Resize an OS disk that has a GPT partition

  • 12 minutes to read

Applies to: ✔️ Linux VMs ✔️ Flexible scale sets

Note

This article applies only to OS disks that have a GUID Partition Table (GPT) partition.

This article describes how to increase the size of an OS disk that has a GPT partition in Linux.

Identify whether the OS disk has an MBR or GPT partition

Use the parted command to identify if the disk partition has been created with either a master boot record (MBR) partition or a GPT partition.

MBR partition

In the following output, Partition Table shows a value of msdos. This value identifies an MBR partition.

            [user@myvm ~]# parted -l /dev/sda Model: Msft Virtual Disk (scsi) Disk /dev/sda: 107GB Sector size (logical/physical): 512B/512B Partition Table: msdos Number  Start   End     Size    Type     File system  Flags 1       1049kB  525MB   524MB   primary  ext4         boot 2       525MB   34.4GB  33.8GB  primary  ext4 [user@myvm ~]#

GPT partition

In the following output, Partition Table shows a value of gpt. This value identifies a GPT partition.

            [user@myvm ~]# parted -l /dev/sda Model: Msft Virtual Disk (scsi) Disk /dev/sda: 68.7GB Sector size (logical/physical): 512B/512B Partition Table: gpt Disk Flags:  Number  Start   End     Size    File system  Name                  Flags 1       1049kB  525MB   524MB   fat16        EFI System Partition  boot 2       525MB   1050MB  524MB   xfs 3       1050MB  1052MB  2097kB                                     bios_grub 4       1052MB  68.7GB  67.7GB                                     lvm

If your virtual machine (VM) has a GPT partition on your OS disk, increase the size of the OS disk.

Increase the size of the OS disk

The following instructions apply to Linux-endorsed distributions.

Note

Before you proceed, make a backup copy of your VM, or take a snapshot of your OS disk.

Ubuntu

To increase the size of the OS disk in Ubuntu 16.x and 18.x:

  1. Stop the VM.
  2. Increase the size of the OS disk from the portal.
  3. Restart the VM, and then sign in to the VM as a root user.
  4. Verify that the OS disk now displays an increased file system size.

In the following example, the OS disk has been resized from the portal to 100 GB. The /dev/sda1 file system mounted on / now displays 97 GB.

            user@myvm:~# df -Th Filesystem     Type      Size  Used Avail Use% Mounted on udev           devtmpfs  314M     0  314M   0% /dev tmpfs          tmpfs      65M  2.3M   63M   4% /run /dev/sda1      ext4       97G  1.8G   95G   2% / tmpfs          tmpfs     324M     0  324M   0% /dev/shm tmpfs          tmpfs     5.0M     0  5.0M   0% /run/lock tmpfs          tmpfs     324M     0  324M   0% /sys/fs/cgroup /dev/sda15     vfat      105M  3.6M  101M   4% /boot/efi /dev/sdb1      ext4       20G   44M   19G   1% /mnt tmpfs          tmpfs      65M     0   65M   0% /run/user/1000 user@myvm:~#

SUSE

To increase the size of the OS disk in SUSE 12 SP4, SUSE SLES 12 for SAP, SUSE SLES 15, and SUSE SLES 15 for SAP:

  1. Stop the VM.
  2. Increase the size of the OS disk from the portal.
  3. Restart the VM.

When the VM has restarted, complete these steps:

  1. Access your VM as a root user by using this command:

                    # sudo -i

  2. Use the following command to install the growpart package, which you'll use to resize the partition:

                    # zypper install growpart

  3. Use the lsblk command to find the partition mounted on the root of the file system (/). In this case, we see that partition 4 of device sda is mounted on /:

                    # lsblk NAME   MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT sda      8:0    0   48G  0 disk ├─sda1   8:1    0    2M  0 part ├─sda2   8:2    0  512M  0 part /boot/efi ├─sda3   8:3    0    1G  0 part /boot └─sda4   8:4    0 28.5G  0 part / sdb      8:16   0    4G  0 disk └─sdb1   8:17   0    4G  0 part /mnt/resource

