00:00:42,380 those redundant power supplies. 22 00:00:42,380 --> 00:00:43,560 And, so, this is going to ensure 23 00:00:43,560 --> 00:00:44,890 that we can mitigate the threat 24 00:00:44,890 --> 00:00:46,580 of power supplies failing on us 25 00:00:46,580 --> 00:00:49,270 and taking down the entire server or system. 26 00:00:49,270 --> 00:00:52,080 Now, speaking of power, for the security plus exam, 27 00:00:52,080 --> 00:00:54,290 you need to know a few conditions that describe 28 00:00:54,290 --> 00:00:55,790 the various issues that can be involved 29 00:00:55,790 --> 00:00:57,030 with a power source. 30 00:00:57,030 --> 00:00:58,790 These include things like surges, 31 00:00:58,790 --> 00:01:02,080 spikes, sags, brownouts, and blackouts. 32 00:01:02,080 --> 00:01:04,450 Again, you learned all of these back in A plus, 33 00:01:04,450 --> 00:01:06,550 so we're just going to do a quick review here. 34 00:01:06,550 --> 00:01:08,330 First, let's cover a surge. 35 00:01:08,330 --> 00:01:09,990 A surge in electrical means that there is 36 00:01:09,990 --> 00:01:11,570 an unexpected increase in the amount 37 00:01:11,570 --> 00:01:13,140 of voltage that's being provided. 38 00:01:13,140 --> 00:01:14,610 So here in the United States, 39 00:01:14,610 --> 00:01:17,120 our power supply is 120 volts. 40 00:01:17,120 --> 00:01:20,630 If that went up to, say, 124 or 125 volts, 41 00:01:20,630 --> 00:01:22,870 that's only a little bit of an increase in power. 42 00:01:22,870 --> 00:01:24,680 So that would be considered a surge. 43 00:01:24,680 --> 00:01:26,350 Now, if it jumped up a lot, 44 00:01:26,350 --> 00:01:28,550 then we would have what we call a spike. 45 00:01:28,550 --> 00:01:31,660 Now, a spike is going to be a short transient voltage 46 00:01:31,660 --> 00:01:33,370 that's going to be due to a short circuit, 47 00:01:33,370 --> 00:01:35,410 a tripped circuit breaker, a power outage, 48 00:01:35,410 --> 00:01:37,150 or even a lightning strike. 49 00:01:37,150 --> 00:01:39,380 This might jump from 120 volt up to 50 00:01:39,380 --> 00:01:42,360 maybe 140 or 150, or even more. 51 00:01:42,360 --> 00:01:45,030 Now, to protect against a surge or a spike, 52 00:01:45,030 --> 00:01:46,970 you should use a surge protector. 53 00:01:46,970 --> 00:01:48,170 A surge protector is going to help you 54 00:01:48,170 --> 00:01:50,090 against those little surges, but if you have 55 00:01:50,090 --> 00:01:52,230 a really good surge protector, it can help 56 00:01:52,230 --> 00:01:54,620 when you have those large spikes as well. 57 00:01:54,620 --> 00:01:56,990 Now, the next thing we're going to talk about is a sag. 58 00:01:56,990 --> 00:01:59,770 A sag is kind of like a surge, but in reverse. 59 00:01:59,770 --> 00:02:02,940 Where a surge went up, a sag is an unexpected decrease 60 00:02:02,940 --> 00:02:04,080 in the amount of voltage provided. 61 00:02:04,080 --> 00:02:05,540 So it's going to go down. 62 00:02:05,540 --> 00:02:07,320 Typically, sags are only for a short duration 63 00:02:07,320 --> 00:02:09,440 of time, and usually it's not even going to 64 00:02:09,440 --> 00:02:11,540 make the power get lost to your computers. 65 00:02:11,540 --> 00:02:14,090 However, when that voltage reduces for longer 66 00:02:14,090 --> 00:02:16,780 than that, it becomes known as a brownout. 67 00:02:16,780 --> 00:02:18,460 A brownout is when a voltage drops 68 00:02:18,460 --> 00:02:20,390 to such an extent, that usually your lights 69 00:02:20,390 --> 00:02:22,980 start dimming and your computer would even shut off. 70 00:02:22,980 --> 00:02:24,930 So, if I'm used to 120 volts, 71 00:02:24,930 --> 00:02:26,060 maybe I'm going to have a brownout where 72 00:02:26,060 --> 00:02:29,070 I drop down to 90, or 80, or 70 volts, 73 00:02:29,070 --> 00:02:30,390 and that's not enough power to keep 74 00:02:30,390 --> 00:02:32,960 the computer running, and so we're going to lose power. 75 00:02:32,960 --> 00:02:34,730 Finally, we have a blackout. 76 00:02:34,730 --> 00:02:36,020 Now, a blackout occurs when there is 77 00:02:36,020 --> 00:02:39,030 a total loss of power for a long period of time. 78 00:02:39,030 --> 00:02:40,360 So, if you're sitting in your house 79 00:02:40,360 --> 00:02:42,610 and the lights all go out and the computers turn off 80 00:02:42,610 --> 00:02:45,160 and it happens for 30 seconds or a minute, 81 00:02:45,160 --> 00:02:47,310 that's considered a prolong amount of time 82 00:02:47,310 --> 00:02:48,540 for a blackout. 83 00:02:48,540 --> 00:02:50,670 Now, another problem associated with these blackouts, 84 00:02:50,670 --> 00:02:53,470 is often when they come back from those blackout conditions, 85 00:02:53,470 --> 00:02:55,490 you get a spike in power that occurs, 86 00:02:55,490 --> 00:02:57,480 and this can damage your computers as well. 87 00:02:57,480 --> 00:02:59,590 Again, this is why those surge protectors 88 00:02:59,590 --> 00:03:01,010 are really important. 89 00:03:01,010 --> 00:03:02,860 In the next lesson, we're going to discuss how 90 00:03:02,860 --> 00:03:04,450 we can protect ourselves form all 91 00:03:04,450 --> 00:03:06,670 of these conditions using proper backup power 92 00:03:06,670 --> 00:03:07,823 and line conditioning.