Introduction to LinuxRAID

Introduction to LinuxRAID
Raid
RAID Level: it only indicates that the disk organization mode is different and there is no context:
0: Strip
Advantage: Performance Improvement: Read and Write
Insufficient: no redundancy (fault tolerance) Capability
Space Utilization: nS
At least two disks are required.
1: Image
Performance: lower Write Performance and improved read performance
Redundancy: available
Space Utilization: 1/2
At least two disks are required.
2
3
4: Verification Code
5: Take turns as the verification Disk
Performance: read/write performance is improved
Redundancy: available
Space Utilization: (n-1)/n * nS
At least 3
6
0, 1, 5 is used more
0 + 1: Strip first, then mirror
Performance: improved reading and writing
Redundancy: available
Space Utilization: 1/2
At least 4
1 + 0: first mirror, then strip
Performance: improved reading and writing
Redundancy: available
Space Utilization: 1/2
At least 4
5 + 0:
Performance: improved reading and writing
Redundancy: available
Space Utilization: (n-2)/n
At least 6

Jbod: combines multiple small disks into one dashboard.
Performance: None
Redundancy: None
Space Utilization: 100%
At least 2

Logical RAID:
/Dev/md #
/Dev/md1
/Dev/md2
/Dev/md3


Md:
Mdadm: RAID any block Device
Modeled commands:
Creation Mode:
-C
Special options:
-L: Level
-N: number of devices
-A {yes | no}: whether to automatically create a device file for it
-C: CHUNK size. The default value is 64 KB.

Management Mode:
-- Add, -- remove
Mdadm/dev/md # -- fail/dev/sda7: the simulation is corrupted.
Monitoring Mode:
-F
Growth Mode:
-G
Assembly mode:
-

Stop the array:
Mdadm-S/dev/md1

Mdadm-D | -- detail/dev/md #: View Details of array #

Save the current RAID information to the configuration file for later Assembly:
Mdadm-D -- scan>/etc/mdadm. conf


Watch: periodically executes a command and displays the result in full screen mode.
-N #: Specify the cycle length # seconds. The default value is 2 seconds.
Syntax: watch-n # 'command'

MD: Multi Device
DM: Device Mapper
Logical Device
RAID, LVM2