  4. Resize the required partition by using the growpart command and the partition number determined in the preceding step:

                    # growpart /dev/sda 4 CHANGED: partition=4 start=3151872 old: size=59762655 end=62914527 new: size=97511391 end=100663263

  5. Run the lsblk command again to check whether the partition has been increased.

    The following output shows that the /dev/sda4 partition has been resized to 46.5 GB:

                    linux:~ # lsblk NAME   MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT sda      8:0    0   48G  0 disk ├─sda1   8:1    0    2M  0 part ├─sda2   8:2    0  512M  0 part /boot/efi ├─sda3   8:3    0    1G  0 part /boot └─sda4   8:4    0 46.5G  0 part / sdb      8:16   0    4G  0 disk └─sdb1   8:17   0    4G  0 part /mnt/resource

  6. Identify the type of file system on the OS disk by using the lsblk command with the -f flag:

                    linux:~ # lsblk -f NAME   FSTYPE LABEL UUID                                 MOUNTPOINT sda ├─sda1 ├─sda2 vfat   EFI   AC67-D22D                            /boot/efi ├─sda3 xfs    BOOT  5731a128-db36-4899-b3d2-eb5ae8126188 /boot └─sda4 xfs    ROOT  70f83359-c7f2-4409-bba5-37b07534af96 / sdb └─sdb1 ext4         8c4ca904-cd93-4939-b240-fb45401e2ec6 /mnt/resource

  7. Based on the file system type, use the appropriate commands to resize the file system.

    For xfs, use this command:

                    #xfs_growfs /

    Example output:

                    linux:~ # xfs_growfs / meta-data=/dev/sda4              isize=512    agcount=4, agsize=1867583 blks          =                       sectsz=512   attr=2, projid32bit=1          =                       crc=1        finobt=0 spinodes=0 rmapbt=0          =                       reflink=0 data     =                       bsize=4096   blocks=7470331, imaxpct=25          =                       sunit=0      swidth=0 blks naming   =version 2              bsize=4096   ascii-ci=0 ftype=1 log      =internal               bsize=4096   blocks=3647, version=2          =                       sectsz=512   sunit=0 blks, lazy-count=1 realtime =none                   extsz=4096   blocks=0, rtextents=0 data blocks changed from 7470331 to 12188923

    For ext4, use this command:

                    #resize2fs /dev/sda4

  8. Verify the increased file system size for df -Th by using this command:

                    #df -Thl

    Example output:

                    linux:~ # df -Thl Filesystem     Type      Size  Used Avail Use% Mounted on devtmpfs       devtmpfs  445M  4.0K  445M   1% /dev tmpfs          tmpfs     458M     0  458M   0% /dev/shm tmpfs          tmpfs     458M   14M  445M   3% /run tmpfs          tmpfs     458M     0  458M   0% /sys/fs/cgroup /dev/sda4      xfs        47G  2.2G   45G   5% / /dev/sda3      xfs      1014M   86M  929M   9% /boot /dev/sda2      vfat      512M  1.1M  511M   1% /boot/efi /dev/sdb1      ext4      3.9G   16M  3.7G   1% /mnt/resource tmpfs          tmpfs      92M     0   92M   0% /run/user/1000 tmpfs          tmpfs      92M     0   92M   0% /run/user/490

    In the preceding example, we can see that the file system size for the OS disk has been increased.

RHEL with LVM

  1. Access your VM as a root user by using this command:

                    [root@dd-rhel7vm ~]# sudo -i

  2. Use the lsblk command to determine which logical volume (LV) is mounted on the root of the file system (/). In this case, we see that rootvg-rootlv is mounted on /. If you want another file system, substitute the LV and mount point throughout this article.

