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Applies to SUSE Enterprise Storage 5.5 (SES 5 & SES 5.5)

Part II Operating a Cluster Edit source

2 Introduction

In this part of the manual you will learn how to start or stop Ceph services, monitor a cluster's state, use and modify CRUSH Maps, or manage storage pools.

3 Operating Ceph Services

You can operate Ceph services either using systemd, or using DeepSea.

4 Determining Cluster State

When you have a running cluster, you may use the ceph tool to monitor it. Determining the cluster state typically involves checking the status of Ceph OSDs, Ceph Monitors, placement groups and Metadata Servers.

5 Monitoring and Alerting

By default, DeepSea deploys a monitoring and alerting stack on the Salt master. It consists of the following components:

6 Authentication with cephx

To identify clients and protect against man-in-the-middle attacks, Ceph provides its cephx authentication system. Clients in this context are either human users—such as the admin user—or Ceph-related services/daemons, for example OSDs, monitors, or Object Gateways.

7 Stored Data Management

The CRUSH algorithm determines how to store and retrieve data by computing data storage locations. CRUSH empowers Ceph clients to communicate with OSDs directly rather than through a centralized server or broker. With an algorithmically determined method of storing and retrieving data, Ceph avoids a…

8 Managing Storage Pools

Ceph stores data within pools. Pools are logical groups for storing objects. When you first deploy a cluster without creating a pool, Ceph uses the default pools for storing data. The following important highlights relate to Ceph pools:

9 RADOS Block Device

A block is a sequence of bytes, for example a 4MB block of data. Block-based storage interfaces are the most common way to store data with rotating media, such as hard disks, CDs, floppy disks. The ubiquity of block device interfaces makes a virtual block device an ideal candidate to interact with a…

10 Erasure Coded Pools

Ceph provides an alternative to the normal replication of data in pools, called erasure or erasure coded pool. Erasure pools do not provide all functionality of replicated pools (for example it cannot store metadata for RBD pools), but require less raw storage. A default erasure pool capable of stor…

11 Cache Tiering

A cache tier is an additional storage layer implemented between the client and the standard storage. It is designed to speed up access to pools stored on slow hard disks and erasure coded pools.

12 Ceph Cluster Configuration

This chapter provides a list of important Ceph cluster settings and their description. The settings are sorted by topic.

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