Wiki source code of Ceph

Version 2.1 by Jonas Jelten on 2024/08/23 13:48
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1 We offer [Ceph](https://ceph.io) as a scalable and fast way to obtain storage for your needs.
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3 {{toc/}}
4
5 ## How does it work?
6
7 The gist how Ceph works for you:
8 We have many servers with SSDs or HDDs, each bought by one organization unit such as a chair. Data is spread accross all servers, and each organization unit gets as much storage space as they bought in servers.
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10 You can access the storage mainly via RBD (RADOS block device), which is a device behaving like a local disk (USB stick, SSD, ...), but actually stores and retrieves data from the cluster in our data centre.
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12 ## RBD acquisition
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14 An RBD is a **storage device** you can use in your servers to store data in our Ceph cluster. It either uses **HDD** or **SSD** storage (cheaper vs faster).
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16 For evaluation purposes, you can get small amounts of storage directly.
17 Otherwise, you can get as much space as you are entitled to.
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19 Each RBD is stored in a "namespace", which **restricts access** to it. You can have multiple RBDs in the same namespace.
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21 The name of an RBD is `ORG-name/namespacename/rbdname.`
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23 To request the creation (or extension) of an RBD, write to [[support@ito.cit.tum.de|mailto:support@ito.cit.tum.de]] specifying **name**, **size**, **namespace** and **HDD/SSD**.
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25 You will get back a secret **keyring** to access the namespace.
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27 ## RBD mapping
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29 In order to "use" an RBD in your server, you need to "map" it.
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31 You should have ready the name and keyring of the RBD.
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33 * Please install `ceph-common`, at least in version 15.
34 * It contains a tool named `rbdmap`, which can (oh wonder) map your RBD.
35 * Edit /etc/ceph/rbdmap to add your RBD in a line
36 * it has the format: `rbdname name=keyringname,options=...`
37 * `ORG-name/namespacename/rbdname name=client.ORG.rbd.namespacename,options='queue_depth=1024'`
38 * Place the keyring file in /etc/ceph/
39 * Filename: `ceph.client.ORG.rbd.namespacename.keyring`
40 * Permissions: 700
41 * Owner: root
42 * Content: the client identifier and 28 byte key in base64 encoding.
43 * [client.ORG.rbd.namespacename]
44 key = ASD+OdlsdoTQJxFFljfCDEf/ASDFlYIbEbZatg==
45
46 ## RBD formatting
47
48 Now that you have mapped your RBD, we can create file system structures on it.