Cloud-specific threshold criteria and proactive measures taken when a failure occurs

In this article, the author describes the cloud-specific threshold criteria and scenarios in which proactive measures are taken when a failure occurs.

Threshold performance is the sum of all threshold criteria based on critical cloud components. Cloud threshold performance plays a key role in determining whether a cloud service can be executed under the service availability level specified in the external http://www.aliyun.com/zixun/aggregation/14189.html > Service Level Agreement (SLA).

To ensure consensus on the understanding of threshold standard definitions, a threshold policy standard should be elaborated to outline what cloud computing services computers and vendors should do, while saving a lot of management time for vendors.

Key cloud components to consider when developing threshold standards are:

Resource thresholds: Ensure that resource consumption for applications in the cloud is dynamically balanced within or equal to the threshold level. User thresholds: Ensure that the number of concurrent access applications to the user reaches the maximum limit specified by the vendor in the user's license, below or equal to the threshold level. Data request thresholds: Ensure that all data requests sent to the application, below or equal to the threshold level, are processed in a timely manner. Response thresholds: Ensures that applications respond in a timely manner to user or data requests that are below or equal to the threshold level. The threshold at which an instance is replicated: A service instance replication (or redundancy) that ensures that a host failure is protected within an acceptable threshold level. The maximum value is determined by the availability of resources. Virtual machine Thresholds: Ensure that the number of virtual machines running on the same host is below or equal to the threshold level. Packet switched Network Latency threshold: Ensures that packets are sent to the destination and the delay to return to the external network is less than or equal to the threshold level. Latency includes queued delays to hold multiple packets from different sources.

The first three items have been introduced in previous articles.

Each threshold criterion is determined primarily by the following:

What types of cloud services are hosted by

vendors: Software as a service (SaaS), platform as a service (PaaS) or infrastructure as a service (IaaS). How cloud services users control the operating system, hardware, and software. As well as the type of industry the user represents is broad, such as retail, energy and utilities, financial markets, health care or petrochemicals.

In order to meet the user's requirements for testing threshold standards, all vendors should provide users with copies of these standards. Before renting or buying a cloud service type, the vendor should encourage users to ask questions that may need to be resolved or negotiated.

The impact of user control on threshold standards

The following are the SaaS factors that affect threshold standards.

SaaS User: The only control that an end user has is an application that accesses a vendor from a desktop, notebook, or mobile device. User cannot set threshold level.

SaaS Vendors: The vendor should at least control the operating system, hardware, network infrastructure, application updates, and patches. The vendor sets the level of user, data request, resource, and response thresholds, and restricts negotiation with the user on these threshold levels.

Next comes the PaaS factor that affects the threshold criteria.

PaaS developers: Developers control all applications created and hosted by independent software vendors, start-ups, or large business units throughout the business lifecycle. That is, developers build, deploy, and run custom retail management applications, and manage upgrades and fixes for all the features of the application. As part of the lifecycle, developers use spreadsheets, word processing software, backups, billing, payroll processing, and invoices.

Developers who negotiate with vendors set the level of user, resource, response, and data request thresholds to check application performance on the PaaS. Developers can change the threshold level of each SaaS application on a PAAs to meet SaaS user requirements as a PAAs public user.

PaaS Vendors: The vendor controls at least the operating system, hardware, network infrastructure, and resource management. Vendors have flexibility in negotiating threshold levels with developers.

The following are the IaaS factors that affect threshold standards.

IaaS Infrastructure and network experts: Experts control the operating system, network devices, and deploy applications at the virtual machine level. Infrastructure experts can scale or shrink virtual servers or storage area blocks proportionally. The expert sets the virtual machine and network latency threshold levels.

IaaS Vendor: The supplier controls at least the infrastructure of the traditional computing resources in the cloud environment. They build or upgrade the infrastructure to provide better performing virtual machines. Vendors have flexibility in negotiating threshold levels with developers.