                    [root@dd-rhel7vm ~]# lsblk -f NAME                  FSTYPE      LABEL   UUID                                   MOUNTPOINT fd0 sda ├─sda1                vfat                C13D-C339                              /boot/efi ├─sda2                xfs                 8cc4c23c-fa7b-4a4d-bba8-4108b7ac0135   /boot ├─sda3 └─sda4                LVM2_member         zx0Lio-2YsN-ukmz-BvAY-LCKb-kRU0-ReRBzh    ├─rootvg-tmplv      xfs                 174c3c3a-9e65-409a-af59-5204a5c00550   /tmp    ├─rootvg-usrlv      xfs                 a48dbaac-75d4-4cf6-a5e6-dcd3ffed9af1   /usr    ├─rootvg-optlv      xfs                 85fe8660-9acb-48b8-98aa-bf16f14b9587   /opt    ├─rootvg-homelv     xfs                 b22432b1-c905-492b-a27f-199c1a6497e7   /home    ├─rootvg-varlv      xfs                 24ad0b4e-1b6b-45e7-9605-8aca02d20d22   /var    └─rootvg-rootlv     xfs                 4f3e6f40-61bf-4866-a7ae-5c6a94675193   /

  3. Check whether there's free space in the LVM volume group (VG) that contains the root partition. If there is free space, skip to step 12.

                    [root@dd-rhel7vm ~]# vgdisplay rootvg --- Volume group --- VG Name               rootvg System ID Format                lvm2 Metadata Areas        1 Metadata Sequence No  7 VG Access             read/write VG Status             resizable MAX LV                0 Cur LV                6 Open LV               6 Max PV                0 Cur PV                1 Act PV                1 VG Size               <63.02 GiB PE Size               4.00 MiB Total PE              16132 Alloc PE / Size       6400 / 25.00 GiB Free  PE / Size       9732 / <38.02 GiB VG UUID               lPUfnV-3aYT-zDJJ-JaPX-L2d7-n8sL-A9AgJb

    In this example, the line Free PE / Size shows that there's 38.02 GB free in the volume group. You don't need to resize the disk before you add space to the volume group.

  4. To increase the size of the OS disk in RHEL 7.x with LVM:

    1. Stop the VM.
    2. Increase the size of the OS disk from the portal.
    3. Start the VM.

  5. When the VM has restarted, complete the following step:

    • Install the cloud-utils-growpart package to provide the growpart command, which is required to increase the size of the OS disk and the gdisk handler for GPT disk layouts. These packages are preinstalled on most marketplace images.
                    [root@dd-rhel7vm ~]# yum install cloud-utils-growpart gdisk

  6. Determine which disk and partition holds the LVM physical volume or volumes (PV) in the volume group named rootvg by using the pvscan command. Note the size and free space listed between the brackets ([ and ]).

                    [root@dd-rhel7vm ~]# pvscan   PV /dev/sda4   VG rootvg          lvm2 [<63.02 GiB / <38.02 GiB free]

  7. Verify the size of the partition by using lsblk.

                    [root@dd-rhel7vm ~]# lsblk /dev/sda4 NAME            MAJ:MIN RM SIZE RO TYPE MOUNTPOINT sda4              8:4    0  63G  0 part ├─rootvg-tmplv  253:1    0   2G  0 lvm  /tmp ├─rootvg-usrlv  253:2    0  10G  0 lvm  /usr ├─rootvg-optlv  253:3    0   2G  0 lvm  /opt ├─rootvg-homelv 253:4    0   1G  0 lvm  /home ├─rootvg-varlv  253:5    0   8G  0 lvm  /var └─rootvg-rootlv 253:6    0   2G  0 lvm  /

  8. Expand the partition that contains this PV by using growpart, the device name, and the partition number. Doing so will expand the specified partition to use all the free contiguous space on the device.

                    [root@dd-rhel7vm ~]# growpart /dev/sda 4 CHANGED: partition=4 start=2054144 old: size=132161536 end=134215680 new: size=199272414 end=201326558

  9. Verify that the partition has resized to the expected size by using the lsblk command again. Notice that in the example sda4 has changed from 63 GB to 95 GB.

