Attaching and Detaching Additional Volumes

Attaching a Block Storage Volume makes its storage accessible to a Cloud Server.

This guide covers attaching an already existing Volume, if you haven’t created any yet there is a separate guide for creating new Volumes.

Attaching a Volume

In Control Panel, choose Volumes from the sidebar and find the Volume you wish to attach.

The Attached to item will show whether the volume is currently attached to a Cloud Server:

To attach the Volume, click the Attach button. You’ll be presented with the “Attach Volume” panel with a list of available Cloud Servers to choose from.

Choose the Cloud Server you want to attach the volume to and click Save.

You’ll be presented with a confirmation dialogue, click Attach Volume to confirm and the volume will then be attached to the Cloud Server.

Now that the volume has been attached, you’ll be presented with a confirmation dialog with some instructions for mounting the volume, prefilled with the volume details, which you can copy and paste but we’ll go through the manual steps here to explain everything.

View attached Volumes

In this example we’re using a volume with a filesystem labelled data.

We can confirm the volume has been attached by logging into the Cloud Server via SSH and using lsblk -f to list the available block devices with their filesystems:

$ lsblk -f -I 252
NAME    FSTYPE LABEL           UUID                                 FSAVAIL FSUSE% MOUNTPOINT
vda
├─vda1  ext4   cloudimg-rootfs c545d079-6483-492d-a078-e32869326a2a     36G     7% /
├─vda14
└─vda15 vfat   UEFI            33A2-2A84                              99.2M     5% /boot/efi
vdb     ext4   data            9ab8824f-efd2-4279-a4e7-6e39ec85c214

We can see there is an additional device named vdb, with an ext4 filesystem labelled data which isn’t currently mounted (we’re also using the -I option here to simplify the results to only include devices that we’re interested in).

Formatting the Volume

If you didn’t specify an ext4 or xfs filesystem during volume creation, you’ll need to format the volume manually before mounting.

Mount the Volume

Create the mount point

We need to create a directory which will serve as the mount point for the volume i.e. the location where the volume will be accessed within the Cloud Server:

$ sudo mkdir -p /mnt/data

Mount the Volume

We now need to mount the volume to the mount point we created above. We can make use of persistent device naming here to reference the volume.

Using the Volume serial

The volume serial can be customised but defaults to the volume id:

$ sudo mount /dev/disk/by-id/virtio-vol-3n0qb /mnt/data

Using the filesystem label

If you specified a filesystem label during volume creation you can use this instead, along with the mount -L option:

$ sudo mount -L data /mnt/data

We can now use lsblk -f to confirm that the filesystem is now mounted:

$ lsblk -f
NAME    FSTYPE   LABEL           UUID                                 FSAVAIL FSUSE% MOUNTPOINT
loop0   squashfs                                                            0   100% /snap/core20/1405
loop1   squashfs                                                            0   100% /snap/lxd/22526
loop2   squashfs                                                            0   100% /snap/core20/1434
loop3   squashfs                                                            0   100% /snap/lxd/22753
loop4   squashfs                                                            0   100% /snap/snapd/15177
loop5   squashfs                                                            0   100% /snap/snapd/15534
vda
├─vda1  ext4     cloudimg-rootfs c545d079-6483-492d-a078-e32869326a2a     36G     7% /
├─vda14
└─vda15 vfat     UEFI            33A2-2A84                              99.2M     5% /boot/efi
vdb     ext4     data            9ab8824f-efd2-4279-a4e7-6e39ec85c214   46.4G     0% /mnt/data

Configure fstab for auto-mounting

To ensure that the volume is mounted automatically following a reboot, we also need to add an entry to the Cloud Server’s /etc/fstab

$ echo 'LABEL=data /mnt/data ext4 defaults,nofail,discard 0 0' | sudo tee -a /etc/fstab

We can verify our fstab entry using findmnt:

$ sudo findmnt --verify
Success, no errors or warnings detected

Detaching a Volume

Detaching a volume is pretty much the reverse of attaching a volume and will leave the volume in the detached state, which means it is available to be attached to another cloud server, or can be deleted.

Unmount the volume

To avoid data loss, it’s important to either shutdown the cloud server so that it enters the inactive state, or unmount the volume within the cloud server:

$ sudo umount /mnt/data

We can confirm the filesystem was unmounted using lsblk -f where we can see that there is now no entry in the mountpoint column.

$ lsblk -f
NAME    FSTYPE   LABEL           UUID                                 FSAVAIL FSUSE% MOUNTPOINT
loop0   squashfs                                                            0   100% /snap/core20/1405
loop1   squashfs                                                            0   100% /snap/lxd/22526
loop2   squashfs                                                            0   100% /snap/core20/1434
loop3   squashfs                                                            0   100% /snap/lxd/22753
loop4   squashfs                                                            0   100% /snap/snapd/15177
loop5   squashfs                                                            0   100% /snap/snapd/15534
vda
├─vda1  ext4     cloudimg-rootfs c545d079-6483-492d-a078-e32869326a2a     36G     7% /
├─vda14
└─vda15 vfat     UEFI            33A2-2A84                              99.2M     5% /boot/efi
vdb     ext4     data            9ab8824f-efd2-4279-a4e7-6e39ec85c214

We should also make sure to delete any entries we made in /etc/fstab.

Detach the volume

Now that the filesystem is unmounted, we can go ahead and detach the volume from the cloud server.

In the volume view we can see that the volume is currently attached:

Click the Detach button and you’ll be presented with a warning dialogue, click Detach Volume to confirm and the volume will be now be detached from the cloud server.