Qualitative and quantitative research on the availability of cloud computing (3)

"China Cloud net Exclusive" Chen Whilin, the chief consultant of Cloud Network

3 Reference Design Model

This section presents a number of reference design models (http://www.aliyun.com/zixun/aggregation/16918.html ">reference") based on the discussion of AU and as. and the corresponding availability and convergence ratio are analyzed respectively.

Assume a public cloud system that provides IAAS services; A third party manufacturer deploys PAAs services on the IaaS basis. The SaaS service provider then deploys on the PAAs.

In this section, each SaaS, PAAs, or IaaS module is defined by default as an AU unit.

3.1-Font architecture (Stick architecture)

A font architecture is the simplest deployment model for a cloud service. As shown in Figure 14 and figure 15, a SaaS service is deployed directly on a PAAs service; The PAAs service is deployed on a low-level iaas.

The advantage of a zigzag structure is simplicity and low cost. Its disadvantage is obvious, the existence of multiple single point of failure. For example, between SaaS and PAAs, PAAs and IaaS are a single point of failure. The system does not have fault tolerance.

For IaaS, its maximum deployment availability is: Daiaas = Saiaas

For PAAs, its maximum deployment availability is: Dapaas = Sapaas * Daiaas

For SaaS, its maximum deployment availability is: Dasaas = Sasaas *sapaas * Saiaas

3.2 Diamond Architecture (Diamond architecture)

The Rhombus architecture is a variant of the font architecture, extending the PAAs layer, from a one-font structure to a PAAs for an au to a flattened as containing two AU. As shown in Figure 16 and figure 17, a SaaS service is deployed directly on 2 PAAs services; The 2 PAAs services are deployed on a low-level iaas.

The advantages of Rhombus architecture The reliability of the PAAs layer is improved, and the single point failure of the PAAs layer is removed compared with the one-font architecture. The disadvantage is that the IAAS layer is still a single point of failure. In addition, as the PAAs layer is added, the cost is higher than the one-font architecture.

For IaaS, its maximum deployment availability is: Daiaas = Saiaas

For PAAs, the maximum deployment availability is:

Because DAPaaS1 = DAPaaS2 = Sapaas * Daiaas,

Thus, the availability of the PAAs level as a whole is Dapaas =1-(1-DAPAAS1) * (1-DAPAAS2) =1-(1-sapaas * Saiaas) 2.

For SaaS, its maximum deployment availability is: Dasaas = Sasaas * Dapaas = Sasaas * [N (1-sapaas * Saiaas) 2] = Sasaas * (Sapaas * Saiaas) 2 + 2sasaas*sapaas * Saiaas

3.3-Person font architecture (bone architecture)

The Herringbone architecture is also a variant of the font architecture. The main purpose is to improve the reliability of the IaaS layer. As shown in Figure 18 and figure 19, a SaaS service is deployed directly on a PAAs service; The PAAs service is deployed on a 2-tier IaaS.

The advantage of the herringbone architecture is that the reliability of the IAAS layer is improved, and the single point failure of the IAAS layer is removed compared with the font and diamond architecture. The disadvantage is that the PAAs layer is still a single point of failure. In addition, because of the increase in the IaaS layer of the agency, the need for a font and diamond architecture than the cost of higher.

For IaaS, its maximum deployment availability is: Daiaas =1-(1-DAIASS1) * (1-DAIASS2) =1-(1-saiaas) 2.

For PAAs, its maximum deployment availability is: Dapaas =1-(1-DAPAAS1) * (1-DAPAAS2). Because Dpaas

For SaaS, its maximum deployment availability is: Dasaas = Sasaas * Dapaas = Sasaas * Sapaas * [N (1-saiaas) 2] = Sasaas * Sapaas * SAIaaS2 + 2sasaas*sapaas * S Aiaas

(Responsible editor: Lu Guang)