Concepts — Disks
Architecture
A Hikube disk is a persistent block volume belonging to a project. It consumes the project's storage quota and can be attached to a virtual machine in the same project.
Terminology
| Term | Description |
|---|---|
| Disk | Persistent block storage volume, managed from the Infrastructure → Disks menu. |
| Empty Disk | Raw data disk, to format and mount in the VM (shown as Data Disk in the list). |
| System Disk | Disk created from a system image, usable as the boot disk of a VM. |
| Cloud image | Operating system image from the Hikube catalog, chosen by OS and version. |
| Custom image | ISO or QCOW2 image imported from an HTTPS URL that you provide. |
| Replication | Copy of the disk data across several nodes, in synchronous or asynchronous mode. |
| Encryption (LUKS) | Encryption of data at rest on the disk. |
| Attached to | VM currently using the disk. |
Statuses
| Status | Meaning |
|---|---|
| Creating | The disk is being provisioned |
| Downloading | The image of a system disk is being imported; progress is shown as a percentage |
| Ready | The disk is provisioned and not attached to any VM |
| In Use | The disk is attached to a VM |
| Error | The image download or the provisioning failed |
| Unknown | The disk status could not be determined yet |
Disk source
The Source step of the wizard offers two choices:
- Empty Disk: "Raw storage space that can be formatted and mounted on a virtual machine."
- System Disk: "A disk containing a pre-installed operating system." You then choose an image in OS Image / Source:
- a cloud image from the catalog (OS, then Version);
- or Custom Image: an Image URL (ISO/QCOW2). The URL must use HTTPS; private or local IP addresses are rejected.
A Windows system disk must be at least 50 GB. Its estimated cost includes the Windows license.
Replication
| Mode | Label | Behavior | RTO | RPO |
|---|---|---|---|---|
| Asynchronous | Asynchronous Replication (Recommended) | Deferred replication: if several nodes fail simultaneously, a small amount of recent data may be lost | < 5 min | < 5 min |
| Synchronous | Synchronous Replication | Real-time replication across several nodes: minimal data loss in case of failure | < 5 min | < 1 min |
Asynchronous Replication is selected by default.
Encryption
The Disk Encryption toggle enables LUKS encryption of data at rest. An encrypted disk is flagged with the Encrypted badge in the list and uses a different rate.
The source, replication and encryption are chosen at creation. Only the size of a disk can be changed afterwards, and only upwards.
Size and quota
- Minimum size: 20 GB (50 GB for a Windows system disk).
- The size is limited by the project's storage quota; the wizard displays the Estimated project usage gauge.
- A disk can be expanded, never shrunk (see Resize a disk).
Pricing
The wizard displays an Estimated Cost: the rate per GB per month, and the monthly cost of the disk. The rate depends on encryption; a Windows system disk adds the license cost.
Limits
| Parameter | Value |
|---|---|
| Disk name | 3 to 16 characters: lowercase letters, digits and hyphens; starts with a letter, ends with a letter or a digit |
| Size | From 20 GB, within the limit of the project's storage quota |
| Attachment | A single VM at a time |
| Size reduction | Not supported |
Further reading
- Quick start: create a disk and use it in a VM
- Attach a disk to a VM
- Create a system disk from an image