The scout program runs on any AFS client machine that has access to the curses graphics package, which most UNIX distributions include as a standard utility. It can run on both dumb terminals and under windowing systems that emulate terminals, but the output looks best on machines that support reverse video and cursor addressing. For best results, set the TERM environment variable to the correct terminal type, or one with characteristics similar to the actual ones. For machines running AIX, the recommended TERM setting is vt100, assuming the terminal is similar to that. For other operating systems, the wider range of acceptable values includes xterm, xterms, vt100, vt200, and wyse85.

No privilege is required to run the scout program, so any user who can access the directory where its binary resides (the /usr/afsws/bin directory in the conventional configuration) can use it. The program's probes for collecting statistics do not impose a significant burden on the File Server process, but you can restrict its use by placing the binary file in a directory with a more restrictive access control list (ACL).

Multiple instances of the scout program can run on a single client machine, each over its own dedicated connection (in its own window). It must run in the foreground, so the window in which it runs does not accept further input except for an interrupt signal.

You can also run the scout program on several machines and view its output on a single machine, by opening telnet connections to the other machines from the central one and initializing the program in each remote window. In this case, you can include the -host flag to the scout command to make the name of each remote machine appear in the banner line at the top of the window displaying its output. See The Banner Line.

As previously mentioned, the scout program can monitor the File Server process on any number of file server machines. If all of the machines belong to the same cell, then their hostnames probably all have the same domain name suffix, such as example.com in the Example Corporation cell. In this case, you can use the -basename argument to the scout command, which has several advantages:

The scout program can display statistics either in a dedicated window or on a plain screen if a windowing environment is not available. For best results, use a window or screen that can print in reverse video and do cursor addressing.

The scout program screen has three main regions: the banner line, the statistics display region and the probe/message line. This section describes their contents, and graphic examples appear in Example Commands and Displays.

To draw your attention to a statistic that currently exceed a threshold value, the scout program displays it in reverse video (highlights it). You can set the threshold value for most statistics, and so determine which values are worthy of special attention and which are normal.

Do not resize the display window while the scout program is running. Increasing the size does no harm, but the scout program does not necessarily adjust to the new dimensions. Decreasing the display's width can disturb column alignment, making the display harder to read. With any type of resizing, the scout program does not adjust the display in any way until it displays the results of the next probe.

To resize the display effectively, stop the scout program, resize the window and then restart the program. Even in this case, the scout program's response depends on the accuracy of the information it receives from the display environment. Testing during development has shown that the display environment does not reliably provide information about window resizing. If you use the X windowing system, issuing the following sequence of commands before starting the scout program (or placing them in the shell initialization file) sometimes makes it adjust properly to resizing.

   % set noglob
   % eval '/usr/bin/X11/resize' 
   % unset noglob

This section presents examples of the scout program, combining different arguments and illustrating the screen displays that result.

In the first example, an administrator in the Example Corporation issues the scout command without providing any optional arguments or flags. She includes the -server argument because she is providing multiple machine names. She chooses to specify on the initial part of each machine's name even though she has not used the -basename argument, relying on the cell's name service to obtain the fully-qualified name that the scout program requires for establishing a connection.

   % scout -server fs1 fs2 

Figure 2 depicts the resulting display. Notice first that the machine names in the fifth (unlabeled) column appear in the format the administrator used on the command line. Now consider the second line in the display region, where the machine name fs2 appears in the fifth column. The Conn and Ws columns together show that machine fs2 has 144 RPC connections open to 44 client machines, demonstrating that multiple connections per client machine are possible. The Fetch column shows that client machines have made 2,734,278 fetch RPCs to machine fs2 since the File Server process last started and the Store column shows that they have made 34,066 store RPCs.

Six partition entries appear in the Disk attn column, marked a through f (for /vicepa through /vicepf). They appear on three lines in two subcolumns because of the width of the window; if the window is wider, there are more subcolumns. Four of the partition entries (a, c, d, and e) appear in reverse video to indicate that they are more than 95% full (the threshold value that appears in the Disk attn header).

Figure�2.�First example scout display

In the second example, the administrator uses more of the scout program's optional arguments.

   % scout -server fs1 fs2 -basename example.com -host -frequency 5 -attention disk 5000 

The use of optional arguments results in several differences between Figure 3 and Figure 2. First, because the -host flag is included, the banner line displays the name of the machine running the scout process as [client52] along with the basename example.com specified with the -basename argument.

Another difference is that two rather than four of machine fs2's partitions appear in reverse video, even though their values are almost the same as in Figure 2. This is because the administrator changed the highlight threshold to a 5000 block minimum, as also reflected in the Disk attn column's header. And while machine fs2's partitions /vicepa and /vicepd are still 95% full, they have more than 5000 free blocks left; partitions /vicepc and /vicepe are highlighted because they have fewer than 5000 blocks free.

Note also the result of changing the probe frequency, reflected in the probe reporting line at the bottom left corner of the display. Both this example and the previous one represent a time lapse of one minute after the administrator issues the scout command. In this example, however, the scout program has probed the File Server processes 12 times as opposed to once

Figure�3.�Second example scout display

In Figure 4, an administrator in the State University cell monitors three of that cell's file server machines. He uses the -basename argument to specify the stateu.edu domain name.

   % scout -server server2 server3 server4 -basename stateu.edu 

Figure�4.�Third example scout display

Figure 5 illustrates three of the scout program's features. First, you can monitor file server machines from different cells in a single display: fs1.abc.com, server3.stateu.edu, and sv7.def.com. Because the machines belong to different cells, it is not possible to provide the -basename argument.

Second, it illustrates how the display must truncate machine names that do not fit in the fifth column, using an asterisk at the end of the name to show that it is shortened.

Third, it illustrates what happens when the scout process cannot reach a File Server process, in this case the one on the machine sv7.def.com: it highlights the machine name and blanks out the values in the other columns.

Figure�5.�Fourth example scout display