1 00:00:00,360 --> 00:00:02,220 In this lesson, we're going to discuss 2 00:00:02,220 --> 00:00:04,170 how you can troubleshoot storage issues 3 00:00:04,170 --> 00:00:06,150 using common storage tools available 4 00:00:06,150 --> 00:00:08,340 in the Linux environment to solve these issues 5 00:00:08,340 --> 00:00:09,750 you may come across. 6 00:00:09,750 --> 00:00:12,390 Now organizations of all size and industries 7 00:00:12,390 --> 00:00:14,370 face data storage challenges. 8 00:00:14,370 --> 00:00:16,890 And as an administrator, you're going to face a variety 9 00:00:16,890 --> 00:00:19,500 of issues with local storage devices. 10 00:00:19,500 --> 00:00:21,450 A key aspect of server management 11 00:00:21,450 --> 00:00:24,060 includes ensuring that storage devices are being recognized 12 00:00:24,060 --> 00:00:27,030 by the system, and that they're available to your users. 13 00:00:27,030 --> 00:00:29,160 There are a lot of local storage issues 14 00:00:29,160 --> 00:00:31,860 including missing devices, missing volumes, 15 00:00:31,860 --> 00:00:35,520 missing mount points, degraded storage, performance issues, 16 00:00:35,520 --> 00:00:39,540 resource exhaustion, storage integrity, and many more. 17 00:00:39,540 --> 00:00:41,760 You're going to need to investigate, diagnose, 18 00:00:41,760 --> 00:00:43,050 and suggest solutions 19 00:00:43,050 --> 00:00:45,510 that can affect your storage solutions. 20 00:00:45,510 --> 00:00:47,430 If you want to limit the system resources 21 00:00:47,430 --> 00:00:49,590 for a user in a Linux based server 22 00:00:49,590 --> 00:00:52,440 then you're going to need to use the ulimit command. 23 00:00:52,440 --> 00:00:54,840 Now ulimit is going to be able to set a limit 24 00:00:54,840 --> 00:00:57,660 for the maximum number of open file descriptors. 25 00:00:57,660 --> 00:01:00,630 For example, if I wanted to set that to 512, 26 00:01:00,630 --> 00:01:04,800 I could type in ulimit -n 512. 27 00:01:04,800 --> 00:01:09,600 This will then put our limit of 512 maximal open files 28 00:01:09,600 --> 00:01:11,250 for particular user. 29 00:01:11,250 --> 00:01:13,500 You can also display all of your current limits 30 00:01:13,500 --> 00:01:16,620 by issuing the command ulimit -a. 31 00:01:16,620 --> 00:01:18,360 If you want to learn more about ulimit, 32 00:01:18,360 --> 00:01:20,850 go ahead and type in man space u-limit 33 00:01:20,850 --> 00:01:22,110 in your command prompt. 34 00:01:22,110 --> 00:01:23,730 If you want to use it, you're going to type 35 00:01:23,730 --> 00:01:27,390 in ulimit the options and the amount you want to limit. 36 00:01:27,390 --> 00:01:28,770 Now, there's also two commands 37 00:01:28,770 --> 00:01:31,350 to confirm excessive storage space consumption 38 00:01:31,350 --> 00:01:33,930 that might be causing system issues for you. 39 00:01:33,930 --> 00:01:35,163 These are df/du. 40 00:01:36,240 --> 00:01:38,910 The df and du commands are going to facilitate 41 00:01:38,910 --> 00:01:40,800 storage space tracking. 42 00:01:40,800 --> 00:01:44,430 df is going to enable you to view the device's free space, 43 00:01:44,430 --> 00:01:46,590 the file system, the total size, 44 00:01:46,590 --> 00:01:49,800 the space used, the percentage value of space used, 45 00:01:49,800 --> 00:01:51,120 and the mount point. 46 00:01:51,120 --> 00:01:54,390 The du is going to display the device that's being used 47 00:01:54,390 --> 00:01:56,310 including the size of the directory trees 48 00:01:56,310 --> 00:01:58,020 and files within it. 49 00:01:58,020 --> 00:02:00,210 Also enables you to track space hogs. 50 00:02:00,210 --> 00:02:01,260 Those people or directories 51 00:02:01,260 --> 00:02:03,090 that are consuming large amounts of space 52 00:02:03,090 --> 00:02:04,740 on your storage drive. 53 00:02:04,740 --> 00:02:07,380 To run these, you're going to type either du, 54 00:02:07,380 --> 00:02:09,330 the options and the object name 55 00:02:09,330 --> 00:02:12,690 or df, the options and the object name. 56 00:02:12,690 --> 00:02:15,720 Another thing you need to think about is I/O scheduling. 