Cheat on increasing partitions and lvm
0.1 Increase kvm disk image size
This assumes that the vm is a kvm virtual machine with a qcow2 image type.
On the kvm host, issue this command to increase the size of the qcow2 image by
1 Gigabyte: sudo qemu-img resize /var/lib/libvirt/images/vm5.qcow2 +1G
Note that the size of the actual qcow2 file won't change at this point.
0.2 Boot the kvm vm
On booting you should see that the disk drive has increased in size by 1G
however, nothing has changed on the partitions. I used lsblk command.
root@vm5~[1007] $ lsblk NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT sda 8:0 0 9G 0 disk ├─sda1 8:1 0 1G 0 part /boot └─sda2 8:2 0 7G 0 part ├─cl-root 253:0 0 6.2G 0 lvm / └─cl-swap 253:1 0 820M 0 lvm [SWAP] sr0 11:0 1 1024M 0 rom root@vm5~[1008] $
In my example above, I have expanded the /dev/sda drive from 8G to 9G
Similarily, the command fdisk -l /dev/sda shows that you now have 9G of space
on the /dev/sda drive:
root@vm5~[1005] $ fdisk -l /dev/sda Disk /dev/sda: 9 GiB, 9663676416 bytes, 18874368 sectors Units: sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disklabel type: dos Disk identifier: 0xb23213cb Device Boot Start End Sectors Size Id Type /dev/sda1 * 2048 2099199 2097152 1G 83 Linux /dev/sda2 2099200 16777215 14678016 7G 8e Linux LVM root@vm5~[1006] $
0.3 Create a new primary partition using fdisk
The command to use is fdisk /dev/sda which manages the partition table on the
drive /dev/sda
root@vm5~[1008] $ fdisk /dev/sda Welcome to fdisk (util-linux 2.32.1). Changes will remain in memory only, until you decide to write them. Be careful before using the write command. Command (m for help): m Help: DOS (MBR) a toggle a bootable flag b edit nested BSD disklabel c toggle the dos compatibility flag Generic d delete a partition F list free unpartitioned space l list known partition types n add a new partition p print the partition table t change a partition type v verify the partition table i print information about a partition Misc m print this menu u change display/entry units x extra functionality (experts only) Script I load disk layout from sfdisk script file O dump disk layout to sfdisk script file Save & Exit w write table to disk and exit q quit without saving changes Create a new label g create a new empty GPT partition table G create a new empty SGI (IRIX) partition table o create a new empty DOS partition table s create a new empty Sun partition table
I then used the command n to create a new partition, and p to make it a
primary partition. The rest I just used the defaults as that used up
all the available space I had added.
Command (m for help): n
Partition type
p primary (2 primary, 0 extended, 2 free)
e extended (container for logical partitions)
Select (default p): p
Partition number (3,4, default 3):
First sector (16777216-18874367, default 16777216):
Last sector, +sectors or +size{K,M,G,T,P} (16777216-18874367, default 18874367):
Created a new partition 3 of type 'Linux' and of size 1 GiB.
Command (m for help):
I then saved and quit the fdisk session with the w command:
Command (m for help): w The partition table has been altered. Syncing disks.
Then I confirmed that I had a new partition from the 1G of added space using
the lsblk command again:
root@vm5~[1009] $ lsblk NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT sda 8:0 0 9G 0 disk ├─sda1 8:1 0 1G 0 part /boot ├─sda2 8:2 0 7G 0 part │ ├─cl-root 253:0 0 6.2G 0 lvm / │ └─cl-swap 253:1 0 820M 0 lvm [SWAP] └─sda3 8:3 0 1G 0 part sr0 11:0 1 1024M 0 rom root@vm5~[1010] $
You can see that my new partition is sda3.
