In order to go above that limit, there is the 'extended. When such partitions are created on a such derive, they are called 'primary'. The difference between 'primary' and 'logical' is imposed by the limits of the MBR partition scheme, where a drive can only contain 4 partitions. It's got two physical volumes and so fourth. For a clear definition of the terms - there is a good answer here. And I can do a VGS, volume group scan, and it can see that we found one volume group. If I try PV check on some other partition that it doesn't find as a physical volume it will tell you hey there's no LVM label on that partition. If I do PV check one of these it tells me yeah it's a logical volume thing and it found metadata. So we see here on this system it recognizes three partitions as physical volumes, and the first two are in a volume group called VG1, and we see the size and how much is free. So you can do help button command, like I could say help PVS, and it tells me about options for the PVS command. So we'll do LVM, and we get the LVM prompt and we type help and we get lots of stuff. So on this system I've set up some physical volumes and so fourth. So let's look at using LVM, some simple stuff. So instead of having to do a sudo pvcreate sudo vgdisplay you can do sudo LVM and then within the LVM prompt you can do multiple commands. So as to be expected these things are usually privileged commands. So there are stand alone commands like pvcreate and vgdisplay and so fourth, but the LVM command itself has similar commands inside and that can be a little more convenient, because it remembers some context where you are. There are lots of commands involved with LVM including a command called LVM. So the logical volume can grow and shrink as well as the volume group can grow and shrink. You can group those together into a volume group and then you can build from a volume group a piece that will be called a logical volume.
Where a physical volume is a disk or a disk partition. LVM we can really think of being three levels, so the abstraction of a logical volume is on top of volume groups and physical volumes.
So you get both flexibility and improved performance. You can collect together multiple disks or partitions and treat it as one thing, and it can grow and it can shrink and you also can strip across those physical disks or you can mirror so you got two copies. Logical volume manager or LVM provides a abstraction for viewing physical disks as one thing.
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