Installing RHEL5.3 is two new terms

 

This evening, I downloaded an RHEL5.3 iso file from the school Ftp and installed it on the virtual machine. I don't know what it means when I encounter two nouns. Google.

 

"To create a RAID device, you must first create (or reuse existing) software RAID partitions. Once you have created two or more software RAID partitions, select RAID to connect the software RAID partition to a RAID device ." --- Installation strategy.

 

1. RAID device

 

RAID combines several physical disks into a large virtual physical disk. The main purposes and purposes of RAID are as follows: make several small-capacity physical disks into a large-capacity virtual storage device (the previous physical disk capacity is relatively small); improve the physical storage efficiency (read and write ), or provide redundancy to improve data storage security. A Case for Redundant Arrays of Inexpensive Disks (RAID), translated in Chinese as A disk array. RAID can also be divided into hardware RAID and software RAID. Hardware RAID aggregates several hard disks of the same size into a large virtual RAID device (or RAID 0, or RAID 1, or RAID 5, or RAID 10…) through a RAID card ......), If the capacity of each hard disk is inconsistent, it is based on the hard disk with the minimum capacity; its members are the entire hard disk. Soft RAID aggregates several hard disks or partitions of the same size into a large virtual RAID device (or RAID 0, or RAID 1, or RAID 5, or RAID 10 ......), If the capacity of each hard disk or partition is inconsistent, the minimum capacity of the hard disk or partition is used as the basis. The members of the soft RAID are the entire hard disk or partition.

 

The features of RAID0, RAID1, RAID5, and RAID10 are not the same. For example, the RAID0 capacity is the total capacity of all members added to RAID0, while the RAID1 device is the capacity of a single member ...... Security and other features are different. The details are not described in detail. It is useless to remember more. You can also build the RAID on your own in linux. Search for the RAID when using the command line. Now I can understand more about it.

 

"LVM": allows you to create an LVM logical volume. LVM (logical volume manager) is used to display a simple logical view of basic physical storage space, such as a hard disk. LVM manages a single physical disk-or, more specifically, a single partition on the disk. It should be used only when you have experience using LVM. To create an LVM logical volume, you must first create a partition of the physical volume type (LVM. Once you have created one or more physical volume (LVM) partitions, select "LVM" to create the LVM logical volume ." ----- Installation strategy

 

2. LVM logical volume manager

 

Its function is to dynamically allocate disk partitions and make multiple partitions or physical hard disks as a logical volume (equivalent to a logical hard disk). How do I feel like the RAID above? You can learn more about this ). In previous Linux systems, when a disk is connected to a server, fdisk is used to divide it into primary partitions and extended partitions. Then, the partition is formatted to generate partitions such as/dev/sda1 and/dev/sda2. These partitions can be directly mounted to a directory using the mount command. When LVM is applied, the disk partition/dev/sda1 and/dev/sda2 are considered as a whole VG (Virtual Disk) by LVM ). Such a volume group cannot be directly attached. It must be converted from LVM to a VG volume group such as/dev/VolGroup01; then, each volume group contains an LV such as/dev/VolGroup01/LogVol01, that is, a logical volume. When using them, you need to mount/dev/VolGroup01/LogVol01 to the directory. Based on this, LVM provides the ability to adjust the partition (volume) size.