> ## Documentation Index
> Fetch the complete documentation index at: https://docs.cockroachlabs.com/llms.txt
> Use this file to discover all available pages before exploring further.
# Cockroach Plenum Overview
export const InternalLink = ({version, path = "", children, ...props}) => {
let detectedVersion = version || "stable";
if (typeof window !== 'undefined' && !version) {
const match = window.location.pathname.match(/\/docs\/([^/]+)/);
if (match) {
detectedVersion = match[1];
}
}
const normalizedPath = path.startsWith("/") ? path.slice(1) : path;
return
{children}
;
};
**This feature is in preview** and subject to change. To share feedback and/or issues, contact [Support](https://support.cockroachlabs.com).
Cockroach Plenum is Cockroach Continuum's elastic storage layer that separates a cluster's storage from its compute. Plenum provides a custom storage architecture purpose-built for CockroachDB that preserves CockroachDB's existing replication and consensus behavior while removing reliance on a provisioned disk layer.
On Continuum, Plenum backs the [*usage-based* storage model](#usage-based-storage), available on eligible Mission Critical clusters. Usage-based storage is billed based on physical-used GiB rather than provisioned capacity.
## How it works
CockroachDB nodes write to Plenum through the storage layer instead of writing to attached disks. Plenum manages the physical placement and redundancy of stored data across availability zones. Above the storage-layer boundary, SQL, transaction, and replication behavior remains unchanged.
## Compared to provisioned storage
With provisioned block storage, each node has its own attached volume, so storage and compute are sized and scaled together as a unit. You provision capacity for the data you expect, pay for it whether or not it is full, and resize it as data grows. Provisioned block-storage services such as Amazon EBS also replicate data internally, adding cost and redundancy on top of CockroachDB's replication.
Plenum removes the provisioned-disk layer entirely. CockroachDB nodes write to a shared storage service instead of to attached disks, and storage is billed based on physical-used GiB.
## Usage-based storage
When you create a Mission Critical cluster, you choose its storage model:
* *Usage-based.* Storage is backed by Plenum. You do not provision storage capacity or bandwidth. Storage capacity scales automatically as data is added or removed. You are billed based on physical-used GiB, and the Console shows storage consumption rather than provisioned capacity.
* *Provisioned.* Storage is backed by conventional block volumes and billed as provisioned capacity.
Usage-based storage is available on single-region Mission Critical clusters running CockroachDB v26.3 or later. Multi-region Mission Critical clusters and host clusters use provisioned storage.
Plenum is initially available in the following AWS regions:
* `us-east-1`
* `us-west-2`
* `eu-central-1`
* `eu-west-1`
Standard clusters run on shared infrastructure with usage-based storage billing, separate from Plenum.
The storage model is chosen when you create the cluster, and cannot be changed. To change storage models, create a new cluster and move the workload.
For details on how storage is billed, refer to Editions and Add-Ons.
## Independent scaling
Because the nodes running CockroachDB are stateless and separated from the storage layer, storage now scales independently.
## Durability and security
Plenum provides redundant storage across availability zones in a region. Data is encrypted at rest with its own keys, so clusters sharing Plenum's storage service are cryptographically isolated from one another.
## Demo video
For a demonstration of how to use Cockroach Plenum and cluster virtualization, watch the following video:
## See also
* Editions and Add-Ons
* Create a Cluster
* Mission Critical clusters