If you're as comfortable with NetWare services as you are in your favorite old jeans, we've got good news: the NetWare services you've grown to know and love are also available on Novell Open Enterprise Server for Linux. The arguably better news is that getting and keeping Open Enterprise Server for Linux up and running is easier than you might think–and this series intends to prove it to you.
This is the eighth article in a nine-part series designed to help you bridge your NetWare skills to Open Enterprise Server for Linux. Like Novell's free training program upon which it is based, this series seeks to demystify the process of deploying and managing Open Enterprise Server for Linux. (See novell.com/products/openenterpriseserver/migrate.html.)
The first three articles in this series provide primarily background information, including a summary of the Linux history, a discussion of Linux fundamentals, and an introduction to Novell Open Enterprise Server. (If you haven't already, check these out: See "Got Skills?" Novell Connection Online, January 2006, "Back to Basics," Novell Connection, Q1 2006, Novell Connection Magazine, March 2006, Tech Talk #2.)
Parts 4 and 5 in this series move beyond this necessary foundation and take the first big steps toward achieving the series' goal. Bridging the gap between your NetWare know-how and Linux naivete, Part 4 walks through commonly-used NetWare tasks to highlight their functional equivalents on Open Enterprise Server for Linux. (See "Got Skills? Bridge 'Em to Linux Part 4".) Further illustrating that NetWare knowledge serves you well in a Novell Linux environment, Part 5 discusses two familiar server management tools for Open Enterprise Server for Linux: Novell Remote Manager for Linux and Novell iManager 2.5. (See "Got Skills? Bridge 'Em to Linux Part 5".)
Parts 6 and 7 work in tandem to increase your understanding of the Linux file system. Part 6 introduces Linux file system choices, structure and commands. (See "Got Skills? Bridge 'Em to Linux Part 6.") Part 7 hones in on aspects of the file system that might confuse or prove particularly interesting to you and anyone else with a history of NetWare administration. Discussion points in part 7 include Linux disk partitions, Novell Storage Services and file-system access control. (See "Got Skills? Bridge 'Em to Linux Part 7.")
This article discusses some of the tools and command-line utilities you will use to monitor the Linux operating system.
Checking On Processes and Connections
At this point in this series, you have learned already that running Open Enterprise Server for Linux enables you to use on Linux many of the same utilities you have used to manage NetWare. Monitoring server processes and connections poses no exception to this rule. You can monitor server processes and connections on Linux using a tool with which you have grown familiar on NetWare: Novell Remote Manager (NRM, pronounced 'Norm'). (For more information about NRM, see Part 5 in this series at novell.com/connectionmagazine/2006/05/tech_talk_2.html.)
What you might not know is that Open Enterprise Server for Linux offers additional utilities for monitoring server processes, including top, ps, pstree and K Desktop Environment (KDE) System Guard.
When you enter the top command from the Linux command prompt, this utility returns a list of the processes that "top" the process pile in terms of their CPU or memory use. (See Figure 1.) As you can see in Figure 1, the top utility displays these processes by process ID (PID). At the top of the screen, you find information such as how many users are connected; the average load for the last few minutes; running tasks, and CPU, memory and swap statistics. For each listed process, top shows the percentage of CPU and memory consumed, alongside other information. The results of top are updated every few seconds.
If you are less concerned with which processes are hogging server resources and more concerned with ascertaining which processes are simply running, then use either ps or pstree. Each of these utilities returns a list of processes running on the server. The process command, ps, displays a static list of running processes. The process tree command, pstree, displays a dynamic list of running processes and their subprocesses. From these lists, you can send commands to control processes. For example, using the kill command in conjunction with a PID, you can stop a running process from within ps or pstree.
You also can retrieve a list of the processes running on your Linux server using KDE System Guard. To access it, click the Novell button (the green button with the N on it in the left corner of the KDE interface). Then you choose Monitor from the System pull-down menu. (See Figure 2.)
