Ceph is designed to provide a highly fault-tolerant storage system by the scale-out nature of its components. Although no individual component is highly available, when clustered together any component should be able to fail without causing an inability to service client requests. In fact, as your Ceph cluster grows, the failure of individual components should be expected and become part of normal operating conditions. However, Ceph's ability to provide a resilient cluster should not be an invitation to compromise on hardware or design choice. Doing so will likely lead to failure. There are several factors that Ceph assumes your hardware will meet, which are covered later in this chapter.

Unlike RAID where disk rebuilds with larger disks can now stretch into time periods measured in weeks, Ceph will often recover from single disk failures in a matter of hours. With the increasing trend of larger capacity disks, Ceph offers numerous advantages to both the reliability and degraded performance when compared with a traditional storage array.