Linux: LVM-An Introduction
Have you ever wondered while your linux installation that how much space should you reserve for the system and user files ? That’s a question that troubles many of us “How should i partition my disk drive ? ” Although you would get many suggestions on that but why to think about it if you have a better alternative…..LVM
According to Wikipedia , logical volume management or LVM provides a method of allocating space on mass-storage devices that is more flexible than conventional partitioning schemes. In particular, a volume manager can concatenate, stripe together or otherwise combine partitions into larger virtual ones that administrators can re-size or move, potentially without interrupting system use.
Let’s understand it with an example
Say Samuel has the following partitions on his disk
Now Samuel installed a bunch of softwares and is left with no space on root for further installation of softwares.He has the following alternatives for resizing :
If the same condition arises in lvm you don’t need to follow the long lengthy steps . Resizing is just a few commands away that too when you are working on the system disk drive whose partitioning you want to configure.That’s where LVM comes in place. Other advantages include:

According to Wikipedia , logical volume management or LVM provides a method of allocating space on mass-storage devices that is more flexible than conventional partitioning schemes. In particular, a volume manager can concatenate, stripe together or otherwise combine partitions into larger virtual ones that administrators can re-size or move, potentially without interrupting system use.
Let’s understand it with an example
Say Samuel has the following partitions on his disk
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| /boot /dev/sda1 512 Megabytes swap /dev/sda2 256 Megabytes / /dev/sda3 10 Gigabytes /home /dev/sda4 30 Gigabytes |
Now Samuel installed a bunch of softwares and is left with no space on root for further installation of softwares.He has the following alternatives for resizing :
- Reformat the disk, change the partitioning scheme and reinstall.
- Buy a new disk and figure out some new partitioning scheme that will require the minimum of data movement.
- Set up a symlink farm on / pointing to /home and install the new software on /home
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| /boot /dev/hda1 512 Megabytes swap /dev/vg/swap 256 Megabytes / /dev/vg/root 10 Gigabytes /home /dev/vg/home 30 Gigabytes |
- Have logical volumes stretched over several disks.
- Create small logical volumes and resize them “dynamically” as they get filled up.
- Resize logical volumes regardless of their order on disk. It does not depend on the position of the LV within VG, there is no need to ensure surrounding available space.
- Resize/create/delete logical and physical volumes online. File systems on them still need to be resized, but some (such as ext4) support online resizing.
- Snapshots allow you to backup a frozen copy of the file system, while keeping service downtime to a minimum.

- They start with physical volumes (PVs), which can be either hard disks, hard disk partitions. Volume management treats each PV as being composed of a sequence of chunks called physical extents (PEs).
- Logical volume groups are created by combining PVs.
- As each PV consists of a number of fixed-size physical extents (PEs), similarly, each LV consists of a number of fixed-size logical extents (LEs)
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