What is lvm partition ubuntu

Physical Volumes correspond to disks; they are block devices that provide the space to store logical volumes. Logical volumes correspond to partitions: they hold a filesystem. Unlike partitions though, logical volumes get names rather than numbers, they can span across multiple disks, and do not have to be physically contiguous.

The Specifics One of the biggest advantages LVM has is that most operations can be done on the fly, while the system is running. Most operations that you can do with gparted require that the partitions you are trying to manipulate are not in use at the time, so you have to boot from the livecd to perform them.

You also often run into the limits of the msdos partition table format with gparted, including only 4 primary partitions, and all logical partitions must be contained within one contiguous extended partition.

Resizing Partitions With gparted you can expand and shrink partitions, but only if they are not in use. When expanding a partition, gparted can only expand it into adjacent free space, but LVM can use free space anywhere in the Volume Group , even on another disk. When using gparted, this restriction often means that you must move other partitions around to make space to expand one, which is a very time consuming process that can result in massive data loss if it fails or is interrupted power loss.

Moving Partitions Moving partitions with gparted is usually only necessary in the first place because of the requirement that partitions be physically contiguous, so you probably won't ever need to do this with LVM.

If you do, unlike gparted, LVM can move a partition while it is in use, and will not corrupt your data if it is interrupted. In the event that your system crashes or loses power during the move, you can simply restart it after rebooting and it will finish normally.

When I got my SSD drive, I simply plugged it in, booted it up, and asked lvm to move my running root filesystem to the new drive in the background while I continued working. Another reason you might want to move is to replace an old disk with a new, larger one. You can migrate the system to the new disk while using it, and then remove the old one later. Many Partitions If you like to test various Linux distributions, or just different version of Ubuntu, or both, you can quickly end up with quite a few partitions.

With conventional msdos partitions, this becomes problematic due to its limitations. We can format the LVM partition using the ext4 file-system with the following command:. One of the benefits of LVM is to extend or reduce the size of the partitions. We can resize the logical volumes on the fly without rebooting the server. In some situations, we need to expand the size of a low space partition.

We can easily expand any partition using the lvextend command. We can extend logical volumes only if the volume group has enough free space. Reducing logical volume is a more interesting part than any other part in logical volume management.

Before reducing logical volume, it is good to back up the data. I have tried to explain each topic briefly. As you can see above, you'll be prompted to enter the first sector and the last sector to use for the partition.

If you're using the whole disk for LVM as we are , just hit return to accept the default first, then hit return again to accept the default last sector. Assuming you've already prepared your disk or partition for lvm as described above, before adding it to a volume group's pool, the physical disk or partition must be "initialised" to create a physical volume that is recognised by lvm.

In order to initialise a disk or partition for use with lvm, you need to use the pvcreate command. To initialise a partition as physical volume, just use the partitions device name. In order to add a physical volume to a volume group's pool of physical space, you need to use the vgextend command. Here's a screenshot of the ubuntu volume group's info before we do that:. The same principles apply when extending any logical volume.

After the logical volume has been extended, you must also extend the size of the underlying filesystem which in our case is ext4. As you'll see shortly, we can do all of this as part of the same command. To extend a logical volume, you can use either the lvextend command or the lvresize command.

The lvextend command is considered a safer option because it won't allow you to reduce the size of the logical volume should you make a mistake when entering the command. We can use the --resizefs option to automatically resize the underlying filesystem. Purly for illustration purposes, we'll extend our Let's extend it by a further extents which will extend it from If you'd rather extend by a specific size specified in Megabytes, Gigabytes, Terabytes, Petabytes, or Exabytes, you could use M,G,T,P, or E respectively or the relevant letter in lower case.

Also note that if you wish to use physical extents from a particular physical volume to fulfil the request i. For illustration purposes, the screenshot below shows how things look now for us given that we didn't specify we wanted all physical extents from same physical volume. If you're curious, take a look at the volumes under "Physical View" and Logical Views" in the system-config-lvm tool to see exactly how things look visually.

When you create a new logical volume, you create it in a volume group. That volume group must have sufficient free space physical extents to create your logical volume. Note that when choosing the name of your logical volume, it is best not to use a "-" i.

Lets create an ext4 filesystem on our new logical volume using the mkfs. Notice in the above screenshot that the text to the right says "Mount point when rebooted: None". Michael Kubler Michael Kubler 4 4 silver badges 2 2 bronze badges. Abhinav Abhinav 1 1 silver badge 3 3 bronze badges. Yes it's just a personal server, so it sounds like I won't be needing it.

Late, but still. So yes, if you have a situation when you have installer on more than one partition, you should have a look att LVM. It isn't that hard to understand actually. Volume group are same has a hard disk. Logical volume are the same as a partition and Physical volumes are the partitions that you build the Volume group on. LVM adds a lot of complexity. I left it enabled by default on my small server and now have a confusing situation with all these logical volumes not being set up the way I want, and now I have to go research how to fix this Bananeweizen Bananeweizen 2 2 gold badges 14 14 silver badges 20 20 bronze badges.

Really self-defeating and destructive logic. People need to learn what's possible so they can decide what they need. TomDworzanski Actually, this post has merit. There is a principal called "the last responsible moment". There is far too much information in this world to focus carefully on most choices.

If you have never had a problem that LVM solves - then it makes sense to ignore it until you do. Sometimes you need to survey what's out there which is what OP is clearly doing. There was probably a time you did the same. Besides, we're not talking about all the information in the world With Ubuntu, it's enabled by default. I didn't know what it was and left it enabled. I wish I could go back.