                    [root@dd-rhel7vm ~]# lsblk /dev/sda4 NAME            MAJ:MIN RM SIZE RO TYPE MOUNTPOINT sda4              8:4    0  95G  0 part ├─rootvg-tmplv  253:1    0   2G  0 lvm  /tmp ├─rootvg-usrlv  253:2    0  10G  0 lvm  /usr ├─rootvg-optlv  253:3    0   2G  0 lvm  /opt ├─rootvg-homelv 253:4    0   1G  0 lvm  /home ├─rootvg-varlv  253:5    0   8G  0 lvm  /var └─rootvg-rootlv 253:6    0   2G  0 lvm  /

  10. Expand the PV to use the rest of the newly expanded partition:

                    [root@dd-rhel7vm ~]# pvresize /dev/sda4 Physical volume "/dev/sda4" changed 1 physical volume(s) resized or updated / 0 physical volume(s) not resized

  11. Verify that the new size of the PV is the expected size, comparing it to the original [size / free] values:

                    [root@dd-rhel7vm ~]# pvscan PV /dev/sda4   VG rootvg          lvm2 [<95.02 GiB / <70.02 GiB free]

  12. Expand the desired logical volume (LV) by the amount you want. The amount doesn't need to be all the free space in the volume group. In the following example, /dev/mapper/rootvg-rootlv is resized from 2 GB to 12 GB (an increase of 10 GB). This command will also resize the file system.

                    [root@dd-rhel7vm ~]# lvresize -r -L +10G /dev/mapper/rootvg-rootlv

    Example output:

                    [root@dd-rhel7vm ~]# lvresize -r -L +10G /dev/mapper/rootvg-rootlv Size of logical volume rootvg/rootlv changed from 2.00 GiB (512 extents) to 12.00 GiB (3072 extents). Logical volume rootvg/rootlv successfully resized. meta-data=/dev/mapper/rootvg-rootlv isize=512    agcount=4, agsize=131072 blks          =                       sectsz=4096  attr=2, projid32bit=1          =                       crc=1        finobt=0 spinodes=0 data     =                       bsize=4096   blocks=524288, imaxpct=25          =                       sunit=0      swidth=0 blks naming   =version 2              bsize=4096   ascii-ci=0 ftype=1 log      =internal               bsize=4096   blocks=2560, version=2          =                       sectsz=4096  sunit=1 blks, lazy-count=1 realtime =none                   extsz=4096   blocks=0, rtextents=0 data blocks changed from 524288 to 3145728

  13. The lvresize command automatically calls the appropriate resize command for the file system in the LV. Check whether /dev/mapper/rootvg-rootlv, which is mounted on /, has an increased file system size by using this command:

                    [root@dd-rhel7vm ~]# df -Th /

    Example output:

                    [root@dd-rhel7vm ~]# df -Th / Filesystem                Type  Size  Used Avail Use% Mounted on /dev/mapper/rootvg-rootlv xfs    12G   71M   12G   1% / [root@dd-rhel7vm ~]#

Note

To use the same procedure to resize any other logical volume, change the LV name in step 12.

RHEL RAW

To increase the size of the OS disk in an RHEL RAW partition:

  1. Stop the VM.
  2. Increase the size of the OS disk from the portal.
  3. Start the VM.

When the VM has restarted, complete these steps:

  1. Access your VM as a root user by using the following command:

                    [root@dd-rhel7vm ~]# sudo -i

  2. When the VM has restarted, complete the following step:

    • Install the cloud-utils-growpart package to provide the growpart command, which is required to increase the size of the OS disk and the gdisk handler for GPT disk layouts. This package is preinstalled on most marketplace images.
                    [root@dd-rhel7vm ~]# yum install cloud-utils-growpart gdisk

  3. Use the lsblk -f command to verify the partition and filesystem type holding the root (/) partition:

                    [root@vm-dd-cent7 ~]# lsblk -f NAME    FSTYPE LABEL UUID                                 MOUNTPOINT sda ├─sda1  xfs          2a7bb59d-6a71-4841-a3c6-cba23413a5d2 /boot ├─sda2  xfs          148be922-e3ec-43b5-8705-69786b522b05 / ├─sda14 └─sda15 vfat         788D-DC65                            /boot/efi sdb └─sdb1  ext4         923f51ff-acbd-4b91-b01b-c56140920098 /mnt/resource

  4. For verification, start by listing the partition table of the sda disk with gdisk. In this example, we see a 48-GB disk with partition 2 at 29.0 GiB. The disk was expanded from 30 GB to 48 GB in the Azure portal.

