---
title: "Features"
description: "Read-write mounts, low-latency access, resizing, and encryption for Block Storage disks"
---

import { BlockStorageFeaturesNav, BlockStorageBestPracticesCard } from './BlockStorageCards'

# Features

What a Block Storage disk can do, and the limits that come with it.

<BlockStorageFeaturesNav />

---

## Read-Write Mounts

A disk mounts at `/datasets/<name>` with **write access**. This is the main reason to choose it over [Object Storage](/docs/tir/object-storage/), which mounts read-only: anything that downloads, unpacks, transforms, or checkpoints into its mount directory needs a disk.

A disk attaches to one resource at a time. If it is already mounted elsewhere, the portal reports it as already mounted rather than attaching it twice.

---

## Low-Latency Access

The disk is attached directly to the workload it is mounted on, so random reads and writes are fast and local. That makes it the right place for:

- Scratch space during data preparation.
- A cache in front of a larger Object Storage bucket.
- Checkpoints written frequently during long training runs.

For data that must be read concurrently by many nodes, use [SFS](/docs/tir/sfs/) or [PFS](/docs/tir/pfs/) instead.

---

## Resizable Capacity

A disk is created at a fixed size — minimum 10 GB, 100 GB by default — and can be increased at any time from the **Resize Disk** tab, up to your project's storage limit.

:::warning Growth is one-way
A disk can never be reduced. You are billed on the allocated size regardless of how much you use, so over-provisioning costs money you cannot recover without creating a smaller disk and migrating.
:::

If you hit the project ceiling, the resize panel offers a **Request** button that submits a limit increase for review. See [Grow the Disk Later](./QuickStart.mdx#grow-the-disk-later).

---

## Encryption

Block Storage supports encryption at rest with **E2E Managed** keys. Turn it on with the **Enable Encryption** switch when creating the disk; user-managed keys are not offered for disks.

Encryption is set at creation and cannot be changed afterwards, and it is free of cost. It is not available in every region — where it is unavailable, the switch does not appear on the create form.

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## What Block Storage Does Not Provide

A disk is deliberately narrower than an Object Storage bucket. There is **no** S3 endpoint, access key, data-object browser, upload dialog, lifecycle rule, versioning, object lock, presigned URL, or replication. Data goes in and out through the workload the disk is mounted on.

If you need any of those, use [Object Storage](/docs/tir/object-storage/).

---

<BlockStorageBestPracticesCard />