57 00:02:15,720 --> 00:02:18,930 Now, I/O scheduling stands for input/output scheduling, 58 00:02:18,930 --> 00:02:21,240 and it's the process by which the operating system 59 00:02:21,240 --> 00:02:24,120 determines the order of input and output operations 60 00:02:24,120 --> 00:02:26,700 as they pertain to block storage devices. 61 00:02:26,700 --> 00:02:28,440 Scheduling is really important, 62 00:02:28,440 --> 00:02:31,200 because compared to CPU and memory operations, 63 00:02:31,200 --> 00:02:34,170 block storage operations are pretty darn slow 64 00:02:34,170 --> 00:02:36,690 especially if you're using disc based technologies 65 00:02:36,690 --> 00:02:39,120 like old traditional hard discs. 66 00:02:39,120 --> 00:02:40,590 Now there are some different schedulers 67 00:02:40,590 --> 00:02:43,320 that are available for modern Linux kernel versions. 68 00:02:43,320 --> 00:02:45,510 The deadline scheduler performs sorting 69 00:02:45,510 --> 00:02:48,930 of input/output operations, using three different queues. 70 00:02:48,930 --> 00:02:51,150 We have a standard pending request queue, 71 00:02:51,150 --> 00:02:54,210 a read first in, first out queue or FIFO queue, 72 00:02:54,210 --> 00:02:57,270 and a write first in, first out or FIFO queue. 73 00:02:57,270 --> 00:02:59,370 These last two, these two FIFO queues 74 00:02:59,370 --> 00:03:01,260 for reading and writing can be sorted 75 00:03:01,260 --> 00:03:04,890 by the submission time and have expiration values as well. 76 00:03:04,890 --> 00:03:07,200 When a request is submitted, it's going to be sorted 77 00:03:07,200 --> 00:03:09,420 into the standard queue and placed at the end 78 00:03:09,420 --> 00:03:13,020 of the appropriate FIFO queue either for reading or writing. 79 00:03:13,020 --> 00:03:15,390 If the request gets the top of the FIFO queue, 80 00:03:15,390 --> 00:03:17,850 and it becomes older than the queue's expiration, 81 00:03:17,850 --> 00:03:19,380 the schedule will actually stop working 82 00:03:19,380 --> 00:03:21,810 with the standard queue and start servicing requests 83 00:03:21,810 --> 00:03:23,790 from the top of the FIFO queue. 84 00:03:23,790 --> 00:03:27,420 Other words, it wants to handle the oldest request first. 85 00:03:27,420 --> 00:03:29,640 The CFQ scheduler refers 86 00:03:29,640 --> 00:03:33,120 to the Complete Fair Queueing or CFQ scheduler. 87 00:03:33,120 --> 00:03:35,520 Now this scheduler is going to have a process 88 00:03:35,520 --> 00:03:37,380 that's given to each queue and each queue 89 00:03:37,380 --> 00:03:39,780 has an interval by which it's being accessed, 90 00:03:39,780 --> 00:03:41,760 or it's given time slice. 91 00:03:41,760 --> 00:03:44,310 Now, the scheduler's going to use a round robin system 92 00:03:44,310 --> 00:03:46,740 to access each queue and service request 93 00:03:46,740 --> 00:03:47,820 from each of these queues 94 00:03:47,820 --> 00:03:51,360 until their time slices or requests are fully exhausted. 95 00:03:51,360 --> 00:03:54,960 When this happens, the CFQ is going to wait 10 milliseconds 96 00:03:54,960 --> 00:03:57,147 until it sees a new request on the queue. 97 00:03:57,147 --> 00:04:00,090 And if it doesn't, it's going to move on to another queue 98 00:04:00,090 --> 00:04:01,860 so it doesn't waste time. 99 00:04:01,860 --> 00:04:03,660 Now, like the deadline scheduler, 100 00:04:03,660 --> 00:04:06,570 this helps to minimize request starvation. 101 00:04:06,570 --> 00:04:07,800 Another way we can do this 102 00:04:07,800 --> 00:04:11,490 is by using the NOOP Scheduler, N-O-O-P. 103 00:04:11,490 --> 00:04:14,100 Now the NOOP scheduler can be ideal in situations 104 00:04:14,100 --> 00:04:16,079 where the device or its storage controller 105 00:04:16,079 --> 00:04:18,510 performs its own sorting operations. 