1 00:00:00,240 --> 00:00:02,040 In this lesson, you're going to learn 2 00:00:02,040 --> 00:00:05,370 how to troubleshoot hardware issues in a Linux system. 3 00:00:05,370 --> 00:00:07,710 Now it can take some time to troubleshoot and solve 4 00:00:07,710 --> 00:00:10,110 hardware-related issues on Linux. 5 00:00:10,110 --> 00:00:12,390 Even highly experienced system administrators 6 00:00:12,390 --> 00:00:13,710 will sometimes spend hours 7 00:00:13,710 --> 00:00:15,420 working to solve some kind of mysterious 8 00:00:15,420 --> 00:00:17,850 hardware or software discrepancy. 9 00:00:17,850 --> 00:00:20,610 So in this lesson, my goal is not to make you 10 00:00:20,610 --> 00:00:23,820 an absolute expert, but instead I want to help you 11 00:00:23,820 --> 00:00:25,920 identify things quicker and easier 12 00:00:25,920 --> 00:00:28,290 when you're troubleshooting hardware in Linux. 13 00:00:28,290 --> 00:00:29,520 You're going to learn what's causing 14 00:00:29,520 --> 00:00:31,230 your Linux hardware to malfunction 15 00:00:31,230 --> 00:00:33,000 so that way you can get it back up and running 16 00:00:33,000 --> 00:00:34,530 much more quickly. 17 00:00:34,530 --> 00:00:36,450 Now many different things can cause problems 18 00:00:36,450 --> 00:00:37,620 with Linux hardware, 19 00:00:37,620 --> 00:00:39,870 but before you start trying to diagnose them, 20 00:00:39,870 --> 00:00:42,510 it's really smart to learn about the most common issues 21 00:00:42,510 --> 00:00:44,670 and where you're most likely to find them. 22 00:00:44,670 --> 00:00:46,800 Now some of the most common hardware issues 23 00:00:46,800 --> 00:00:50,070 are keyboard mapping issues, communication port issues, 24 00:00:50,070 --> 00:00:53,250 printer issues, memory issues, video issues 25 00:00:53,250 --> 00:00:54,870 and storage adapter issues. 26 00:00:54,870 --> 00:00:57,630 So we'll take a look at those throughout this lesson. 27 00:00:57,630 --> 00:01:00,660 First, let's talk about keyboard mapping issues. 28 00:01:00,660 --> 00:01:03,060 Now certain keyboard keys when they're pressed 29 00:01:03,060 --> 00:01:05,580 may produce an unexpected character on the screen 30 00:01:05,580 --> 00:01:07,650 or no character at all. 31 00:01:07,650 --> 00:01:10,140 This is the most common and overt system 32 00:01:10,140 --> 00:01:12,120 of keyboard mapping issues. 33 00:01:12,120 --> 00:01:13,980 The most likely cause of these issues 34 00:01:13,980 --> 00:01:16,530 is that the system has configured the wrong keyboard layout 35 00:01:16,530 --> 00:01:18,510 or the wrong language to use. 36 00:01:18,510 --> 00:01:21,420 To fix this problem, make sure you can correctly identify 37 00:01:21,420 --> 00:01:23,220 the layout of the physical keyboard. 38 00:01:23,220 --> 00:01:25,170 Not just its overall design type, 39 00:01:25,170 --> 00:01:27,840 but its actual specific regional layout. 40 00:01:27,840 --> 00:01:30,570 Once you've identified the physical layout of your keyboard, 41 00:01:30,570 --> 00:01:35,100 use the command localectl and the word status 42 00:01:35,100 --> 00:01:37,620 to verify the layout that the system is using. 43 00:01:37,620 --> 00:01:39,810 If it's not the same as what you expect, 44 00:01:39,810 --> 00:01:41,910 you want to list the available key maps, 45 00:01:41,910 --> 00:01:45,510 identify the correct one and then set it on your system. 46 00:01:45,510 --> 00:01:47,880 If you're accessing a Linux system remotely, 47 00:01:47,880 --> 00:01:50,520 your remote terminal client may have some options 48 00:01:50,520 --> 00:01:53,220 for addressing keyboard mapping issues too. 49 00:01:53,220 --> 00:01:55,680 SSH clients like PuTTY will enable you 50 00:01:55,680 --> 00:01:56,640 to change the effects 51 00:01:56,640 --> 00:01:59,340 that certain keystrokes have on the environment. 