You can also check what the partitions are with the fdisk -l command:
root@vm5~[1010] $ fdisk -l Disk /dev/sda: 9 GiB, 9663676416 bytes, 18874368 sectors Units: sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disklabel type: dos Disk identifier: 0xb23213cb Device Boot Start End Sectors Size Id Type /dev/sda1 * 2048 2099199 2097152 1G 83 Linux /dev/sda2 2099200 16777215 14678016 7G 8e Linux LVM /dev/sda3 16777216 18874367 2097152 1G 83 Linux Disk /dev/mapper/cl-root: 6.2 GiB, 6652166144 bytes, 12992512 sectors Units: sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk /dev/mapper/cl-swap: 820 MiB, 859832320 bytes, 1679360 sectors Units: sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes root@vm5~[1011] $
0.4 Change the Partition Type to be a LVM
The partition should be changed to a logical volume, so use fdisk again:
root@vm5~[1016] $ fdisk /dev/sda Welcome to fdisk (util-linux 2.32.1). Changes will remain in memory only, until you decide to write them. Be careful before using the write command. Command (m for help): p Disk /dev/sda: 9 GiB, 9663676416 bytes, 18874368 sectors Units: sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disklabel type: dos Disk identifier: 0xb23213cb Device Boot Start End Sectors Size Id Type /dev/sda1 * 2048 2099199 2097152 1G 83 Linux /dev/sda2 2099200 16777215 14678016 7G 8e Linux LVM /dev/sda3 16777216 18874367 2097152 1G 83 Linux Command (m for help): t Partition number (1-3, default 3): 3 Hex code (type L to list all codes): L 0 Empty 24 NEC DOS 81 Minix / old Lin bf Solaris 1 FAT12 27 Hidden NTFS Win 82 Linux swap / So c1 DRDOS/sec (FAT- 2 XENIX root 39 Plan 9 83 Linux c4 DRDOS/sec (FAT- 3 XENIX usr 3c PartitionMagic 84 OS/2 hidden or c6 DRDOS/sec (FAT- 4 FAT16 <32M 40 Venix 80286 85 Linux extended c7 Syrinx 5 Extended 41 PPC PReP Boot 86 NTFS volume set da Non-FS data 6 FAT16 42 SFS 87 NTFS volume set db CP/M / CTOS / . 7 HPFS/NTFS/exFAT 4d QNX4.x 88 Linux plaintext de Dell Utility 8 AIX 4e QNX4.x 2nd part 8e Linux LVM df BootIt 9 AIX bootable 4f QNX4.x 3rd part 93 Amoeba e1 DOS access a OS/2 Boot Manag 50 OnTrack DM 94 Amoeba BBT e3 DOS R/O b W95 FAT32 51 OnTrack DM6 Aux 9f BSD/OS e4 SpeedStor c W95 FAT32 (LBA) 52 CP/M a0 IBM Thinkpad hi ea Rufus alignment e W95 FAT16 (LBA) 53 OnTrack DM6 Aux a5 FreeBSD eb BeOS fs f W95 Ext'd (LBA) 54 OnTrackDM6 a6 OpenBSD ee GPT 10 OPUS 55 EZ-Drive a7 NeXTSTEP ef EFI (FAT-12/16/ 11 Hidden FAT12 56 Golden Bow a8 Darwin UFS f0 Linux/PA-RISC b 12 Compaq diagnost 5c Priam Edisk a9 NetBSD f1 SpeedStor 14 Hidden FAT16 <3 61 SpeedStor ab Darwin boot f4 SpeedStor 16 Hidden FAT16 63 GNU HURD or Sys af HFS / HFS+ f2 DOS secondary 17 Hidden HPFS/NTF 64 Novell Netware b7 BSDI fs fb VMware VMFS 18 AST SmartSleep 65 Novell Netware b8 BSDI swap fc VMware VMKCORE 1b Hidden W95 FAT3 70 DiskSecure Mult bb Boot Wizard hid fd Linux raid auto 1c Hidden W95 FAT3 75 PC/IX bc Acronis FAT32 L fe LANstep 1e Hidden W95 FAT1 80 Old Minix be Solaris boot ff BBT Hex code (type L to list all codes): 8e Changed type of partition 'Linux' to 'Linux LVM'. Command (m for help):
And just confirm that sda3 is now LVM by using p command to print the table:
Command (m for help): p Disk /dev/sda: 9 GiB, 9663676416 bytes, 18874368 sectors Units: sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disklabel type: dos Disk identifier: 0xb23213cb Device Boot Start End Sectors Size Id Type /dev/sda1 * 2048 2099199 2097152 1G 83 Linux /dev/sda2 2099200 16777215 14678016 7G 8e Linux LVM /dev/sda3 16777216 18874367 2097152 1G 8e Linux LVM Command (m for help): w The partition table has been altered. Syncing disks. root@vm5~[1017] $
Don't forget to w write the changes to disk:
0.5 run fsck on the new partition
This is the file system check, fsck command.
This will give you an error, as this partition does NOT yet have a filesystem
on it. i.e. You have not formatted that partition yet.
0.6 Add the new partition to the root logical volume, thus extending its size
At this stage I can format the new partition as another mount point, say
/data or something like that
1 Options to extend the partition (non disruptively)
1.1 Resizing using growpart (cloud-utils-growpart)
I had success on several kvm based VMs using the earlier approach in my org file here Resizing a guest disk space I recommend using this approach.
1.2 Blog (not attempted)
This blog shows how, if you are careful, you can extend the size of the partition without destroying the data on it, but I did NOT do this. Maybe next time. My biggest roadblock is that you would have to unmount the partition, and this is the root partition / that we are talking about, so I did not do this.