Linux Training : l. LVM


  • Logical Volume Management aggregates drives

    LVM is a way to manage storage space so the filesystem can grow as needed. In general, once the filesystem is established and all drives mounted, making changes is very difficult if a partition runs out of room. If /var fills up, the system halts (
    Unknown macro: {tm}


    ). With LVM, the filesystem can be expanded without having to copy all the data to a larger drive. For the most part here, LVM is used during the initial installation and rarely is it used afterwards.
    • Physical groups
      Physical groups are the actual drive partitions themselves.
        PV /dev/sda2   VG VolGroup70   lvm2 [148.94 GB / 0    free]
        Total: 1 [148.94 GB] / in use: 1 [148.94 GB] / in no VG: 0 [0   ]
      This shows a single physical volume group that uses sda2 partition and it all allocated to VolGroup70
    • Volume groups
      These are the structures on top of the physical groups. They are used to form the bases for the filesystem mount point.
        Reading all physical volumes.  This may take a while...
        Found volume group "VolGroup70" using metadata type lvm2
    • Logical volumes
      These are partitions created from the Volume groups.
        ACTIVE            '/dev/VolGroup70/LvRoot' [143.94 GB] inherit
        ACTIVE            '/dev/VolGroup70/LvLogs' [4.00 GB] inherit
        ACTIVE            '/dev/VolGroup70/LvSwap' [1.00 GB] inherit
      These logical partition match what mount says is mounted (swap is not "mounted" it is simply used)
      /dev/mapper/VolGroup70-LvRoot on / type ext3 (rw)
      proc on /proc type proc (rw)
      sysfs on /sys type sysfs (rw)
      devpts on /dev/pts type devpts (rw,gid=5,mode=620)
      /dev/mapper/VolGroup70-LvLogs on /var/log type ext3 (rw)
      /dev/sda1 on /boot type ext3 (rw)
      tmpfs on /dev/shm type tmpfs (rw)
      none on /proc/sys/fs/binfmt_misc type binfmt_misc (rw)