Linux array RAID details

Main content: (Note summary-it will be supplemented and modified from time to time. if any error occurs, please refer to the discussion) i. RAID description II. mdadm tool introduction III. basic process for creating a RAID IV. disk array management v. RAID optimization RAID description: RAID :( RedundantArrayofindenpensiveDisk) redundant array of independent disks: the disk array refers to multiple

Main content: (Note summary-it will be supplemented and modified from time to time. if any error occurs, please refer to the discussion)

I. RAID details
II. mdadm tool introduction
3. basic process of creating a RAID
IV. disk array management
5. RAID optimization

RAID Details:

Description:RAID :( Redundant Array of indenpensive Disk) independent Redundant Disk Array: a Disk Array is an Array consisting of multiple disks and used as a single Disk. it splits data into segments (striping) storage in different disks. when accessing data, the related disks in the array work together to greatly reduce the data access time and improve the space utilization. Disk arrays use different technologies, called RAID levels. different levels are used for different systems and applications to solve data security issues. To put it simply, RAID combines multiple hard disks into one logical sector. Therefore, the operating system only treats them as one hard disk.

Generally, high-performance disk arrays are achieved in the form of hardware, further combining disk access control and disk arrays on a controller (RAID controler) or controller card, different users need to meet the following four requirements:
(1) increase the access speed,
(2) fault tolerance (fault tolerance), security
(3) Effective Utilization of disks;
(4) balance the performance differences between CPU, memory, and disk as much as possible to improve the overall performance of the host.

Functions:

1. redundancy (fault tolerance)

2. Performance Improvement

RAID Category:
1. hardware RAID: The RAId interface card is used for implementation. The Kernel must support its driver, and the devices of this type are displayed as SCSI devices, codenamed as/dev/sd *
2. software RAID: implemented using the MD (multiple devices) module in the kernel. This type of device is represented as: md * under/etc *; in the current version of RH 5, the mdadm tool is used to manage soft RAID. (although raid can be simulated by software, the functions and performance of disk control are not as good as that of hardware, hardware raid is recommended in the production environment


Description of several common RAID types:

Figure:

Delete an array:

To completely clear the array:

 
 

  
  
[Root @ bogon ~] # Umount/dev/md0
  
  
Mdadm-Ss/dev/md0
  
  
[Root @ bogon ~] # Mdadm -- zero-superblock/dev/sd {B, c, d} 1
  
  
# -- When this option is added to zero-superblock, the system checks whether the array contains packets.