Compute_Cloud_Services_#3.docx

Image Management Service ======================== Why IMS? ======== - **Convenient**: You can create a private from an ECS or external image file, or batch-create ECSs from an image. - **Flexible**: You can manage images through the management console or using APIs. - **Centralized...

Image Management Service ======================== Why IMS? ======== - **Convenient**: You can create a private from an ECS or external image file, or batch-create ECSs from an image. - **Flexible**: You can manage images through the management console or using APIs. - **Centralized**: IMS provides a self-service platform to simplify image management and maintenance. - **Secure**: Public images come with multiple mainstream OSs, such as Windows Server, Ubuntu, and CentOS, which have been thoroughly tested to provide secure and stable services. Image Types =========== - **Public image**: A public image is a standard image provided by the cloud platform and is available to all users. It contains an OS and various preinstalled public applications. If a public image does not contain the application environment or software you need, you can use a public image to create an ECS and then install the software you need. Public images include the following OSs to choose from: Windows, CentOS, Debian, openSUSE, Fedora, Ubuntu, EulerOS, and CoreOS. When you use certain public images, the system recommends the Host Security Service (HSS) and server monitoring. HSS supports two-factor authentication for logins, defense against account cracking, and weak password detection to protect your ECSs against brute-force attacks. - **Private image**: A private image is only available to the user who created it. It contains an OS, service data, preinstalled public applications, and custom applications that the image creator added. A private image can be a system disk image, data disk image, or full-ECS image. - A system disk image contains an OS and pre-installed software for various services. You can use a system disk image to create ECSs and migrate your services to the cloud. - A data disk image contains only service data. You can use a data disk image to create EVS disks and use them to migrate your service data to the cloud. - A full-ECS image contains an OS, pre-installed software, and service data. - **Shared image**: A shared image is a private image another user has shared with you. - **Marketplace image**: A Marketplace image is a third-party image published in the Marketplace. It has an OS, application environment, and software pre-installed. You can use these images to deploy websites and application development environments in just a few clicks. No additional configuration is required. Marketplace images are provided by service providers who have extensive experience configuring and maintaining cloud servers. All the images are thoroughly tested and have been approved by HUAWEI CLOUD before being published. Scenarios ========= Deploying a Specific Software Environment ========================================= Backing Up Server Environments ============================== Other Compute Services ====================== Why AS? ======= - **Automatic resource adjustment**: AS adds ECS instances and increases bandwidth for your applications when the access volume increases and reduces unneeded resources when the access volume drops, ensuring system stability. - **Enhanced cost management**: AS enables you to use instances and bandwidth on demand by automatically adjusting system resources, so utilization goes up and costs go down. - **Improved availability**: AS ensures there are always enough resources deployed for your applications. When working with ELB, AS automatically associates a load balancing listener with any instances newly added to the AS group. Then, ELB automatically distributes access traffic to all instances in the AS group through the listener, which improves system availability. - **High fault tolerance**: AS monitors the status of instances in an AS group, and replaces any unhealthy instances it detects. AS Architecture =============== - **Scaling control**: You can specify thresholds and schedule when different scaling actions are taken. AS will trigger scaling actions on a repeating schedule, at a specific time, or when configured thresholds are reached. - **Policy configuration**: You can configure alarm-based, scheduled, and periodic policies as needed. - **Alarm-based**: You can configure alarm metrics such as vCPU, memory, disk, and inbound traffic. - Scheduled: You can schedule actions to be taken at a specific time. - **Periodic**: You can configure scaling actions to be taken at scheduled intervals, at a specific time, or within a particular time range. - When Cloud Eye generates an alarm for a monitoring metric, for example, CPU usage, AS automatically increases or decreases the number of instances in the AS group or the EIP bandwidth. - When the configured triggering time arrives, a scaling action is triggered to increase or decrease the number of ECS instances or the bandwidth. Scenarios ========= - **E-commerce**: During big promotions, E-commerce websites need more resources. AS automatically scales out ECS instances and bandwidth within minutes to ensure that promotions go smoothly. - **Heavy-traffic portals**: Service load changes are difficult to predict for heavy-traffic web portals. AS dynamically scales in or out of ECS instances based on monitored ECS metrics, such as vCPU usage and memory usage. AS Basic Concepts ================= - **AS group**: An AS group consists of a collection of instances and AS policies that have similar attributes and apply to the same scenario. It is the basis for enabling or disabling AS policies and performing scaling actions. - **AS configuration**: An AS configuration is a template specifying specifications for the instances to be added to an AS group. The specifications include the ECS type, vCPUs, memory, image, disk, and login mode. - **AS policy**: An AS policy can trigger scaling actions to adjust the number of instances in an AS group. An AS policy defines the condition to trigger a scaling action and the operations to be performed. When the triggering condition is met, the system automatically triggers a scaling action. - **Scaling action**: A scaling action adds instances to or removes instances from an AS group. It ensures that the number of instances in an application system is the same as the expected number of instances by adding or removing instances when the triggering condition is met, which improves system stability. - **Cooldown period**: To prevent an alarm policy from being repeatedly triggered for the same event, we use a cooldown period. The cooldown period specifies how long any alarm-triggered scaling action will be disallowed after a previous scaling action is complete. The cooldown period is not used for scheduled or periodic scaling actions. - **Bandwidth scaling**: AS automatically adjusts a bandwidth based on the configured bandwidth scaling policy. AS can only adjust the bandwidth of pay-per-use EIPs and shared bandwidths. It cannot adjust the bandwidth of yearly/monthly EIPs.