106 00:04:18,510 --> 00:04:19,740 This can benefit devices 107 00:04:19,740 --> 00:04:21,450 that don't have mechanical components 108 00:04:21,450 --> 00:04:22,920 that require seek time. 109 00:04:22,920 --> 00:04:27,150 Things like SSD, solid state devices or USB flash drives 110 00:04:27,150 --> 00:04:29,670 because this scheduler doesn't expend much effort 111 00:04:29,670 --> 00:04:31,710 in reducing seek time. 112 00:04:31,710 --> 00:04:34,200 Now you, as a system administrator, can actually set 113 00:04:34,200 --> 00:04:37,140 the scheduler that you want to use for particular device 114 00:04:37,140 --> 00:04:39,510 by modifying the scheduler file located 115 00:04:39,510 --> 00:04:44,510 at /sys/block/ whatever the device is /queue/scheduler. 116 00:04:45,840 --> 00:04:48,360 So for example, if I want to set the NOOP scheduler 117 00:04:48,360 --> 00:04:51,060 as my schedule for my SDA device, 118 00:04:51,060 --> 00:04:53,610 I can do this by setting it into the text file, 119 00:04:53,610 --> 00:04:56,310 and I can do it simply by using the echo command. 120 00:04:56,310 --> 00:05:00,210 I would type echo, space noop, space redirector, 121 00:05:00,210 --> 00:05:01,680 or the carrot to the right, 122 00:05:01,680 --> 00:05:06,680 space /sys/block/sda/queue/scheduler. 123 00:05:08,850 --> 00:05:11,250 This sets the scheduler for runtime only 124 00:05:11,250 --> 00:05:14,280 and this setting will revert next time I reboot the system. 125 00:05:14,280 --> 00:05:16,470 If I want to make persistent changes, though, 126 00:05:16,470 --> 00:05:19,860 I have to modify the system's boot loader configuration. 127 00:05:19,860 --> 00:05:21,480 Another utility we need to talk about 128 00:05:21,480 --> 00:05:24,810 is iostat or input/output statistics. 129 00:05:24,810 --> 00:05:27,717 The iostat utility generates reports on CPU 130 00:05:27,717 --> 00:05:29,340 and device usage. 131 00:05:29,340 --> 00:05:32,550 For storage, it's going to provide input and output statistics 132 00:05:32,550 --> 00:05:34,830 for blocked devices and partitions. 133 00:05:34,830 --> 00:05:37,500 Oftentimes, you'll hear input/output operations 134 00:05:37,500 --> 00:05:41,310 per second use, which is I-O-P-S or IOPS. 135 00:05:41,310 --> 00:05:43,710 When you have low IOPS, this means that you have 136 00:05:43,710 --> 00:05:45,660 a very low amount of input and output 137 00:05:45,660 --> 00:05:47,430 operations happening per second, 138 00:05:47,430 --> 00:05:49,290 and there's a slowdown in your system. 139 00:05:49,290 --> 00:05:52,230 To identify this, you can use a tool like iostat 140 00:05:52,230 --> 00:05:53,940 to see what are you currently generating 141 00:05:53,940 --> 00:05:55,410 in terms of input/output, 142 00:05:55,410 --> 00:05:57,690 and then you can identify ways to speed that up 143 00:05:57,690 --> 00:05:58,590 and increase that number 144 00:05:58,590 --> 00:06:01,050 of input/output operations per second. 145 00:06:01,050 --> 00:06:03,780 There are lots of different options when using iostat. 146 00:06:03,780 --> 00:06:06,270 For example, you can use the -D option 147 00:06:06,270 --> 00:06:08,760 to specify the device information only. 148 00:06:08,760 --> 00:06:10,800 The iostat command in this case will list 149 00:06:10,800 --> 00:06:13,560 the following statistics for each storage device, 150 00:06:13,560 --> 00:06:17,010 including its transfers or I/O requests per second, 151 00:06:17,010 --> 00:06:20,310 as tps, the number of blocks read per second 152 00:06:20,310 --> 00:06:22,140 in kilobytes read per second. 153 00:06:22,140 --> 00:06:23,910 The number of blocks written per second 154 00:06:23,910 --> 00:06:25,950 in kilobytes written per second. 155 00:06:25,950 --> 00:06:27,840 The number of total blocks read 156 00:06:27,840 --> 00:06:29,220 which is kilobytes read, 157 00:06:29,220 --> 00:06:30,930 and the total number of blocks written, 158 00:06:30,930 --> 00:06:32,700 which is kilobytes written. 