52 00:01:59,340 --> 00:02:02,310 For example, you can configure the backspace character 53 00:02:02,310 --> 00:02:03,960 to move one character to the left 54 00:02:03,960 --> 00:02:05,730 without deleting the character. 55 00:02:05,730 --> 00:02:07,710 This can be helpful in certain applications 56 00:02:07,710 --> 00:02:10,919 that don't handle the default behavior particularly well. 57 00:02:10,919 --> 00:02:12,240 Now another thing we want to talk about 58 00:02:12,240 --> 00:02:14,520 is communication ports like USB 59 00:02:14,520 --> 00:02:17,400 because these can fail to recognize an attached device 60 00:02:17,400 --> 00:02:21,240 or that connection to that device may become unreliable. 61 00:02:21,240 --> 00:02:23,310 Your first step should always be to ensure 62 00:02:23,310 --> 00:02:25,860 the device is correctly slotted into the port 63 00:02:25,860 --> 00:02:28,260 by making sure it has a good physical connection 64 00:02:28,260 --> 00:02:31,290 and the physical cables are not loose or damaged. 65 00:02:31,290 --> 00:02:33,600 Also, make sure the power's being supplied 66 00:02:33,600 --> 00:02:35,040 to the bus adapter. 67 00:02:35,040 --> 00:02:37,320 If these two things don't fix your issue, 68 00:02:37,320 --> 00:02:38,250 then you need to ensure 69 00:02:38,250 --> 00:02:39,810 that any necessary drivers 70 00:02:39,810 --> 00:02:42,270 have been installed and loaded into the kernel, 71 00:02:42,270 --> 00:02:44,940 depending on the type of interface you're going to be using. 72 00:02:44,940 --> 00:02:46,290 Now certain devices, 73 00:02:46,290 --> 00:02:48,660 when they're connected to a serial port, for instance, 74 00:02:48,660 --> 00:02:50,220 will request a consult interface 75 00:02:50,220 --> 00:02:52,350 with the Linux operating system. 76 00:02:52,350 --> 00:02:54,420 Linux will then typically assign a port 77 00:02:54,420 --> 00:02:59,420 to that interface at /dev/ttyS and a number 78 00:02:59,640 --> 00:03:01,830 where the number is the number of the console 79 00:03:01,830 --> 00:03:03,150 and these start out at zero 80 00:03:03,150 --> 00:03:05,730 and then increment by one each time. 81 00:03:05,730 --> 00:03:08,070 Another area we need to consider is printers 82 00:03:08,070 --> 00:03:10,170 and they are a common source of issues. 83 00:03:10,170 --> 00:03:13,200 In many cases, the printer itself will be at fault. 84 00:03:13,200 --> 00:03:15,600 For example, your printer may be out of ink 85 00:03:15,600 --> 00:03:16,920 or may be out of paper. 86 00:03:16,920 --> 00:03:18,360 It may have a paper jam. 87 00:03:18,360 --> 00:03:20,130 It may be misaligned or damaged 88 00:03:20,130 --> 00:03:21,840 or have some kind of broken component. 89 00:03:21,840 --> 00:03:23,190 There's lots of different issues 90 00:03:23,190 --> 00:03:25,080 you can experience with a printer. 91 00:03:25,080 --> 00:03:27,060 For these issues, you want to consult 92 00:03:27,060 --> 00:03:30,450 the printer's help manual and the manufacturer's website. 93 00:03:30,450 --> 00:03:31,830 In other cases though, 94 00:03:31,830 --> 00:03:33,690 you may be able to troubleshoot the issues 95 00:03:33,690 --> 00:03:35,880 from your Linux client or server. 96 00:03:35,880 --> 00:03:38,100 As always, ensure your specific printer 97 00:03:38,100 --> 00:03:40,620 is supported by Linux compatible drivers 98 00:03:40,620 --> 00:03:43,890 and that those drivers have been loaded by the kernel. 99 00:03:43,890 --> 00:03:45,870 If you're trying to connect to your printer over a network, 100 00:03:45,870 --> 00:03:48,600 but you can't, it may be a networking issue 101 00:03:48,600 --> 00:03:51,360 so use network diagnostic tools like ping 102 00:03:51,360 --> 00:03:53,820 to ensure your printer is identifiable on the network 103 00:03:53,820 --> 00:03:56,430 and then it can actually be reached over the network. 104 00:03:56,430 --> 00:03:58,200 If your printer becomes sluggish, 105 00:03:58,200 --> 00:04:01,350 use lpq to check the status of its print jobs 106 00:04:01,350 --> 00:04:02,700 and look at the queue. 