# Description of the Data Storage Infrastructure
URL: /en/docs/introduction/description

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## title: Description of the Data Storage Infrastructure

The data centers operated by CESNET are based on object storage technology utilizing Ceph, as described below. These data centers are located exclusively within the Czech Republic, meaning all your data remains within the country. The distributed model of these data centers enhances data redundancy through the use of geographical replicas. This approach ensures that your data is protected against media failures, natural disasters, or user errors. Another advantage is that you can use the data center closest to your location for improved efficiency.

![infrastructure](/img/data-care/infrastructure/mapcr-new-transparent.png)

**CEPH** - Ceph is a software solution designed to provide object storage. Unlike traditional file-oriented data storage, object storage stores data as objects rather than data blocks. Metadata is directly associated with each object, eliminating the hierarchical structure used in conventional data storage systems. Instead, all data is stored in a flat namespace, making it highly scalable. Ceph is an open-source system that includes an object store, block store, and distributed file system. It supports object access (RADOS), exported block devices, and file access. Data stored in Ceph is replicated across multiple nodes based on a defined replication policy.

## Datacenters

Cesnet Data Storage Department currently operates the following datacenters:

| Data Center               | Type | Loacation     | Raw capacity PB | In operation since | Status | S3 Endpoint Address           |
| :------------------------ | :--- | :------------ | :-------------- | :----------------- | :----- | :---------------------------- |
| [CL1](#cl1-jihlava)       | CEPH | Jihlava       | 25.394          | 2025               | online | `https://s3.cl1.du.cesnet.cz` |
| [CL2](#cl2-plzeň)         | CEPH | Plzeň         | 25.433          | 2020               | online | `https://s3.cl2.du.cesnet.cz` |
| [CL3](#cl3-ostrava)       | CEPH | Ostrava       | 33.673          | 2021               | online | `https://s3.cl3.du.cesnet.cz` |
| [CL4](#cl4-brno)          | CEPH | Brno          | 26.607          | 2022               | online | `https://s3.cl4.du.cesnet.cz` |
| [CL5](#cl5-dolní-břežany) | CEPH | Dolní Břežany | 25.536          | 2023               | online | `https://s3.cl5.du.cesnet.cz` |

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### CL1 Jihlava

Object storage CL1 (modernised in 2025) is based on Ceph technology and consists of 34 storage servers, each equipped with 32 disks, totaling a capacity of 25.394 PB. Data access is provided by ten front-end servers.

Available services: [RBD](../object-storage-rbd/rbd-service) and [S3](../object-storage-s3/s3-service)

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### CL2 Plzeň

Object storage CL2 is based on Ceph technology and consists of 33 storage servers, each with 48 HDDs (16 TB each), totaling a capacity of 25.43 PB. Data access is provided by five front-end servers.

Available services: [RBD](../object-storage-rbd/rbd-service) and [S3](../object-storage-s3/s3-service)

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### CL3 Ostrava

Object storage CL3 is based on Ceph technology and consists of 74 storage servers, each with 24 HDDs, totaling a capacity of 33.67 PB. Data access is provided by five front-end servers.

Available services: [RBD](../object-storage-rbd/rbd-service) and [S3](../object-storage-s3/s3-service)

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### CL4 Brno

Object storage CL4 is based on Ceph technology and consists of 57 storage servers, each with 24 HDDs, totaling a capacity of 26.607 PB. Data access is provided by five front-end servers and nine aplications servers.

Available services: [RBD](../object-storage-rbd/rbd-service) and [S3](../object-storage-s3/s3-service)

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### CL5 Dolní Břežany

Object storage CL5 is based on Ceph technology and consists of 50 storage servers, each with 30 HDDs, totaling a capacity of 25.536 PB. Data access is provided by five front-end servers.

Available services: [RBD](../object-storage-rbd/rbd-service) and [S3](../object-storage-s3/s3-service)

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## Decomissioned and Historical Datacenters

| Data Center | Type | Loacation | Raw capacity PB | In operation since | Status           |
| :---------- | :--- | :-------- | :-------------- | :----------------- | :--------------- |
| DU1         | HSM  | Plzeň     | 3.6             | 2011               | decomissioned    |
| DU2         | HSM  | Jihlava   | 7.209           | 2013               | decomissioned    |
| DU3         | HSM  | Brno      | 3.52            | 2013               | decomissioned    |
| DU4         | HSM  | Ostrava   | 23.341          | 2017               | offline          |
| DU5         | RAID | Jihlava   | 9.36            | 2019               | decomissioned    |
| CL1         | CEPH | Jihlava   | 10.56           | 2019               | replaced in 2025 |