159 00:06:32,700 --> 00:06:35,370 You can use this report to monitor how the storage drive 160 00:06:35,370 --> 00:06:38,850 is being used and to identify any potential bottlenecks. 161 00:06:38,850 --> 00:06:41,400 For example, you might have a faulty drive, 162 00:06:41,400 --> 00:06:43,020 and it can have lower read speeds 163 00:06:43,020 --> 00:06:45,900 or lower write speeds per second, than you're expecting. 164 00:06:45,900 --> 00:06:48,210 If you use this report, it can help you decide 165 00:06:48,210 --> 00:06:50,730 how to best distribute the input/output load 166 00:06:50,730 --> 00:06:53,220 between the different available devices you have. 167 00:06:53,220 --> 00:06:55,110 To run the iostat command, 168 00:06:55,110 --> 00:06:57,330 you're simply going to type in iostat, 169 00:06:57,330 --> 00:06:59,700 the options and the device name. 170 00:06:59,700 --> 00:07:01,230 Now, another command we need to talk about 171 00:07:01,230 --> 00:07:04,560 is ioping, the ioping command generates 172 00:07:04,560 --> 00:07:08,400 a report of device input/output latency in real time. 173 00:07:08,400 --> 00:07:10,920 It's going to continuously ping the specified device 174 00:07:10,920 --> 00:07:12,900 with a request and then print the information 175 00:07:12,900 --> 00:07:15,480 about each request at your command line. 176 00:07:15,480 --> 00:07:17,520 By default, this information tracks 177 00:07:17,520 --> 00:07:20,970 how long it took for an input/output request to finish. 178 00:07:20,970 --> 00:07:23,190 Aside from specifying a device to test, 179 00:07:23,190 --> 00:07:25,560 you can also specify a path name to test 180 00:07:25,560 --> 00:07:28,350 whatever device is associated with that path, 181 00:07:28,350 --> 00:07:30,990 so you can consider using ioping 182 00:07:30,990 --> 00:07:33,780 to troubleshoot latency issues with storage devices, 183 00:07:33,780 --> 00:07:36,180 especially if you believe your read or right speeds 184 00:07:36,180 --> 00:07:38,160 are slower than they really should be. 185 00:07:38,160 --> 00:07:40,830 To do this simply type in ioping, 186 00:07:40,830 --> 00:07:44,010 the options and the file directory or device name. 187 00:07:44,010 --> 00:07:45,300 Now there's some options you can use 188 00:07:45,300 --> 00:07:46,980 with the ioping command. 189 00:07:46,980 --> 00:07:49,230 Things like -c and the count. 190 00:07:49,230 --> 00:07:51,090 This will be used to specify the number 191 00:07:51,090 --> 00:07:53,400 of input/output requests that you want to perform 192 00:07:53,400 --> 00:07:55,140 before stopping automatically. 193 00:07:55,140 --> 00:07:58,260 So you might send 10 requests and see what that looks like. 194 00:07:58,260 --> 00:08:00,720 You can also use -I and time. 195 00:08:00,720 --> 00:08:02,610 This is used to set the time interval 196 00:08:02,610 --> 00:08:04,860 between those input/output requests. 197 00:08:04,860 --> 00:08:07,170 You might also use -t and the time. 198 00:08:07,170 --> 00:08:09,750 This is used to set a minimum valid request time 199 00:08:09,750 --> 00:08:12,480 so requests faster than this are going to be ignored. 200 00:08:12,480 --> 00:08:14,760 If you use dash capital T and time, 201 00:08:14,760 --> 00:08:17,490 this is going to be used to set the maximum valid request time, 202 00:08:17,490 --> 00:08:20,340 so any request that are slower than this will be ignored. 203 00:08:20,340 --> 00:08:23,160 And finally, if you use -s and size, 204 00:08:23,160 --> 00:08:24,930 this is going to set the size of the request 205 00:08:24,930 --> 00:08:27,840 that you're sending using the ioping command. 206 00:08:27,840 --> 00:08:29,370 Now, when we talk about storage, 207 00:08:29,370 --> 00:08:31,980 we need to talk about the idea of storage quotas. 208 00:08:31,980 --> 00:08:34,350 Now, a storage quota is the storage space 209 00:08:34,350 --> 00:08:36,750 that's allocated to a user for file storage 210 00:08:36,750 --> 00:08:38,039 on a computer. 