107 00:04:02,700 --> 00:04:05,970 If any jobs are too large or there's too many in the queue, 108 00:04:05,970 --> 00:04:08,400 you can use lprm as a command 109 00:04:08,400 --> 00:04:11,580 to stop a job with the job number that you provide. 110 00:04:11,580 --> 00:04:13,140 For example, if I want to remove 111 00:04:13,140 --> 00:04:14,760 job four from the print queue, 112 00:04:14,760 --> 00:04:19,760 I can enter lprm4 and hit enter at the command prompt. 113 00:04:19,860 --> 00:04:21,300 This will help clear up the queue 114 00:04:21,300 --> 00:04:23,940 and then lighten the load on that particular printer. 115 00:04:23,940 --> 00:04:25,800 Now from a software perspective, 116 00:04:25,800 --> 00:04:28,290 we can also have issues with memory leaks. 117 00:04:28,290 --> 00:04:29,820 Now memory can actually leak 118 00:04:29,820 --> 00:04:32,610 when a process fails to free up the allocated memory 119 00:04:32,610 --> 00:04:34,140 when it's no longer needed. 120 00:04:34,140 --> 00:04:36,210 The total available memory in your system then 121 00:04:36,210 --> 00:04:39,240 becomes quickly exhausted as these leaks happen. 122 00:04:39,240 --> 00:04:41,730 This can lead to general performance degradation 123 00:04:41,730 --> 00:04:44,730 or system instability because other software 124 00:04:44,730 --> 00:04:47,040 can no longer access memory that it needs 125 00:04:47,040 --> 00:04:49,140 because we've leaked out this memory. 126 00:04:49,140 --> 00:04:51,690 In these cases, you can use memory monitoring tools 127 00:04:51,690 --> 00:04:54,630 like free to identify where those leaks are happening 128 00:04:54,630 --> 00:04:58,230 and identify the process and then go to something like top 129 00:04:58,230 --> 00:05:01,320 to monitor the process and identify the true problem. 130 00:05:01,320 --> 00:05:04,290 Once you've identified that process, you can then kill it, 131 00:05:04,290 --> 00:05:06,540 freeing up that memory for good. 132 00:05:06,540 --> 00:05:07,860 Now Linux also has ways 133 00:05:07,860 --> 00:05:10,290 of detecting faults during operations. 134 00:05:10,290 --> 00:05:12,540 For example, system logs will record 135 00:05:12,540 --> 00:05:14,760 a machine check exception error message 136 00:05:14,760 --> 00:05:16,830 anytime there's an issue with RAM. 137 00:05:16,830 --> 00:05:18,690 Now if you look through your logs, 138 00:05:18,690 --> 00:05:20,640 you might be able to look for these error messages 139 00:05:20,640 --> 00:05:23,370 by using a command like mcelog. 140 00:05:23,370 --> 00:05:25,470 This will retrieve and print these error messages 141 00:05:25,470 --> 00:05:27,090 for easier analysis. 142 00:05:27,090 --> 00:05:29,610 If the messages contain error-correcting codes 143 00:05:29,610 --> 00:05:31,290 or ECC errors, 144 00:05:31,290 --> 00:05:32,880 this is one of the memory modules 145 00:05:32,880 --> 00:05:35,310 that has probably failed and causing these errors 146 00:05:35,310 --> 00:05:37,410 so you're going to be looking at it as a hardware issue 147 00:05:37,410 --> 00:05:40,530 and not a software issue in this particular case. 148 00:05:40,530 --> 00:05:43,260 Now another thing we want to talk about is video errors. 149 00:05:43,260 --> 00:05:45,630 Common video-related issues include things 150 00:05:45,630 --> 00:05:48,240 like consistent or intermittent black screens, 151 00:05:48,240 --> 00:05:49,920 incorrectly display colors, 152 00:05:49,920 --> 00:05:52,080 multiple monitors not being detected, 153 00:05:52,080 --> 00:05:54,810 sluggish performance in video intensive applications 154 00:05:54,810 --> 00:05:56,520 and other things like this. 155 00:05:56,520 --> 00:05:58,620 Now some these issues can be addressed 156 00:05:58,620 --> 00:06:01,290 by ensuring that monitors and other display devices 157 00:06:01,290 --> 00:06:03,300 are properly connected and compatible 158 00:06:03,300 --> 00:06:05,580 with the system and user software. 