                    [root@vm-dd-cent7 ~]# gdisk -l /dev/sda GPT fdisk (gdisk) version 0.8.10  Partition table scan: MBR: protective BSD: not present APM: not present GPT: present  Found valid GPT with protective MBR; using GPT. Disk /dev/sda: 100663296 sectors, 48.0 GiB Logical sector size: 512 bytes Disk identifier (GUID): 78CDF84D-9C8E-4B9F-8978-8C496A1BEC83 Partition table holds up to 128 entries First usable sector is 34, last usable sector is 62914526 Partitions will be aligned on 2048-sector boundaries Total free space is 6076 sectors (3.0 MiB)  Number  Start (sector)    End (sector)  Size       Code  Name    1         1026048         2050047   500.0 MiB   0700    2         2050048        62912511   29.0 GiB    0700 14            2048           10239   4.0 MiB     EF02 15           10240         1024000   495.0 MiB   EF00  EFI System Partition

  5. Expand the partition for root, in this case sda2 by using the growpart command. Using this command expands the partition to use all of the contiguous space on the disk.

                    [root@vm-dd-cent7 ~]# growpart /dev/sda 2 CHANGED: partition=2 start=2050048 old: size=60862464 end=62912512 new: size=98613214 end=100663262

  6. Now print the new partition table with gdisk again. Notice that partition 2 has expanded to 47.0 GiB:

                    [root@vm-dd-cent7 ~]# gdisk -l /dev/sda GPT fdisk (gdisk) version 0.8.10  Partition table scan: MBR: protective BSD: not present APM: not present GPT: present  Found valid GPT with protective MBR; using GPT. Disk /dev/sda: 100663296 sectors, 48.0 GiB Logical sector size: 512 bytes Disk identifier (GUID): 78CDF84D-9C8E-4B9F-8978-8C496A1BEC83 Partition table holds up to 128 entries First usable sector is 34, last usable sector is 100663262 Partitions will be aligned on 2048-sector boundaries Total free space is 4062 sectors (2.0 MiB)  Number  Start (sector)    End (sector)  Size       Code  Name    1         1026048         2050047   500.0 MiB   0700    2         2050048       100663261   47.0 GiB    0700 14            2048           10239   4.0 MiB     EF02 15           10240         1024000   495.0 MiB   EF00  EFI System Partition

  7. Expand the filesystem on the partition with xfs_growfs, which is appropriate for a standard marketplace-generated RedHat system:

                    [root@vm-dd-cent7 ~]# xfs_growfs / meta-data=/dev/sda2              isize=512    agcount=4, agsize=1901952 blks          =                       sectsz=4096  attr=2, projid32bit=1          =                       crc=1        finobt=0 spinodes=0 data     =                       bsize=4096   blocks=7607808, imaxpct=25          =                       sunit=0      swidth=0 blks naming   =version 2              bsize=4096   ascii-ci=0 ftype=1 log      =internal               bsize=4096   blocks=3714, version=2          =                       sectsz=4096  sunit=1 blks, lazy-count=1 realtime =none                   extsz=4096   blocks=0, rtextents=0 data blocks changed from 7607808 to 12326651

  8. Verify the new size is reflected by using the df command:

                    [root@vm-dd-cent7 ~]# df -hl Filesystem      Size  Used Avail Use% Mounted on devtmpfs        452M     0  452M   0% /dev tmpfs           464M     0  464M   0% /dev/shm tmpfs           464M  6.8M  457M   2% /run tmpfs           464M     0  464M   0% /sys/fs/cgroup /dev/sda2        48G  2.1G   46G   5% / /dev/sda1       494M   65M  430M  13% /boot /dev/sda15      495M   12M  484M   3% /boot/efi /dev/sdb1       3.9G   16M  3.7G   1% /mnt/resource tmpfs            93M     0   93M   0% /run/user/1000