File systems (such as / home or / usr, etc.) can be established on top of logical volumes. Logical Volume: Logical volumes of LVM are similar to hard disk partitions in non-LVM systems. An LVM volume group consists of one or more physical volumes. You can create one or more "LVM partitions" (logical volumes) on a volume group. Volume Group: An LVM volume group is similar to a physical hard disk in a non-LVM system and consists of physical volumes. Etc.) comparison, but contains management parameters related to LVM. It is the basic storage logical block of LVM, but it is the same as a basic physical storage medium (such as a partition or disk). Physical Volume: A physical volume refers to a hard disk partition or a device that has the same function as a disk partition (such as RAID). The physical media: This refers to the system's storage devices: hard disks, such as: / dev / hda, / dev / sda, etc., are the lowest-level storage unit of the storage system. The technology of logical volumes greatly improves the logic of disk management. The biggest feature of LVM is that it can dynamically manage disks, because the size of logical volumes can be dynamically adjusted without losing data. When we operate the underlying physical disk through software, it no longer directly operates the partition, but operates the underlying physical hard disk through logical volumes. In LVM, it encapsulates the underlying hard disk. In traditional disk management mechanisms, upper-layer applications directly access the file system to read and write to the underlying physical hard disk. LVM works by abstractly encapsulating the underlying physical hard disk and presenting it to the upper-layer application as a logical volume. With the emergence of LVM, the problem is solved, and users can easily adjust the size of the partition without downtime. When a partition runs out of space, the solution is usually to use symbolic links or tools to adjust the size of the partition (tools may cause our system to crash), but this does not fundamentally solve the problem. When a logical partition cannot store a file, the file cannot be stored across multiple partitions due to the limitation of the upper file system, so it cannot be placed in On multiple disks. The ordinary disk partition management method cannot change its size after the logical partition is divided.
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