159 00:06:05,580 --> 00:06:06,720 When it comes to performance 160 00:06:06,720 --> 00:06:08,640 of video intensive applications though, 161 00:06:08,640 --> 00:06:11,850 you want to make sure you have good graphic card support 162 00:06:11,850 --> 00:06:15,960 and that includes a GPU driver inside of the Linux kernel. 163 00:06:15,960 --> 00:06:18,990 This is often one of the biggest hurdles inside of Linux 164 00:06:18,990 --> 00:06:21,390 and so it's crucial to have the latest drivers 165 00:06:21,390 --> 00:06:24,660 that will work to give you optimal video performance. 166 00:06:24,660 --> 00:06:26,970 Now another hardware problem you might come across 167 00:06:26,970 --> 00:06:29,460 is actually a faulty bus adapter. 168 00:06:29,460 --> 00:06:31,350 If you have a faulty bus adapter, 169 00:06:31,350 --> 00:06:33,390 you might see some possible indications 170 00:06:33,390 --> 00:06:35,400 like poor data transfer speeds, 171 00:06:35,400 --> 00:06:37,710 less total space available than expected, 172 00:06:37,710 --> 00:06:39,720 excessive read or write errors, 173 00:06:39,720 --> 00:06:41,730 inability to read or write at all, 174 00:06:41,730 --> 00:06:43,830 the system can't detect devices anymore 175 00:06:43,830 --> 00:06:45,300 and things like that. 176 00:06:45,300 --> 00:06:48,450 Now the problem here might be the physical HBA itself 177 00:06:48,450 --> 00:06:50,100 or host bust adapter. 178 00:06:50,100 --> 00:06:51,810 Or it might be with the interface 179 00:06:51,810 --> 00:06:53,910 that the HBA is actually connecting to 180 00:06:53,910 --> 00:06:56,190 like a SCSI or SATA device. 181 00:06:56,190 --> 00:06:58,920 The first step is to ensure the host bus adapter 182 00:06:58,920 --> 00:07:00,540 is actually powered on. 183 00:07:00,540 --> 00:07:02,940 Then you need to ensure that the storage device 184 00:07:02,940 --> 00:07:04,770 you're connecting to that HBA 185 00:07:04,770 --> 00:07:06,810 is using the appropriate interface. 186 00:07:06,810 --> 00:07:09,210 And of course you want to ensure that all the devices 187 00:07:09,210 --> 00:07:11,700 are properly slotted and cabled together 188 00:07:11,700 --> 00:07:13,890 and making sure that they're all damage free 189 00:07:13,890 --> 00:07:15,930 and working properly. 190 00:07:15,930 --> 00:07:18,690 Another thing we want to talk about is RAID arrays. 191 00:07:18,690 --> 00:07:22,320 Now we've talked before about mdadm as a command 192 00:07:22,320 --> 00:07:25,470 and this is a command that's used to manage our RAID arrays. 193 00:07:25,470 --> 00:07:27,540 If you use the -F option, 194 00:07:27,540 --> 00:07:29,400 this will activate monitor mode 195 00:07:29,400 --> 00:07:31,980 which enables you to identify missing or failed drives 196 00:07:31,980 --> 00:07:33,780 inside that RAID array. 197 00:07:33,780 --> 00:07:35,940 You can then use some of the command's other modes 198 00:07:35,940 --> 00:07:37,080 to rebuild the array 199 00:07:37,080 --> 00:07:38,790 after you've removed the faulty drive 200 00:07:38,790 --> 00:07:40,380 and put a new one in. 201 00:07:40,380 --> 00:07:42,990 Some other useful options for troubleshooting RAID issues 202 00:07:42,990 --> 00:07:45,390 include using the -f 203 00:07:45,390 --> 00:07:48,300 which is used to mark a specified device as faulty 204 00:07:48,300 --> 00:07:50,760 and prepare it for removal from that array. 205 00:07:50,760 --> 00:07:52,860 You can also use the -r option 206 00:07:52,860 --> 00:07:56,160 which is used to remove the specified device from the array. 207 00:07:56,160 --> 00:07:57,960 If you use the keyword failed, 208 00:07:57,960 --> 00:08:00,840 this will specify that all the devices marked as faulty 209 00:08:00,840 --> 00:08:02,340 should be removed. 