1 00:00:00,000 --> 00:00:11,480 In this lesson, you will learn about Logical Volume Manager. In this video, I'll tell you 2 00:00:11,480 --> 00:00:18,040 about the different components that you are using in LVM. In the heart of LVM is a volume 3 00:00:18,040 --> 00:00:24,719 group. And this volume group is an abstraction of all the storage that you want to put in 4 00:00:24,719 --> 00:00:31,320 your LVM configuration. You do that by using the so-called PV, the physical volumes. And 5 00:00:31,320 --> 00:00:36,520 these physical volumes can be hard disks, it can be partitions, it can be any valid 6 00:00:36,520 --> 00:00:42,000 block device. And that is allowing you for flexibility. If you run out of disk space 7 00:00:42,000 --> 00:00:49,799 or your volume group, you can easily add more storage by adding PVs. Now from the volume 8 00:00:49,799 --> 00:00:56,680 group, you are going to create your logical volumes. And these are the storage devices 9 00:00:56,680 --> 00:01:04,599 on which you are going to use your file systems. So your MKFS is happening here. And the nice 10 00:01:04,599 --> 00:01:10,320 thing is that these logical volumes get their disk space from the volume group, but they 11 00:01:10,320 --> 00:01:14,480 are not aware and there is no strict relation. And that means that if your logical volume 12 00:01:14,480 --> 00:01:19,839 runs out of disk space, you just go get more disk space from the volume group. And if in 13 00:01:19,839 --> 00:01:24,239 the volume group, there is no additional disk space available, well, you are just going 14 00:01:24,239 --> 00:01:30,559 to add another storage device right here as a PV. And that is what implements the flexibility 15 00:01:30,559 --> 00:01:37,559 in an LVM environment. So let's summarize the procedure for creating LVM. First, you 16 00:01:37,559 --> 00:01:42,440 need to create a partition. And this partition needs to be set to the appropriate type, which 17 00:01:42,440 --> 00:01:50,639 is 8E on MBR, 8E00 on GPT. Or when you use modern utilities, you can use LVM, which is 18 00:01:50,639 --> 00:01:57,800 an alias to the correct partition type. Then you use PVCreate on your device to mark the 19 00:01:57,800 --> 00:02:04,440 partition as a physical volume. And next, VGCreate, you give the volume group a name 20 00:02:04,440 --> 00:02:09,880 and you add a physical volume into it, devNNN. That corresponds to the partition that you 21 00:02:09,960 --> 00:02:15,399 have just created as an LVM type partition. Oh, and by the way, if you are wondering, 22 00:02:15,399 --> 00:02:21,240 do we need to create a partition? No, you can also put an entire disk in LVM, but it's nicer 23 00:02:21,240 --> 00:02:26,600 for administration purposes to do partitions because they are clearly marked as an LVM 24 00:02:26,600 --> 00:02:33,479 partition type. Once you have your volume group, you can create logical volume from it. So LVCreate 25 00:02:33,479 --> 00:02:40,839 minus uppercase L1G will create a one gigabyte volume. Minus N, LVName will use the name 26 00:02:40,839 --> 00:02:46,199 LVName, and VGName will put it in the volume group that you have created. And that will create 27 00:02:46,199 --> 00:02:54,440 a one gigabyte volume in that group. And then you can use PVS, VGS, LVS, or PVDisplay, VGDisplay, 28 00:02:54,440 --> 00:02:59,880 LVDisplay to verify. The display commands are giving a little bit more information. 29 00:02:59,880 --> 00:03:06,039 The PVS and so on commands are giving a short list. And once you are done, you can mount it 30 00:03:06,039 --> 00:03:12,039 using dev VGName LVName, or using the device mapper name that is used behind it, which is 31 00:03:12,039 --> 00:03:19,080 slash dev slash mapper slash VGName dash LVName. Let me show you how to set up a simple LVM 32 00:03:19,080 --> 00:03:25,800 environment. So I'm going to start with the LSB OK, because in order to set up LVM, we need a 33 00:03:25,800 --> 00:03:33,080 block device. And I need to analyze and determine what I've got. Well, I'm going to use dev NVMe 34 00:03:33,080 --> 00:03:39,720 0N2, on which we have sufficient space available. So I'm going for my favorite utility, and that is 35 00:03:39,720 --> 00:03:48,119 fdisk on dev NVMe 0N2. And there, you can ignore the message that you see here. This is just to 36 00:03:48,119 --> 00:03:52,279 scare people away that don't know what they're doing. But you know what you're doing, right? 37 00:03:52,279 --> 00:03:58,039 So I'm going to use N for a new partition. The new partition will be partition number four. 38 00:03:58,039 --> 00:04:03,479 And first sector, well, I'm not even going to think about it. I'm just accepting the default. 39 00:04:03,479 --> 00:04:10,759 And last sector, let's make this a four gigabyte partition, plus 4G. There we can see that the new 40 00:04:10,759 --> 00:04:16,600 partition is created of the type Linux file system. Well, that is what I need to change. So I'm using 41 00:04:16,600 --> 00:04:23,640 T to change the partition type. And for partition number four, I'm setting the partition type to 42 00:04:23,640 --> 00:04:30,279 LVM. And now, I'm using P to verify that partition four was correctly set as LVM. 43 00:04:30,279 --> 00:04:37,720 It is, so I can use W to write and exit. As always, it's a good idea to verify your storage 44 00:04:37,720 --> 00:04:45,799 using LSBLK. And there, we can see that we have an NVMe 0N2 P4 partition. That's the one that I just 45 00:04:45,799 --> 00:04:55,959 created. So I'm going to use PV create on dev, NVMe 0N2 P4, which will mark it as a physical 46 00:04:55,959 --> 00:05:04,440 volume. That will make it usable by LVM. Next, I can use VG create. I'm calling it VG data. 47 00:05:04,440 --> 00:05:13,399 And I'm putting in my device, NVMe 0N2 P4. And that is telling me that the volume group 48 00:05:13,399 --> 00:05:22,279 was successfully created. Well, that was easy. Now, LV create minus L1G. I want a one gigabyte 49 00:05:22,279 --> 00:05:31,160 logical volume minus NLV data. And I need to do that in VG data. And as you can see, the logical 50 00:05:31,160 --> 00:05:39,320 volume LV data was created. Good. Now, I can use LVS. And there, we can see that LV data is indeed 51 00:05:39,320 --> 00:05:48,359 correctly created with a size of one gigabyte. Now, the fun fact is that the logical volume has 52 00:05:48,359 --> 00:05:58,200 two different names. When I use LS minus L on dev VG data LV data, I can see that that is one name 53 00:05:58,200 --> 00:06:04,200 pointing to a device DM2. That's a symbolic link to the device mapper device. Device mapper is 54 00:06:04,200 --> 00:06:09,799 a system that is used behind LVM. And here, we can see the name of that device. And when I use 55 00:06:09,799 --> 00:06:17,239 LS minus L on dev mapper, you can see that right in there, we have VG data LV data pointing to 56 00:06:17,239 --> 00:06:24,119 the same device. And it doesn't matter at all which one of these names you are using. Now, let's verify 57 00:06:24,119 --> 00:06:30,359 LVS is showing all my logical volumes. VGS is showing all my volume groups. We should be good 58 00:06:30,359 --> 00:06:33,720 here. We just created the LVM logical volume.