A volume will not attach or mount

Adding a volume has two stages, and problems usually sit in one of them: attaching it to the server, and mounting it inside the server.

It will not attach

• Confirm the volume and the server are in the same region. A volume can only attach to a server in its own region.
• Confirm the volume is available (not already attached to another server). Detach it from the old server first.

It attaches but the server does not see it

Attaching makes the disk visible to the operating system, but you still have to prepare it once.

1. Log in over SSH and run lsblk to see the new disk (often /dev/vdb or similar).
2. If it is brand new, create a filesystem on it, then mount it to a folder.
3. Add it to /etc/fstab so it mounts automatically after a reboot. A missing fstab entry is the usual reason a mounted volume "disappears" after restarting.

Never format a volume that already holds data; formatting erases it. If in doubt, take a snapshot first.