Volume is the main storage for instance data.
All volumes are attached via VirtIO protocol and thus, require special support from the OS. All OS images officially supported by CROC Cloud already contain pre-installed drivers.
To ensure maximum performance of volume subsystem, we recommend you to attach multiple volumes and then create a single striped volume of them.
There are two volume types in terms of lifecycle – automatic volumes and user volumes. Automatic volumes are automatically created at the instance launch and deleted when the instance is terminated. User volumes are created by user independently of the instance and can be attached to any instance.
If an automatically created volume is detached from the instance, it becomes a user volume and will not be deleted with the termination of instance.
Each new volume is either an empty volume or a copy of master snapshot. Master snapshots contain an installed and configured OS, and are mostly used for system volumes. Volume created from master snapshot may exceed the master volume in size.
In this case, additional empty space appears on such Volume. Later on, you can use this empty space to create additional partition or expand the file system, so that it occupies the entire Volume.
You can increase the Volume size after its creation as well. However, this operation can only be performed with disconnected Volumes.
Volume subsystem performance can be selected depending on the task to be solved. The most common configurations suitable for most of applications are selected as templates:
- basic configurations;
- high-memory configurations;
- high-compute configurations.
Each volume has a set of parameters:
- ID – volume unique ID.
- Description – contains volume description. Can be modified by user
- Status – contains information about volume status
- Availability Zone – data center in which physical hardware is located
- Type – indicates Volume type: Universal/Flash
- Size – maximum amount of data that a volume can hold
- Creation date
Universal (API name:
- placed on magnetic disks
- 500 IOPS guaranteed performance
- maximum throughput in MB/s is calculated using the following formula:
Max (MB/s) = Size (GB) * 0.25 (MB/s per GB), but not less than 8 MB/s.
- volume size must be multiple of 8 GB
- minimum volume size is 32 GB
- maximum throughput shall be recalculated each time the volume size is increased
Flash (API name:
- flash drives
- guaranteed performance of up to 100,000 IOPS
- support of changing IOPS “on the go”
Creating a volume¶
Click button to create new volume.
A new Volume creation dialog will open. You can use different methods to create new volume:
- Create an empty Volume
- Create a volume from an image
Creating an empty volume¶
In the new Volume creation window, select Create Empty Volume. Set the required parameters: Volume size, accessibility area, and click button.
Creating a volume from an image¶
To create a Volume from an image, select Create Volume From Image. You can either create Snapshots yourself (link to Snapshots section) or use CROC Snapshots.
Set the required parameters of new Volume and click button.
A unique ID is Allocated to the created Volume in vol-xxxxxxxx format. To facilitate Volumes handling, we recommend you to prepare their brief descriptions.
Attaching a Volume to an instance¶
To attach a Volume to an instance, if this Volume is created and not attached to another instance (see Volumes section), click .
Creating a snapshot¶
Click button to create a snapshot, which can be used later to create a template.
Displaying volume properties¶
Click a link with unique ID to display detailed volume information.
The tab contains a detailed description of the device, creation date, cluster, in which the Volume is located, size, and storage type. Click button to edit the Volume name.
The tab displays the Volume read/write rate statistics. You can display statistics for current or selected time period.
Click More… to open a list of additional shared actions with the selected Volume.
Deleting a volume¶
Click Delete to delete the device.
Attention! This function is available only for instance with “Stopped” status!
Changing a volume description¶
Click Change Description to edit an instance name.
Increasing volume size¶
Click Increase volume size to increase the volume size. Set the volume size in the dialog window. There is no need to stop the instance.
Click Change iops to change IOPS value for the current flash volume.
Attention! This function is available only for flash volumes!
Detaching from instance¶
Click Detach from instance to detach the volume from instance and the volume will be available for the next attachment.