Extending LVM using pvcreate, vgcreate, lvcreate, lvextend and resize2fs
components of LVM are as follows:
1. VG – Volume Group: high level container that holds one or more physical or logical volumes.
2. PV – Physical Volume: represents a storage device such as a disk drive or storage media.
3. PE – Physical Extent: each physical volume is divided into equal size blocks called physical extents.
4. LV – Logical Volume: eqivalent to a disk partition and can contain a filesystem.
5. LE – Logical Extent: Each logical volume (LV) is divided into equal size blocks called logical extents.
2. PV – Physical Volume: represents a storage device such as a disk drive or storage media.
3. PE – Physical Extent: each physical volume is divided into equal size blocks called physical extents.
4. LV – Logical Volume: eqivalent to a disk partition and can contain a filesystem.
5. LE – Logical Extent: Each logical volume (LV) is divided into equal size blocks called logical extents.
Creating new partition
First you need to add a new disk, it does not matter whether it is a
virtual or physical. In my case I have added a Disk /dev/vdb.
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[root@mytestbox ~]# cat /etc/redhat-release
Red Hat Enterprise Linux Server release 6.3 (Santiago)
[root@mytestbox ~]# fdisk -l
Disk /dev/vda: 21.5 GB, 21474836480 bytes16 heads, 63 sectors/track, 41610 cylindersUnits = cylinders of 1008 * 512 = 516096 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk identifier: 0x0007c501 Device Boot Start End Blocks Id System/dev/vda1 * 3 409 204800 83 LinuxPartition 1 does not end on cylinder boundary./dev/vda2 409 41611 20765696 8e Linux LVMPartition 2 does not end on cylinder boundary.Disk /dev/mapper/vg_01-swap_vol: 8589 MB, 8589934592 bytes255 heads, 63 sectors/track, 1044 cylindersUnits = cylinders of 16065 * 512 = 8225280 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk identifier: 0x00000000<p>Disk /dev/mapper/vg_01-root_vol: 12.7 GB, 12650020864 bytes255 heads, 63 sectors/track, 1537 cylindersUnits = cylinders of 16065 * 512 = 8225280 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk identifier: 0x00000000<p>Disk /dev/vdb: 21.5 GB, 21474836480 bytes16 heads, 63 sectors/track, 41610 cylindersUnits = cylinders of 1008 * 512 = 516096 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk identifier: 0x00000000 |
Next you need to create a partition on this new disk. For that we will use fdisk
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[root@mytestbox ~]# fdisk /dev/vdb
Device contains neither a valid DOS partition table, nor Sun, SGI or OSF disklabelBuilding a new DOS disklabel with disk identifier 0x3467714a.Changes will remain in memory only, until you decide to write them.After that, of course, the previous content won't be recoverable.Warning: invalid flag 0x0000 of partition table 4 will be corrected by w(rite)WARNING: DOS-compatible mode is deprecated. It's strongly recommended to switch off the mode (command 'c') and change display units to sectors (command 'u').Command (m for help): pDisk /dev/vdb: 21.5 GB, 21474836480 bytes16 heads, 63 sectors/track, 41610 cylindersUnits = cylinders of 1008 * 512 = 516096 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk identifier: 0x3467714aDevice Boot Start End Blocks Id System |
We will create a new primary partition
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Command (m for help): n
Command action<br /> e extended<br /> p primary partition (1-4)pPartition number (1-4): 1First cylinder (1-41610, default 1):press enterUsing default value 1Last cylinder, +cylinders or +size{K,M,G} (1-41610, default 41610):press enterUsing default value 41610Command (m for help): tSelected partition 1Hex code (type L to list codes): 8eChanged system type of partition 1 to 8e (Linux LVM)Command (m for help): wThe partition table has been altered!Calling ioctl() to re-read partition table.Syncing disks. |
And check with fdisk if it has been recognized
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[root@mytestbox ~]# fdisk -l
