Volume Groups and Logical Volumes

Volume groups and logical volumes allows more creative and flexible partitioning schemas to be created than conventional partitioning schemas we have already discussed.

A volume group allows us to gather disks, physical and logical partitions into a single logical pool of storage. This pool of storage can then be partitioned (like a disk) by using a logical volume.

Only disks that have the type lvm, and physical partitions or logical partitions that have filesystem types lvm2 can be grouped together in a volume group.

Note

Once a physical or logical partition is grouped together into a volume group, they cannot be declared in another volume group.

In this example, an extended physical partition that has two logical partitions that have lvm filesystems; and a disk of type lvm are pooled together via a volume group grp1. A logical volume is used to partition further this volume group.

{
        "partitioning": {
            "disks": [
              {
                "name": "sda",
                "type": "msdos",
                "size": 20480,
                "partitions": [
                  {
                    "number": 1,
                    "fstype": "ext3",
                    "mountPoint": "/boot",
                    "size": 1024
                  },
                  {
                    "number": 2,
                    "fstype": "linux-swap",
                    "size": 1024
                  },
                  {
                    "number": 3,
                    "fstype": "extended",
                    "size": 18432,
                    "partitions": [
                      {
                        "number": 5,
                        "fstype": "lvm2",
                        "size": 9216
                      },
                      {
                        "number": 6,
                        "fstype": "lvm2",
                        "size": 9216
                      }
                    ]
                  }
                ]
              },
              {
                "name": "sdb",
                "type": "lvm",
                "size": 122880
              }
            ],
            "volumeGroups": [
              {
                "name": "grp1",
                "physicalVolumes": [
                  {
                    "name": "sda5"
                  },
                  {
                    "name": "sda6"
                  },
                  {
                    "name": "sdb"
                  }
                ]
              }
            ],
            "logicalVolumes": [
              {
                "name": "vol1",
                "vg_name": "grp1",
                "fstype": "ext3",
                "mountPoint": "/home",
                "size": 4098
              },
              {
                "name": "vol2",
                "vg_name": "grp1",
                "fstype": "ext3",
                "mountPoint": "/space",
                "size": 64,
                "grow": true
              }
            ]
        }
}