210 00:08:02,340 --> 00:08:04,380 If you use --re-add, 211 00:08:04,380 --> 00:08:07,110 this is an option that's used to add a removed device 212 00:08:07,110 --> 00:08:10,080 back into the array for the purposes of recovering data 213 00:08:10,080 --> 00:08:11,820 that's stored on that device. 214 00:08:11,820 --> 00:08:13,650 If you use the -a option, 215 00:08:13,650 --> 00:08:15,180 this is going to be used to add a device 216 00:08:15,180 --> 00:08:17,460 to the array as a hot spare. 217 00:08:17,460 --> 00:08:18,990 If the array is degraded, 218 00:08:18,990 --> 00:08:21,750 it's going to rebuild data on that spare for you. 219 00:08:21,750 --> 00:08:23,940 This behavior only applies to devices 220 00:08:23,940 --> 00:08:25,560 that are unable to be re-added 221 00:08:25,560 --> 00:08:28,380 or were never part of the array to begin with. 222 00:08:28,380 --> 00:08:31,710 Another helpful command we have is lshw. 223 00:08:31,710 --> 00:08:35,850 Now the lshw command is basically the list hardware command. 224 00:08:35,850 --> 00:08:38,309 It's going to list out each detected hardware component 225 00:08:38,309 --> 00:08:41,850 on the system and provide details about each device. 226 00:08:41,850 --> 00:08:44,970 This command pulls information from many different files 227 00:08:44,970 --> 00:08:46,590 in many different locations 228 00:08:46,590 --> 00:08:49,530 for those different device files on the system. 229 00:08:49,530 --> 00:08:52,230 For example, it can pull data from /proc 230 00:08:52,230 --> 00:08:54,630 and then output it in a hierarchical format. 231 00:08:54,630 --> 00:08:57,150 The information that lshw outputs 232 00:08:57,150 --> 00:08:59,820 will include things like your vendors, your product names, 233 00:08:59,820 --> 00:09:01,740 your capacity, your speed 234 00:09:01,740 --> 00:09:03,660 and other attributes of the motherboard 235 00:09:03,660 --> 00:09:07,170 including the CPU, RAM modules, peripheral devices, 236 00:09:07,170 --> 00:09:09,630 storage devices and much more. 237 00:09:09,630 --> 00:09:12,450 You can use lshw or list hardware 238 00:09:12,450 --> 00:09:13,980 to identify whether or not a device 239 00:09:13,980 --> 00:09:15,720 is recognized by the kernel 240 00:09:15,720 --> 00:09:16,980 as well as to review a device's 241 00:09:16,980 --> 00:09:19,290 capabilities and characteristics. 242 00:09:19,290 --> 00:09:20,430 To run this command, 243 00:09:20,430 --> 00:09:23,640 type in lshw and then the options you want 244 00:09:23,640 --> 00:09:25,200 at the command prompt. 245 00:09:25,200 --> 00:09:28,440 The output of the lshw is going to group the devices 246 00:09:28,440 --> 00:09:30,630 into one of several classes. 247 00:09:30,630 --> 00:09:32,580 You can then filter the total result 248 00:09:32,580 --> 00:09:35,820 by specifying a class with a -c option. 249 00:09:35,820 --> 00:09:40,820 For example, if I typed in lshw -c and then network, 250 00:09:41,340 --> 00:09:44,580 I'm only going to see details about network class devices 251 00:09:44,580 --> 00:09:48,150 like network interface cards or a wifi adapter. 252 00:09:48,150 --> 00:09:50,940 To see a list of classes currently in use in your system, 253 00:09:50,940 --> 00:09:55,940 you can enter the command lshw -short, pipe sort-k2 254 00:09:57,180 --> 00:09:59,970 and this will generate a non-detail list of devices 255 00:09:59,970 --> 00:10:04,530 sorted based on the second column which is the class column. 256 00:10:04,530 --> 00:10:06,240 The next command we're going to talk about 257 00:10:06,240 --> 00:10:08,880 is the dmidecode command. 258 00:10:08,880 --> 00:10:10,230 Now this command is going to dump 259 00:10:10,230 --> 00:10:13,650 the system's Desktop Management Interface or DMI 260 00:10:13,650 --> 00:10:14,550 and take that table 261 00:10:14,550 --> 00:10:17,190 and present it in a human readable format. 