Red Hat certified engineers (RHCE) for Linux Learning

Linux, as an operating system software, serves as a bridge between computer system hardware and application software. Learning RHCE should also begin with hardware. However, the operating system is software after all, so you only need to know some basic hardware knowledge. In fact, the understanding of these basic hardware knowledge not only helps the system administrator to configure Linux well, but also helps solve many faults on the Linux system.★System Architecture we know that Linux is famous for supporting a large number of system architectures. However, for RH

Linux, as an operating system software, serves as a bridge between computer system hardware and application software. Learning RHCE should also begin with hardware. However, the operating system is software after all, so you only need to know some basic hardware knowledge. In fact, the understanding of these basic hardware knowledge not only helps the system administrator to configure Linux well, but also helps solve many faults on the Linux system.

★System Architecture)

We know that Linux is famous for supporting a large number of system architectures. However, for RHCE, you only need to consider the Intel architecture (i386) that can be supported by normal PCs, thus avoiding the trouble of learning the system architecture-related knowledge.

★Intel communication channel

Generally, the following three channels are supported on a PC:

1) interrupt request port (IRQ): it is mainly used for interrupt request service for keyboards, printers, and other devices.

2) Input/Output address: the memory address for the CPU to communicate with other parts of the computer.

3) Direct Memory Access Channel (DMA): it is mainly used for computer devices with independent processors.

Because RedHat supports plug and play well, the configurations related to these channels are almost transparent to the system administrator. However, learning them will help us solve some special faults. Next, let's take a look at the relevant information:

1) IRQ setting: According to the accurate definition, IRQ is the request signal sent when a peripheral device (such as the NIC, mouse, serial port, etc.) sends a request to the CPU for processing time. Generally, each connected device on the computer needs its own IRQ port, and this port is always in use (except for mobile devices ). If IRQ is exhausted, some PCI devices and USB devices can share IRQ.

Practice Analysis: if there is a problem with the USB port or PCI card on the machine, first check the BIOS. Many BIOS options include "activating PCI sharing" and "supporting USB connections.

2) IRQ conflicts: IRQ is a valuable resource in some PCs. As the number of connected devices increases, IRQ conflicts may occur. If a conflict occurs, you can manually set IRQ. If no IRQ is available, you must sacrifice a connection device. It should be noted that some IRQ cannot be modified because they are reserved for the control devices on the master board and do not conflict with them. In Linux, you can view/proc/interrupts to see which interrupts are used and which ones are not yet used.

3) Input/Output address: each computer device requires an input/output address, which is the location where data requested by the CPU service is stored. I/O addresses are generally listed in hexadecimal notation. Some typical I/O addresses, such as serial COM1, COM2, COM3, and COM4, correspond to the I/O addresses 03f8, 02f8, 03e8, and 02e8 respectively. In Linux, you can browse/proc/ioports to view the allocated I/O address.

4) Direct Memory Address: This address is usually used to transmit information directly between devices without passing through the CPU. Many parts of modern PCS do not require CPUs, such as sound cards and video cards. Although DMA channels do not require CPU intervention, these devices are still configured with IRQ ports, with eight standard DMA channels (0-7 ). Note that DMA 4 is retained and cannot be used on any device. In Linux, you can browse/proc/dma to view the allocated DMA address.

★Memory

For Redhat Enterprise Linux 5 (RHEL 5), the minimum memory requirement is 256 MB (actually it can be smaller, but the memory is too small to meet the normal operating requirements of the system ).

RHEL 5 supports a large amount of memory. Generally, the memory limit comes from hardware.

Practical Analysis: For Linux servers, the system's memory requirements increase with the increase of the number of users, and those large programs, such as databases, consume a lot of memory.

★Hard Disk

The Linux system is installed on the hard disk. Obviously, the hard disk supports the system very closely. From the hardware point of view, you should understand:

1) A standard PC can only manage up to four IDE drives and cannot recognize the PATA drive.

2) the updated PC can control more SATA drives.

3) If SCSI hardware is supported, the machine can support up to 31 SCSI drives.

4) no matter how many PATA, SATA, or SCSI drives are used, the Linux Startup File (in the/boot directory) must be installed on the first two hard disks. Otherwise, you must use a drive floppy disk to start the system.

5) Although Linux can be installed on a USB or IEEE 1394 hard drive, it cannot be started directly from these drives.