Ephemeral storage is a storage device attached to- and mounted in some virtual machines. Whether your VM has ephemeral storage attached, depends on its flavor. More information about flavors and availability is below.
Ephemeral storage is typically attached to the instance as '/dev/vdb' and it is formatted and mounted under '/mnt' upon launch.
Data stored on ephemeral disk is only persistent until the termination or rebuild of the virtual machine similar to the root disk. IMPORTANT: the data on the ephemeral disk is not included when taking a snapshot of a virtual machine. You cannot use snapshot to save or back up your data on ephemeral storage.
"IMPORTANT: any data on the ephemeral disk is not included in a snapshot"
In a new instance you may have to change ownership or write privileges to enable writing to the ephemeral storage, using chown, chgrp or chmod, e.g.
$ sudo chown ubuntu:ubuntu /mnt
* your use-case or operating system may require a different approach than this example.
When resizing an instance, the filesystem on the ephemeral storage does not resize. Refer to the documentation for Resizing Nectar instances
Flavors and availability
Nectar's first generations of public flavors, known as m1 and m2 flavors, included ephemeral storage. New flavors introduced in 2018 do not include ephemeral storage. The m1 and m2 flavors that have ephemeral storage are deprecated and are being phased out. Users launching instances based on Nectar's new flavors are encouraged to use Volume storage instead.
Nectar nodes can provision projects with specialty private flavors, some of which have ephemeral storage attached, ranging from 10GB to 5TB. At different nodes the ephemeral storage can have different characteristics (e.g. performance) Contact your node representative or firstname.lastname@example.org to discuss whether ephemeral storage is suitable for your use case and arrange access to specialty private flavors.