Performance

Due to Ceph's distributed approach, it can offer unrestrained performance compared with scale-up storage arrays, which typically have to funnel all I/O through a pair of controller heads. Although technology has constantly been providing new faster CPUs and faster network speeds, there is still a limit to the performance you can expect to achieve with just a pair of controllers. With recent advances in flash technology combined with new interfaces such as Non-volatile Memory Express (NVMe), the scale-out nature of Ceph provides a linear increase in CPU and network resource with every added OSD node.

Let us also consider where Ceph is not a good fit for performance, and this is mainly around use cases where extremely low latency is desired. For the very reason that enables Ceph to become a scale-out solution, it also means that low latency performance will suffer. The overhead of software and additional network hops means that latency will tend to be about double that of a traditional storage array and 10 times that of local storage. A thought should be given to selecting the best technology for given performance requirements. That said, a well-designed and tuned Ceph cluster should be able to meet performance requirements in all but the most extreme cases.