211 00:08:38,039 --> 00:08:41,490 Storage quotas are going to be configured on a per user basis. 212 00:08:41,490 --> 00:08:43,320 And if you use these, it can actually prevent 213 00:08:43,320 --> 00:08:45,030 a lot of issues for you. 214 00:08:45,030 --> 00:08:46,710 If you start doing this, you're going to be able 215 00:08:46,710 --> 00:08:49,620 to prevent issues with people using excessive storage space 216 00:08:49,620 --> 00:08:51,390 and eating up all of the storage 217 00:08:51,390 --> 00:08:53,220 so the system can't operate. 218 00:08:53,220 --> 00:08:54,630 You can use these quotas to ensure 219 00:08:54,630 --> 00:08:57,360 that your users are not consuming all of your drive space 220 00:08:57,360 --> 00:09:00,300 and leaving none for any other users on the system. 221 00:09:00,300 --> 00:09:02,970 Remember quota management is an effective allotment 222 00:09:02,970 --> 00:09:06,300 and monitoring of all the quotas for all of your users. 223 00:09:06,300 --> 00:09:07,800 Linux has a lot of different commands 224 00:09:07,800 --> 00:09:10,170 that can help you ease the job of quota management 225 00:09:10,170 --> 00:09:11,910 as a system administrator. 226 00:09:11,910 --> 00:09:13,350 For example, we have quotacheck, 227 00:09:13,350 --> 00:09:17,820 and if you use quotacheck -cug and the mount point, 228 00:09:17,820 --> 00:09:19,860 this command will actually create quota-based 229 00:09:19,860 --> 00:09:21,990 database files for the file system, 230 00:09:21,990 --> 00:09:24,870 and then check the users and group quotas against it. 231 00:09:24,870 --> 00:09:28,200 Now, if you use edquota -u, username, 232 00:09:28,200 --> 00:09:31,410 this is going to be used to edit quotas for a specific user. 233 00:09:31,410 --> 00:09:34,740 If you use edquota -g and the group name, 234 00:09:34,740 --> 00:09:38,250 this will be used to edit these quotas for a specific group. 235 00:09:38,250 --> 00:09:41,010 If you use setquota -u and the username, 236 00:09:41,010 --> 00:09:44,040 this is going to be used to set quotas for specific user. 237 00:09:44,040 --> 00:09:46,890 If you use setquota -g group name, 238 00:09:46,890 --> 00:09:49,740 this will be able to set quotas for a specific group. 239 00:09:49,740 --> 00:09:51,540 Now, before you can use any of these commands, 240 00:09:51,540 --> 00:09:53,850 you have to activate user and group quotas 241 00:09:53,850 --> 00:09:55,320 on the file system. 242 00:09:55,320 --> 00:09:58,140 And to do this, you'll edit your fstab file 243 00:09:58,140 --> 00:10:00,690 and add the options, usrquota 244 00:10:00,690 --> 00:10:04,170 or grpquota to the relevant file system. 245 00:10:04,170 --> 00:10:07,800 Now, you can also use your xfs_admin utility 246 00:10:07,800 --> 00:10:11,640 to configure quotas if you're using an XFS file system. 247 00:10:11,640 --> 00:10:12,720 This utility can run 248 00:10:12,720 --> 00:10:15,450 in both interactive and non interactive mode. 249 00:10:15,450 --> 00:10:17,460 If you're running it non interactively, 250 00:10:17,460 --> 00:10:19,890 you can use the -c option to specify 251 00:10:19,890 --> 00:10:21,150 which commands to run, 252 00:10:21,150 --> 00:10:24,060 and the -x options to enable expert mode 253 00:10:24,060 --> 00:10:26,910 which is required for many of the administrative tasks. 254 00:10:26,910 --> 00:10:29,880 Tasks inside the XFS admin utility include things 255 00:10:29,880 --> 00:10:32,580 like setting limits on writing blocks and iNodes, 256 00:10:32,580 --> 00:10:35,220 setting warning limits, generating quarter reports, 257 00:10:35,220 --> 00:10:36,630 and much more. 258 00:10:36,630 --> 00:10:39,360 Now quarter reports are going to be created by the system 259 00:10:39,360 --> 00:10:41,340 so you can view storage space that's being used 260 00:10:41,340 --> 00:10:42,780 by each person. 261 00:10:42,780 --> 00:10:44,880 These reports enable you to check which user 262 00:10:44,880 --> 00:10:47,250 is taking up the most disk space. 