KDE System Guard provides a one-stop graphical shop for viewing and managing with ease and convenience the processes running on your server. From KDE System Guard you can view a list of all running processes, system processes only or even only your own processes. You also can see which processes started which other processes in a format similar to what you see using pstree. You can control processes with ease from KDE System Guard. For example, to stop a process from within KDE System Guard, simply highlight the process and press Kill.
To monitor open files and user connections on Linux, you can use the familiar standby NRM or use a Linux utility, such as fuser, lsof, who and w.
- fuser shows which users are accessing which files.
- lsof lists open files, their size, their parent program, the users accessing them and these users' locations.
- who shows who is logged in to your system.
- w shows more information about who is logged in to your Linux box, such as user names, when users logged in and how much CPU each user is consuming.
The bottom line is this: to monitor processes, connections and users on Linux, you can take the familiar route, via NRM, or the new route, via Linux command-line utilities.
Here's to Server Health
Monitoring the health of a Linux server offers the same choice: to do so, you can use familiar tools—in this case, NRM or Health Monitoring Services in iManager 2.5—or you can use new utilities available only on Linux, such as KDE System Guard.
KDE System Guard enables you to monitor various aspects of server health. For example, by default, KDE System Guard provides real-time information regarding current CPU load, load average and physical and swap memory use. (See Figure 3.) The potential downside to KDE System Guard is that running it adds significantly to the CPU load.
To avoid this potential strain on your CPU, you can use command-line utilities to monitor server health, such as free and uptime. The free command enables you to check various statistics regarding memory, such as total memory available, amount used and amount free. As its name suggests, uptime enables you to monitor your system's uptime. Like the top line in top, uptime shows you how long the system has been up, how many users are logged in and the load average for the last several minutes.
You also can view CPU information using the cat command. To do so, enter cat /proc/cpuinfo from the command prompt. This command returns information such as CPU vendor, model and megahertz. To weed through the wealth of information available in /proc, use the procinfo command. This command sorts information from the /proc system and returns a readout in text format.
Unlike monitoring processes, connections and server health, accessing error logs on Linux offers no familiar route. As you probably know, NetWare stores several error logs in SYS:SYSTEM, including Boot$log.err, Sys$log.err, Vol$log.err, Tts$log.err and Abend.log. While you will find these logs in Open Enterprise Server for NetWare, you will have to search elsewhere on Open Enterprise Server for Linux.
Open Enterprise Server for Linux stores most of its error messages in /var/log/messages by default. You can search this file by entering cat /var/log/messages | grep string from the command line.
You also can search kernel messages only when you run into trouble. By default, terminal 10 stores kernel messages, so if you are having a hardware problem, for example, you can press Ctrl-Alt-F10 to view and scan kernel messages.
Open Enterprise Server for Linux also offers the syslog daemon, syslogd, the configuration file for which is in /etc/syslog.conf. This daemon uses the syslog protocol to forward log messages. From the daemon's configuration file, you can set up different categories of error messages, such as kernel, mail or news. (See Figure 4.) You also can ascribe levels of importance to messages, from warnings to critical. You can then indicate for messages of certain importance (for example, critical) whether you want to receive either an e-mail or pop-up message on your terminal when the system logs such a message in /messages.
As you might expect, /messages can grow very large. You have several ways of easily preventing your error logs from filling up your /var partition. For example, you can use a command-line utility called log rotate, which enables you to automate the backup and compression of message lots within the time frame you specify, for example, every hour.
With each of the command-line utilities mentioned in this article, you can use several additional commands and options–far more commands and options than are possible to discuss in this brief article. Peruse the options for yourself by typing in man command name from the Linux command prompt. Doing so launches the Manual (Man) Pages for this command, where you can read about its options and how to make them work for you.
If you were to take the training program on which this series is based, you would be expected at this point to complete several exercises. These exercises offer you the opportunity to practice monitoring processes, connections and server health as well as accessing error logs on Open Enterprise Server for Linux. In addition to enabling you to experience first-hand the command-line utilities mentioned in this article, the exercises also prompt you to use some of the utilities' options not yet discussed. The exercises also prompt you to launch and practice using the graphical KDE System Guard.
The next–and last–article in this series offers you some practical advice about how to further your Linux training.