Remote Computing On a Linux application server farm

Article Title: Remote Computing On a Linux application server farm. Linux is a technology channel of the IT lab in China. Includes basic categories such as desktop applications, Linux system management, kernel research, embedded systems, and open source.

You have heard of Web 2.0, right? Well, this is "utility computing 2.0", which is a network boot, SSL, VNC, and other familiar concepts and technologies-all of these technologies are in Linux? -It can bring a great return on investment. Learn how the University of California sets up a server farm environment to provide students with secure remote desktop applications.

Save thousands of dollars. Significantly improve system availability. Enhance security. Simplify maintenance operations. Reduces dependencies on a single source or expensive component. Simplify license authorization.

Even if a development project only implements the above advantages, we will be very happy. What we call "utility computing 2.0" has all of the above advantages.

By integrating a group of individual common technologies, you will be greatly benefited. When using them separately, no technology can provide significant advantages. If you use a completely different but overlapping combination of technologies for different projects, the situation will become more complex. This article describes how to use network guidance, low power computing, VNC, and SSL to implement technology integration in a project.

Network-guided University computing laboratory

The Engineering School at the University of California's Merced (UCM) maintains two computing labs for 60 people, where students can complete their homework. A lab has common Windows®XP desktop host, but in the last update process, the lab switched to the ITX Mini-Box M200 drive for the 24 inch Dell LCD display, with the resolution set to 1280x1024. The cost of these seats is only USD 1,138, or even can be purchased separately. Table 1 compares the costs of Mini-Box and traditional desktop systems.

Table 1. Basic desktop costs

Project	Mini-Box	Traditional desktop
CPU	$275	$1,100
24 inch display	$747	$747
Mouse, keyboard	$36	$36
1 GB memory	$80	$180
Standard Power Consumption	15	200

The default workstation cost that can be purchased for the lab is about twice: $2,063. In addition, the average monthly savings of about 100 watts of power can be saved by about 10 US dollars, or about 100 US dollars a year, based on California's major electricity prices. If we consider the reduced power load of the laboratory's air-conditioning equipment, the savings may even exceed three times. You can also look at this problem in another way: CPU savings make it possible for a 24 inch display. These thin and wide clients are very popular.

On the other hand, the speed of a standard workstation is about three times that of a small Mini-Box. However, this is not a problem because the lab computers are fast enough for their work. The main tasks of these computers are: basic report preparation, email, Web research, school development assignments, and remote result display.

The following describes how these hosts operate at the system level. Each seat is set to network boot from a boot server. All machines are basically the same. It takes about 73 seconds to boot Ubuntu Linux 2.6 using the built-in PXE loader. Each workstation obtains read-only workspace loaded using NFS during the boot process. As part of the boot process, UnionFS uses tmpfs to create a read/write root file system. Once the user logs on (it takes 23 seconds), they can see their main file system in/home/username, which is the link to the mount point.

Log on to, log out, and browse the system

After a seat is guided, a Common Logon prompt is displayed. However, getty is not connected to/etc/passwd or LDAP, but to SSH! The/etc/inittab shared by each seat includes the following content;

Listing 1. Bootstrap start getty

1:2345:respawn:/sbin/rungetty -u root tty1 /usr/local/sbin/UCM_login

/Usr/local/sbin/UCM_login is a Python script of about 300 lines. It:

• Load all login information in the screen so that remote debugging can be performed.
• Set specific timeout, logon, terminal drivers, and related "daily management" configuration variables
• Interacts with the status server, which is responsible for overall monitoring of the laboratory
• Print welcome and usage messages
• Prompt User Logon

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