262 00:10:17,190 --> 00:10:19,620 The DMI table is an industry standard 263 00:10:19,620 --> 00:10:22,740 for tracking information about hardware components. 264 00:10:22,740 --> 00:10:26,310 However, the authors of the dmidecode command 265 00:10:26,310 --> 00:10:28,950 caution us that the information in the DMI tables 266 00:10:28,950 --> 00:10:31,050 is more often than not 267 00:10:31,050 --> 00:10:34,500 inaccurate, incomplete or simply wrong. 268 00:10:34,500 --> 00:10:37,410 Therefore, you don't want to rely on the DMI table 269 00:10:37,410 --> 00:10:39,840 as your sole source of hardware information, 270 00:10:39,840 --> 00:10:42,030 but it can be a useful tool 271 00:10:42,030 --> 00:10:44,190 to act as a second or third source 272 00:10:44,190 --> 00:10:45,900 when you're correlating with others. 273 00:10:45,900 --> 00:10:49,170 To run this command, simply type in dmidecode 274 00:10:49,170 --> 00:10:51,480 and the options at the command prompt. 275 00:10:51,480 --> 00:10:52,920 Another tool we can use 276 00:10:52,920 --> 00:10:56,850 is the Automatic Bug Reporting Tool or ABRT. 277 00:10:56,850 --> 00:10:58,860 This is a utility that's typically used 278 00:10:58,860 --> 00:11:01,380 on Fedora and Red Hat-based systems 279 00:11:01,380 --> 00:11:02,700 and it analyzes and reports 280 00:11:02,700 --> 00:11:05,640 on problems detected during system runtime. 281 00:11:05,640 --> 00:11:07,830 ABRT will be used to collect data 282 00:11:07,830 --> 00:11:10,170 like memory dumps from crashed applications 283 00:11:10,170 --> 00:11:11,790 that'll help system administrators 284 00:11:11,790 --> 00:11:13,980 diagnose and troubleshoot issues. 285 00:11:13,980 --> 00:11:16,710 It can also report on problems of various devices 286 00:11:16,710 --> 00:11:20,580 such as MCE's that typically indicate hardware failures. 287 00:11:20,580 --> 00:11:24,480 ABRT will run as the abrtd daemon 288 00:11:24,480 --> 00:11:27,960 and can be configured using abrt-cli 289 00:11:27,960 --> 00:11:29,490 if you're using the command line 290 00:11:29,490 --> 00:11:33,960 or abrt-gui if you're using the graphical user interface, 291 00:11:33,960 --> 00:11:36,720 depending on your system and your own preferences. 292 00:11:36,720 --> 00:11:38,640 Now you can use both of these utilities 293 00:11:38,640 --> 00:11:42,150 to list problem data, view details about that problem data, 294 00:11:42,150 --> 00:11:43,980 analyze and report on that problem data 295 00:11:43,980 --> 00:11:46,560 and remove unnecessary reports. 296 00:11:46,560 --> 00:11:48,600 Remember, when troubleshooting hardware issues, 297 00:11:48,600 --> 00:11:50,520 the first step is to ensure the hardware devices 298 00:11:50,520 --> 00:11:52,770 are supported by robust drivers 299 00:11:52,770 --> 00:11:54,720 Then ensure the necessary drivers 300 00:11:54,720 --> 00:11:57,360 are installed and loaded into your kernel. 301 00:11:57,360 --> 00:11:58,860 Always ensure the hardware devices 302 00:11:58,860 --> 00:12:00,360 are compatible with the Linux software 303 00:12:00,360 --> 00:12:03,660 that controls it, manages it and interfaces with it. 304 00:12:03,660 --> 00:12:06,180 Verify that the system has the correct keyboard layout 305 00:12:06,180 --> 00:12:07,050 and language set 306 00:12:07,050 --> 00:12:09,570 because this will solve a lot of your problems. 307 00:12:09,570 --> 00:12:12,210 Also, when you're working with network-enabled printers, 308 00:12:12,210 --> 00:12:14,850 make sure it's identifiable on your network. 309 00:12:14,850 --> 00:12:16,410 If you're having a problem with the printer, 310 00:12:16,410 --> 00:12:19,170 you can use the lprm command to be able to stop 311 00:12:19,170 --> 00:12:22,320 large or numerous print jobs from that system. 312 00:12:22,320 --> 00:12:23,790 If you have memory issues, 313 00:12:23,790 --> 00:12:25,920 you can check the mcelog 314 00:12:25,920 --> 00:12:28,680 and that way you can see what errors might exist. 