> For the complete documentation index, see [llms.txt](https://docs.glesys.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.glesys.com/products/storage/block-storage/faq.md).

# FAQ

Frequently asked questions about Glesys Block Storage.

***

Here we have compiled frequently asked questions and answers concerning the Glesys Block Storage service. If you do not find the answer to your question, you are welcome to contact our support at [support@glesys.com](mailto:support@glesys.se).

### What is a Block Storage volume?

A Block Storage volume provides persistent storage that can be attached to a KVM virtual machine and used like an additional disk.

The volume is managed separately from the virtual machine's local system disk and is presented to the operating system as a raw block device.

### Can I attach or detach a volume while the virtual machine is running?

Yes. Hot add and hot remove are supported for the operating systems and versions listed in the Block Storage documentation.

Currently documented support includes Ubuntu 18.04 and later, Debian 10 and later, AlmaLinux, Talos, Windows Server 2022 and later, and OPNsense.

### Can I move a Block Storage volume between KVM virtual machines?

Yes. A Block Storage volume can be moved between KVM virtual machines.

Before moving a volume, unmount and/or eject it from the operating system and detach it from the current virtual machine. The volume can then be attached to another virtual machine.

A Block Storage volume can only be attached to one virtual machine at a time.

### Can I attach a Block Storage volume to multiple virtual machines at the same time?

No. A Block Storage volume can only be attached to one KVM virtual machine at a time.

To use the volume with another virtual machine, detach it from the current virtual machine before attaching it to the new one.

### What happens to my Block Storage volume if I delete the virtual machine?

If a virtual machine is deleted, the attached Block Storage volume is automatically detached. The volume and its data remain available, and the volume can be attached to another KVM virtual machine.

### Am I still charged for a Block Storage volume if I delete the virtual machine?

Yes. Block Storage volumes are managed and billed separately from the virtual machine. If the virtual machine is deleted, the Block Storage volume remains available and billing continues until the volume itself is deleted.

### Is there a limit to how many drives can be attached to a KVM virtual machine?

A KVM virtual machine can have a maximum of 25 drives attached in total.

This limit includes Block Storage volumes and other drives attached to the virtual machine.

### Can I increase the size of an existing volume?

Yes. You can increase the size of a Block Storage volume while the virtual machine is running.

After increasing the volume, the partition and/or filesystem may also need to be extended inside the operating system before the additional capacity can be used.

### Can I decrease the size of an existing volume?

No. Downsizing an existing Block Storage volume is not supported.

To reduce the provisioned capacity, create a new, smaller volume and copy the required data from the existing volume to the new volume.

### What is the minimum and maximum volume size?

Block Storage volumes can be provisioned from 1 GiB up to 2,048 GiB.

The same size range applies to Capacity, Balanced, and Velocity.

### What performance tiers are available?

Block Storage is available in three performance tiers:

* **Capacity:** up to 1,200 read and 1,200 write IOPS
* **Balanced:** up to 12,000 read and 12,000 write IOPS
* **Velocity:** up to 120,000 read and 30,000 write IOPS

The specified IOPS values are up-to limits and are not guaranteed performance levels.

### Can I change the performance tier of an existing Block Storage volume?

No. The performance tier of an existing Block Storage volume cannot currently be changed through the Glesys Control Panel.

### Are there backups of Block Storage volumes?

No. Glesys Backup currently does not support Block Storage volumes.

If data stored on a Block Storage volume requires backup, you are responsible for implementing an appropriate backup solution.

### Where is Block Storage available?

Block Storage is currently available in dc-fbg1 (our Falkenberg DC, Sweden).