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Expanding an OCI boot volume online and growing the filesystem

Resize a boot or block volume without stopping the instance, rescan the device, and extend the filesystem with oci-growfs on Oracle Linux or manually elsewhere.

Deepak Bhardwaj2 min read

Applies toOCI Block Volume (boot and data volumes), Oracle Linux 7/8/9, Windows Server

1. Back up, then resize the volume

oci bv boot-volume-backup create --boot-volume-id $BV --type INCREMENTAL \
  --display-name "pre-resize-$(date +%F)" --wait-for-state AVAILABLE

oci bv boot-volume update --boot-volume-id $BV --size-in-gbs 200 --wait-for-state AVAILABLE
# block (data) volume:
oci bv volume update --volume-id $VOL --size-in-gbs 1024 --wait-for-state AVAILABLE

Online resizing is supported, so the instance can stay running. Volumes can only grow.

2. Rescan the device in the guest

The OS doesn't see the new size until the device is rescanned. On Oracle Linux, the console shows the exact commands after a resize. The pattern is:

sudo dd iflag=direct if=/dev/oracleoci/oraclevda of=/dev/null count=1
echo "1" | sudo tee /sys/class/block/$(readlink /dev/oracleoci/oraclevda | cut -d'/' -f 2)/device/rescan
lsblk

For iSCSI-attached data volumes, rescan the session instead: sudo iscsiadm -m node -R.

3. Grow the root filesystem (Oracle Linux)

sudo /usr/libexec/oci-growfs -y
df -h /

oci-growfs extends the partition, the LVM physical and logical volumes where present, and the filesystem (XFS or ext4) in one step.

3b. Other distributions

sudo growpart /dev/sda 1        # adjust disk and partition number (lsblk)
sudo xfs_growfs /               # XFS
sudo resize2fs /dev/sda1        # ext4

3c. Windows

Open Disk Management → Action → Rescan Disks, then right-click the volume → Extend Volume. Or:

Update-HostStorageCache
Resize-Partition -DriveLetter C -Size (Get-PartitionSupportedSize -DriveLetter C).SizeMax

Performance as well as size

Block volume performance scales with size and the VPUs/GB setting (Lower Cost, Balanced, Higher Performance, Ultra High Performance). If the customer's real complaint is slow disk, raise VPUs instead of, or as well as, size:

oci bv volume update --volume-id $VOL --vpus-per-gb 20

Or enable performance auto-tune so OCI adjusts it.

Tip

Put application data on separate block volumes. Growing a data volume is simpler and safer than repeatedly resizing the boot volume.

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