315 00:12:28,680 --> 00:12:30,000 Anytime you're trying to figure out 316 00:12:30,000 --> 00:12:32,070 if your RAM modules are bad or not, 317 00:12:32,070 --> 00:12:35,370 you can use the command line utility memtester. 318 00:12:35,370 --> 00:12:38,250 Also, if you're having problems with your graphics card, 319 00:12:38,250 --> 00:12:39,150 you should check to make sure 320 00:12:39,150 --> 00:12:43,020 you have the latest GPU drivers from your vendor's website. 321 00:12:43,020 --> 00:12:45,540 Always ensure that your storage and peripheral devices 322 00:12:45,540 --> 00:12:47,880 are properly slotted into the correct buses 323 00:12:47,880 --> 00:12:50,160 to make sure they're being recognized by your system 324 00:12:50,160 --> 00:12:52,350 and ensure that the cables are connected properly 325 00:12:52,350 --> 00:12:54,480 and that they're not loose or damaged. 326 00:12:54,480 --> 00:12:56,580 If you want to identify connected hardware, 327 00:12:56,580 --> 00:12:59,340 you can always use the lshw command 328 00:12:59,340 --> 00:13:01,620 which means list hardware. 329 00:13:01,620 --> 00:13:04,440 Also, if you're using dmidecode, 330 00:13:04,440 --> 00:13:07,140 remember, it may produce inaccurate results. 331 00:13:07,140 --> 00:13:09,990 We're even told this by the manufacturers of that tool, 332 00:13:09,990 --> 00:13:12,930 but it still does provide some useful information. 333 00:13:12,930 --> 00:13:15,660 Finally, if you have programs that are crashing a lot, 334 00:13:15,660 --> 00:13:17,280 you should always review your crash data 335 00:13:17,280 --> 00:13:19,920 that's compiled by the ABRT utility 336 00:13:19,920 --> 00:13:22,620 inside of your Linux operating system. 337 00:13:22,620 --> 00:13:25,020 All right, I know we just covered a lot of information 338 00:13:25,020 --> 00:13:27,390 so let me provide a little bit of a summary here. 339 00:13:27,390 --> 00:13:29,610 Remember, Linux hardware troubleshooting 340 00:13:29,610 --> 00:13:31,320 requires a good amount of knowledge 341 00:13:31,320 --> 00:13:35,100 and familiarity with the command line and system messages. 342 00:13:35,100 --> 00:13:36,990 You have learned how to use a wide variety 343 00:13:36,990 --> 00:13:39,270 of tools and utilities in this lesson, 344 00:13:39,270 --> 00:13:42,690 but most importantly, you need to work methodically. 345 00:13:42,690 --> 00:13:44,850 As you understand the different types of hardware issues 346 00:13:44,850 --> 00:13:46,530 and how to address those issues, 347 00:13:46,530 --> 00:13:48,420 always have a standardized process 348 00:13:48,420 --> 00:13:50,040 during your troubleshooting. 349 00:13:50,040 --> 00:13:51,000 Once you've done that 350 00:13:51,000 --> 00:13:52,680 and you've learned the Linux utilities, 351 00:13:52,680 --> 00:13:55,470 you can start troubleshooting much more efficiently. 352 00:13:55,470 --> 00:13:57,210 Hopefully, next time you have something 353 00:13:57,210 --> 00:13:58,980 go wrong with one of your pieces of hardware, 354 00:13:58,980 --> 00:14:00,540 it'll be easier for you to fix 355 00:14:00,540 --> 00:14:02,550 now that you know some of the common tools you can use 356 00:14:02,550 --> 00:14:03,510 to do that. 357 00:14:03,510 --> 00:14:06,720 However, never forget that despite your best efforts, 358 00:14:06,720 --> 00:14:08,700 sometimes you'll never be able to figure out 359 00:14:08,700 --> 00:14:10,530 exactly what that problem is 360 00:14:10,530 --> 00:14:11,580 and you may have to replace 361 00:14:11,580 --> 00:14:13,620 parts or components in the system. 362 00:14:13,620 --> 00:14:15,690 Sometimes it can just be bad hardware 363 00:14:15,690 --> 00:14:17,250 and it's as simple as that 364 00:14:17,250 --> 00:14:18,990 so keep that in mind the next time 365 00:14:18,990 --> 00:14:21,440 you're working on troubleshooting a Linux system.