Resize and Extend Block Volumes on OCI Compute Instances

Applies to: OCI Linux compute instances with OCID block volumes
Goal: Increase a block volume’s size and extend the filesystem on the instance so that extra space becomes usable.

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✅ Prerequisites

• A running OCI Compute instance with a block volume attached (e.g. /dev/sdb)
• Sudo access on the Linux instance
• Current block volume size (e.g. 50 GB)
• Understanding of partitions, logical volumes (if applicable), and filesystems (e.g. ext4, XFS)

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First step is to resize the block volume in OCI

Step 1 : Increase size in console.

Note :- The existing size is 50 GB.

1. Select the Edit option on the Block Volume page.

2. Enter the new size you want for the volume and click on save changes.

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Step 2 : Increase Disk Size

After saving the changes, we get the "Resize Block Volume" box containing the volume rescan commands, as shown below. These 2 commands need to be copied and run in the Linux server(via Putty) to increase the size of the block volume.

Note :- After running the volume rescan commands, we also need to extend the partition for the volume resize to take effect

1. Before running the volume rescan commands, we need to check the size of block volume using "lsblk" command

lsblk

2. We also need to run the command "lsblk -ap /dev/sdb | head -2" to check the current size of the specific disk, which we want to increase

lsblk -ap /dev/sdb | head -2

3. This is an important step. We need to **Edit **the copied rescan commands according to the actual disk name in the Linux we want to upgrade

Copied rescan commands

sudo dd iflag=direct if=/dev/oracleoci/oraclevdb of=/dev/null count=1

echo "1" | sudo tee /sys/class/block/`readlink /dev/oracleoci/oraclevdb | cut -d'/' -f 2`/device/rescan

Updated rescan commands

sudo dd iflag=direct if=/dev/sdb of=/dev/null count=1

echo "1" | sudo tee /sys/class/block/sdb/device/rescan

4. Run the lsblk command to check whether the disk size is increased or not

lsblk

lsblk -ap /dev/sdb | head -2

5. We can see that the disk size is increased

6. However, logical volume & partition size is still not increased

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Step 3 : Verify in Linux server whether the partition exists

Run the command "sudo parted /dev/sdb print" to check the Disk and the partition size

sudo parted /dev/sdb print

In the output shown below, we can see that the disk size has increased, but the partition size remains the same as before.

Note :- Even though we are increasing the volume size from 50 to 70 GB, the disk size shows as 75.2 GB. This is coz Oracle gives some extra space.

Step 4 : **Grow **the partition size to the new size - 70 GB

1. Use the command "sudo growpart /dev/sdb 1" to grow the partition

sudo growpart /dev/sdb 1

2. We are able to see both the old and new size of partition

3. Again run the partition command and check the size of part. The size of the partition is now increased.

sudo parted /dev/sdb print.

4. Run lsblk command and check size of disk and partition

lsblk

As we can see, the size of disk and partition has increased, but logical volume

5. Now, run the command to display detailed information about a specific logical volume (lv_u01) in a volume group (vg_u01)

lvdisplay -am /dev/mapper/vg_u01-lv_u01

The logical volume is still the same as before; it has not increased yet

6. Next step is to Resize the Physical Volume using the below commands

pvresize /dev/sdb1 pvdisplay /dev/sdb1

Physical volume still display the old volume in allocated PE

7. We can check volume group allocated PE also

vgdisplay vg_u01

in below screen, we can see total PE, allocated PE and free PE

8. As we can see below, Logical volume size is still not increased

9. To increase the Logical volume size, we need to Extend the Logical volume size using the command below

lvextend -l +100%FREE /dev/mapper/vg_u01-lv_u01

10. Logical volume is increased now. However "df -h" still shows the old value

11. The last step is to resize the file system to extended 20 GB with right file format

resize2fs /dev/mapper/vg_u01-lv_u01

12. Finally, as shown in the screen below, running df -h confirms that the logical volume has been extended to the required size

8. ✅ Summary

In this lab, we increased the size of an OCI block volume and extended it all the way into our OS’s filesystem.
We learned to:

• Resize the block volume via OCI console
• Rescan the block device inside Linux
• Grow partition and/or LVM structures (PV, VG, LV)
• Expand the filesystem (ext4/XFS) to make the extra space usable

This operation is essential during scale-ups, storage extensions, or when application load grows.