What is Logical Volume Manager (LVM)?

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LVM is a logical storage management tool. It allows one to take in storage devices (whole disks, LUNs, partitions, slices, divisions, etc.) as "Physical Volumes" (PVs) , allocate them to storage pools (Volume Groups - (VGs)). One then creates Logical Volumes (LVs) within the Volume Groups. These Logical Volumes are then used for data storage, e.g. for a filesystem, a database device, etc. One can then dynamically manage these Logical Volumes, e.g. relocate them among PVs, resize them, etc. - including while their data is in use (provided the use is consistent with any change in size of the LV).