Storage

In a Nutshell

If you need more storage in a VM, create and attach additional volumes — root disks cannot be resized. Using special flavors with larger root disks as a reserve for extra storage is generally discouraged, as they offer less flexibility. All data is stored redundantly (e.g., 3× replication in Ceph), but no automatic backups are performed — you are responsible for backing up your own data. Back up your data regularly using snapshots or by downloading (volume-)images using the OpenStack client as explained here. ⚠️ To avoid data loss: Never store critical or irreplaceable data only in bwCloud-OS — always back up externally.

Volumes (Block Devices)

What should I do if the root disk of my VM becomes too small?

The size of the root disk (system disk) cannot be increased after the VM is created. If you need more storage, the recommended solution is to attach additional volumes (virtual disks) to your instance.

If your current quota is not sufficient to create the needed volumes, please submit a ticket to increase your volume quota via the bwSupportPortal.

The following guide walks you through all required operations.

➡️ Volumes and Images Guide

Backups

Does bwCloud-OS provide a dedicated interface for backups?

No, bwCloud-OS does not offer a dedicated interface for backups or data protection. However, you can back up your instance data using standard tools and methods, see below.

How can I back up my virtual machines?

You can back up your VMs in bwCloud-OS in several ways:

🔹 Snapshots via the Dashboard

• You can create snapshots of both instances and volumes using the web interface.
• Instance snapshots are saved as images and can be downloaded using the CLI, see here for instructions.
• You can also convert volumes into images and download them the same way, see here for instructions.

🔹 Export data directly from the instance

• For large volumes or more control, it's often easier and more efficient to back up data directly from inside the VM using standard tools such as rsync, scp, or other backup utilities.

Can I export or import a (volume-)image?

Yes, that is possible. However, you should use the OpenStack CLI Client. The main commands can be found in the following guide.

➡️ Volumes and Images Guide

How secure is my data (in terms of integrity) in bwCloud-OS?

Both the system disk (root disk) of a virtual machine and any attached volumes are stored redundantly, either in our distributed Ceph storage systems (most regions) or another redundant storage system (Freiburg). Each piece of data has redundancy level 3, which provides robust protection against individual hardware failures.

However, please note:

• No regular backups of VM data are performed. By default, neither the root disk nor attached volumes are backed up.
• It is your responsibility to ensure that important data is backed up internally (e.g. via snapshots) and externally (using external backup systems).

⚠️ Important Operational Note

bwCloud-OS is operated as a "best-effort" infrastructure service. This means:

• To maintain performance and affordability, the system does not include mechanisms such as geo-redundancy.
• In very rare cases (e.g., multiple simultaneous disk failures or critical software bugs in Ceph), data loss may occur and recovery may not be possible.

For this reason, we strongly recommend storing critical or irreplaceable data (including essential configuration files and recovery information) on external storage systems outside the bwCloud-OS.

Storage Performance

Is storage throughput in the bwCloud-OS throttled?

Yes. Storage performance in bwCloud-OS is intentionally throttled to ensure fair usage across all users.

All data — including root disks and attached volumes — is stored in the Ceph distributed storage system, which is connected to the compute hosts via the internal network. This means that the storage performance depends on shared network resources: The more simultaneous activity there is, the more the available bandwidth is divided among users.

To ensure fair access, each instance is limited to a maximum of 100 MB/s (full duplex) and 800 IOPS.

This limitation helps maintain consistent performance in a multi-user environment and prevents individual VMs from monopolizing bandwidth.

Can I request higher storage throughput in bwCloud-OS?

Yes, in justified cases, higher data throughput can be granted.

Please submit a support ticket, including the following required information:

• A short note that you are requesting higher storage throughput
• A description of your use case or application and why the increased throughput is needed
• Your OpenStack user ID
• The region where the increased throughput is required