263 00:10:47,250 --> 00:10:49,050 This can also help you troubleshoot issues 264 00:10:49,050 --> 00:10:50,550 with the quotas themself. 265 00:10:50,550 --> 00:10:52,860 For example, quotas may be too restrictive 266 00:10:52,860 --> 00:10:54,240 or too permissive. 267 00:10:54,240 --> 00:10:56,670 A quota report is going to contain the name of the user 268 00:10:56,670 --> 00:10:59,400 or group, the total number of blocks in kilobytes 269 00:10:59,400 --> 00:11:01,050 that are being used by that user or group 270 00:11:01,050 --> 00:11:04,500 in the file system, the user or group storage soft limit, 271 00:11:04,500 --> 00:11:07,830 the user or group storage hard limit, the grace period, 272 00:11:07,830 --> 00:11:09,690 the total number of iNodes that have been used 273 00:11:09,690 --> 00:11:12,240 by the file system by that user or group, 274 00:11:12,240 --> 00:11:14,100 the soft limit on those iNodes, 275 00:11:14,100 --> 00:11:16,290 and the hard limit on those iNodes. 276 00:11:16,290 --> 00:11:17,760 Now, there are several commands available 277 00:11:17,760 --> 00:11:20,490 for the generation of effective quota reports. 278 00:11:20,490 --> 00:11:22,830 This includes things like rep quota. 279 00:11:22,830 --> 00:11:25,560 Now the rep quota -a command is going to be used 280 00:11:25,560 --> 00:11:28,500 to display the reports for all the file systems indicated 281 00:11:28,500 --> 00:11:32,010 as read or write with quotas in the mtab file. 282 00:11:32,010 --> 00:11:34,740 repquota -u, and the username will display 283 00:11:34,740 --> 00:11:37,200 the quota reports for particular user. 284 00:11:37,200 --> 00:11:40,260 If you use quota -uv, and the username, 285 00:11:40,260 --> 00:11:42,630 this command will be used to display the quota report 286 00:11:42,630 --> 00:11:45,570 for a particular user with verbose output. 287 00:11:45,570 --> 00:11:46,733 If you use warnquota -u, 288 00:11:47,730 --> 00:11:49,200 this command will be used to check 289 00:11:49,200 --> 00:11:52,620 if a user are not exceeding the allocated quota limit. 290 00:11:52,620 --> 00:11:56,100 And if you use warnquota -g, this'll check if any groups 291 00:11:56,100 --> 00:11:59,070 are not exceeding the allocated quota limit. 292 00:11:59,070 --> 00:12:00,810 Now when troubleshooting storage issues, 293 00:12:00,810 --> 00:12:02,640 you should always start out with the simple things 294 00:12:02,640 --> 00:12:04,920 and then move towards the complex things. 295 00:12:04,920 --> 00:12:06,960 Make sure your devices are physically connected 296 00:12:06,960 --> 00:12:09,750 to the system when your troubleshooting storage issues. 297 00:12:09,750 --> 00:12:11,610 I've seen a lot of times where the device simply 298 00:12:11,610 --> 00:12:13,740 isn't even connected or powered on. 299 00:12:13,740 --> 00:12:15,780 So make sure you've checked that it's powered, 300 00:12:15,780 --> 00:12:18,090 verify the device is recognized by the system 301 00:12:18,090 --> 00:12:20,340 by checking the slash proc directory. 302 00:12:20,340 --> 00:12:22,170 Confirm that the configuration files 303 00:12:22,170 --> 00:12:24,720 don't contain any typographical errors. 304 00:12:24,720 --> 00:12:27,540 Also ensure the configuration files have been loaded 305 00:12:27,540 --> 00:12:29,070 if you made changes to them 306 00:12:29,070 --> 00:12:31,380 and confirm there's enough storage capacity, 307 00:12:31,380 --> 00:12:33,780 as well as confirming the input/output workload 308 00:12:33,780 --> 00:12:35,730 is not overwhelming your devices, 309 00:12:35,730 --> 00:12:37,950 and you can always use the part probe command 310 00:12:37,950 --> 00:12:40,410 to enable the system to scan for new storage devices 311 00:12:40,410 --> 00:12:44,040 and partitions and load those files back into the kernel. 312 00:12:44,040 --> 00:12:46,470 This is all some of the basic stuff you need to check 313 00:12:46,470 --> 00:12:49,473 to make sure your storage devices are working optimally.