Disk /dev/vda: 21.5 GB, 21474836480 bytes16 heads, 63 sectors/track, 41610 cylindersUnits = cylinders of 1008 * 512 = 516096 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk identifier: 0x0007c501Device Boot Start End Blocks Id System/dev/vda1 * 3 409 204800 83 LinuxPartition 1 does not end on cylinder boundary./dev/vda2 409 41611 20765696 8e Linux LVMPartition 2 does not end on cylinder boundary.Disk /dev/vdb: 21.5 GB, 21474836480 bytes16 heads, 63 sectors/track, 41610 cylindersUnits = cylinders of 1008 * 512 = 516096 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk identifier: 0x3467714aDevice Boot Start End Blocks Id System/dev/vdb1 1 41610 20971408+ 8e Linux LVM[root@mytestbox ~]# |
Creating physical volume
First let’s check the size of existing physical volume
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| <br />[root@mytestbox ~]# pvs PV VG Fmt Attr PSize PFree /dev/vda2 vg_01 lvm2 a-- 19.78g 0 |
And create a new physical volume and check if it worked
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[root@mytestbox ~]# pvcreate /dev/vdb1
Writing physical volume data to disk "/dev/vdb1" Physical volume "/dev/vdb1" successfully created[root@mytestbox ~]# pvs PV VG Fmt Attr PSize PFree /dev/vda2 vg_01 lvm2 a-- 19.78g 0 /dev/vdb1 lvm2 a-- 20.00g 20.00g[root@mytestbox ~]# pvdisplay --- Physical volume --- PV Name /dev/vda2 VG Name vg_01 PV Size 19.80 GiB / not usable 23.00 MiB Allocatable yes (but full) PE Size 32.00 MiB Total PE 633 Free PE 0 Allocated PE 633 PV UUID vp2QRP-Ufi4-2f3v-afSI-o4pM-2hYb-H4YRoh "/dev/vdb1" is a new physical volume of "20.00 GiB" --- NEW Physical volume --- PV Name /dev/vdb VG Name<br /> PV Size 20.00 GiB Allocatable NO PE Size 0 Total PE 0 Free PE 0 Allocated PE 0 PV UUID 7X10kE-GF36-iuhE-1ja6-9LLa-q2CI-hWRiao[root@mytestbox ~]# |
Extending volume group
Now it’s time to extend our volume group, Please note the values Free PE / Size before and after the extend.
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[root@mytestbox ~]# vgdisplay
--- Volume group --- VG Name vg_01 System ID Format lvm2 Metadata Areas 1 Metadata Sequence No 3 VG Access read/write VG Status resizable MAX LV 0 Cur LV 2 Open LV 2 Max PV 0 Cur PV 1 Act PV 1 VG Size 19.78 GiB PE Size 32.00 MiB Total PE 633 Alloc PE / Size 633 / 19.78 GiB Free PE / Size 0 / 0 VG UUID qHhhfc-HvnQ-bS2t-dUqX-buOP-MWCf-THdQQP[root@mytestbox ~]# vgextend vg_01 /dev/vdb1 Volume group "vg_01" successfully extended[root@mytestbox ~]# vgdisplay --- Volume group --- VG Name vg_01 System ID Format lvm2 Metadata Areas 2 Metadata Sequence No 4 VG Access read/write VG Status resizable MAX LV 0 Cur LV 2 Open LV 2 Max PV 0 Cur PV 2 Act PV 2 VG Size 39.75 GiB PE Size 32.00 MiB Total PE 1272 Alloc PE / Size 633 / 19.78 GiB Free PE / Size 639 / 19.97 GiB VG UUID qHhhfc-HvnQ-bS2t-dUqX-buOP-MWCf-THdQQP[root@mytestbox ~]# |
Extending logical volume
Now, as we got a volume group extended, we can extend a desired logical volume. In my case it will be a root partition.
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[root@mytestbox ~]# lvextend -L +19G /dev/vg_01/root_vol (e.g, /dev/mapper/VolGroup00-LogVo100)
Extending logical volume root_vol to 30.78 GiB Logical volume root_vol successfully resized |
And resize file system so now size can now be visible to the system
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root@mytestbox ~]# df -h
Filesystem Size Used Avail Use% Mounted on/dev/mapper/vg_01-root_vol 12G 1.3G 9.8G 12% tmpfs 246M 0 246M 0% /dev/shm/dev/vda1 194M 78M 106M 43% /boot[root@mytestbox ~]# resize2fs /dev/vg_01/root_volresize2fs 1.41.12 (17-May-2010Filesystem at /dev/vg_01/root_vol is mounted on /; on-line resizing requiredold desc_blocks = 1, new_desc_blocks = 2Performing an on-line resize of /dev/vg_01/root_vol to 8069120 (4k) blocks.The filesystem on /dev/vg_01/root_vol is now 8069120 blocks long.[root@mytestbox ~]# df -hFilesystem Size Used Avail Use% Mounted on/dev/mapper/vg_01-root_vol 31G 1.3G 28G 5% /tmpfs 246M 0 246M 0% /dev/shm/dev/vda1 194M 78M 106M 43% /boot[root@mytestbox ~]# |
