> 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.md).

# Block Storage

Glesys Block Storage gives you flexible storage that can grow and move with your infrastructure.

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Glesys Block Storage provides persistent block-level storage for KVM virtual machines, allowing storage to be managed separately from the virtual machine's local system disk.

Block Storage volumes can be attached to and detached from KVM virtual machines, moved between virtual machines, and increased in size while the virtual machine is running. Choose between three performance tiers based on your storage requirements.

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Block Storage is currently available for KVM virtual machines in our Falkenberg data center in Sweden.
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### How Block Storage works

Block Storage provides storage as volumes that can be attached to KVM virtual machines. A volume is presented to the operating system as a raw block device, similar to an additional disk.

Unlike the virtual machine's local system disk, a Block Storage volume is managed separately from the virtual machine. This allows you to manage compute and storage independently and move a volume between KVM virtual machines when needed.

Block Storage can be understood through two main components:

1. **Volume:** A persistent block storage device with a selected capacity and performance tier. Volumes are created and managed separately from KVM virtual machines.
2. **KVM virtual machine:** A virtual machine to which a Block Storage volume can be attached. For the operating systems documented by Glesys, volumes can be added and removed while the virtual machine is running.

Block Storage volumes are provided as raw block devices. You are responsible for creating the filesystem and, where applicable, partitioning and mounting the volume.

## Performance tiers

When creating a Block Storage volume, you choose between three performance tiers:

**Capacity** provides up to 1,200 read and write IOPS.

**Balanced** provides up to 12,000 read and write IOPS.

**Velocity** provides up to 120,000 read IOPS and 30,000 write IOPS.

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

### Managing volumes

Block Storage volumes can be attached to and detached from KVM virtual machines. They can also be moved between KVM virtual machines.

The size of an existing volume can be increased while the virtual machine is running. After increasing a volume, you may also need to extend the partition or filesystem in the operating system to use the additional capacity.

Existing volumes cannot be reduced in size. To use a smaller volume, create a new volume with the required capacity and copy your data to it.

## Guides and documentation

<table data-card-size="large" data-view="cards"><thead><tr><th></th><th></th><th data-hidden data-card-target data-type="content-ref"></th></tr></thead><tbody><tr><td><strong>Quickstart</strong></td><td>Get up and running quickly with Block Storage.</td><td><a href="/products/storage/block-storage/quickstart.md">Quickstart</a></td></tr><tr><td><strong>How-tos</strong></td><td>Detailed guides on how to create, attach, manage, resize, move, and delete Block Storage volumes.</td><td><a href="/products/storage/block-storage/how-tos.md">How-tos</a></td></tr><tr><td><strong>Details</strong></td><td>All the details for the Block Storage service.</td><td><a href="/products/storage/block-storage/details.md">Details</a></td></tr><tr><td><strong>FAQ</strong></td><td>Frequently Asked Questions about Glesys  Block Storage.</td><td><a href="/products/storage/block-storage/faq.md">FAQ</a></td></tr></tbody></table>