1 00:00:00,000 --> 00:00:12,440 In this video, you will learn about SAR, the System Activity Reporter. It shows system 2 00:00:12,440 --> 00:00:17,680 usage statistics that have been gathered over a longer period of time. And SAR is relevant 3 00:00:17,680 --> 00:00:22,280 because a utility like TOP will only show you what is happening here and now. And the 4 00:00:22,280 --> 00:00:28,639 best thing TOP can do is show you the last 1, 5 and 15 minute system usage averages. 5 00:00:28,639 --> 00:00:35,720 SAR can gather information about everything and it gives you long-term trends on the utilization 6 00:00:35,720 --> 00:00:41,919 of your computer. Now, these statistics are collected by the SA1 and SA2 programs and 7 00:00:41,919 --> 00:00:48,599 they are executed as scheduled jobs, either using CROM or system D timers. And to work 8 00:00:48,599 --> 00:00:53,599 with SAR, you need to verify that data gathering by these utilities is enabled. Let me show 9 00:00:53,599 --> 00:00:59,520 you. So to start with, I need to install the SysTat package. Here on the CentOS system, 10 00:00:59,520 --> 00:01:07,120 I'm using sudo dnf install –y systat. Next, when I'm using SAR with one of the many options 11 00:01:07,120 --> 00:01:13,160 like SAR-A, what do we see? Oh no, we see cannot open VARLOG SA-SA30, no search file 12 00:01:13,160 --> 00:01:18,519 or directory. Why is that? Well, that is because I've just installed the package, but in order 13 00:01:18,519 --> 00:01:26,839 to work with SAR, you need to do some data gathering. So let me use systemctl listunit 14 00:01:26,839 --> 00:01:32,720 files –d timers so that you can see all the system D timers and there we can see that 15 00:01:32,720 --> 00:01:38,720 there is the SysTat collect timer. And SysTat collect timer is what we need here. You can 16 00:01:38,720 --> 00:01:42,919 see it's enabled, but it's a scheduled job. And as a scheduled job, you will always need 17 00:01:42,919 --> 00:01:52,279 to wait for a little bit. But if we use systemctl cat on systat collect.service, that is the 18 00:01:52,279 --> 00:01:57,519 program that is triggered by the timer. There we can see what it is doing. So this is the 19 00:01:57,519 --> 00:02:03,720 command that it is running. So you know what I'm going to do? I'm going to run it manually 20 00:02:03,720 --> 00:02:11,080 using sudo because we need sudo privileges to do so. And here it is going to run. And 21 00:02:11,080 --> 00:02:17,360 then I'm going to wait for one minute. So the minute is over, and I'm going to run 22 00:02:17,360 --> 00:02:24,600 my data gatherer again. Now, why do I do that? Let me show you. I'm doing this because in 23 00:02:24,600 --> 00:02:32,520 the var log directory, it should have created the SA directory. And in this SA directory, 24 00:02:32,520 --> 00:02:40,160 we can see the file SA30. Why is that SA30? Well, because today is the 30th. And in the 25 00:02:40,320 --> 00:02:46,919 SA30 file, we are able to find the data that has been gathered. So this is just a one-time 26 00:02:46,919 --> 00:02:52,320 data gathering. It's only four kilobytes, but it's only just starting. And the result is that 27 00:02:52,320 --> 00:02:59,720 right now I can use SAR minus A, and SAR minus A is giving me all the information. And that 28 00:02:59,720 --> 00:03:06,240 includes CPU utilization. It includes network interface utilization. It includes storage 29 00:03:06,240 --> 00:03:12,759 device utilization, and so much more. Now, as you can see, the first time I've used my data 30 00:03:12,759 --> 00:03:18,479 gathering, it has created the header lines. It didn't really write any data. Only the second 31 00:03:18,479 --> 00:03:25,759 time, it has written any data to it. And next, when this is growing a little bit and you get 32 00:03:25,759 --> 00:03:32,679 more information, use SAR with one of the many, many commands that are available. Like, for 33 00:03:32,679 --> 00:03:40,360 instance, SAR minus R all, which is doing what? Which is giving memory utilization statistics. I 34 00:03:40,360 --> 00:03:45,679 would say knock yourself out in SAR minus minus L with all the different options that you can 35 00:03:45,720 --> 00:03:53,520 request here. Every single aspect of system utilization can be queried. And when multiple 36 00:03:53,520 --> 00:03:59,639 datasets have been gathered, you see a nice list. And the thing in this nice list is that you can 37 00:03:59,639 --> 00:04:06,039 see an average. And the average, well, based on one-time data gathering is not so very exciting. 38 00:04:06,639 --> 00:04:12,720 The exciting part is that you can see trends. So if you suspect your server to peak every night at 39 00:04:12,720 --> 00:04:19,040 2am, well, SAR is going to reveal it. And that is what makes this utility so incredibly useful.