What is available zone？
The available zone is a geographical area (usually an independent physical computer room) in the same service area where the power and network are independent of each other, so that the independence of the available zone can be guaranteed. There are multiple available zones in a region, and a failure of an available zone will not affect other available zones in the same region, and the available zones can be accessed through the intranet.
What is Virtual Private Cloud？
Virtual private cloud provides you with a completely isolated network environment in a logical way. You can define subnets in VPC that are indistinguishable from traditional networks. VPC also provides network services such as elastic IP, security groups, bandwidth, and VPN, etc.
What is image？
An image is an operating system template composed of an operating system, pre-installed public applications, and user private applications, which is convenient for users to quickly create cloud hosts.
What is Public Image？
Provide common standard operating system images visible to all users, including operating systems and pre-installed public applications. Please configure the application environment or related software according to your situation.
What is Image Market？
Provides images of pre-installed operating systems, application environments, and other software. By using the mirror market, fast one-click deployment in environment can be achieved.
What is Security Group？
A security group is a logical group composed of cloud hosts in the same region that have the same security requirements and trust each other. After the creation of security group, users can define various access rules within the security group. When the cloud host joins the security group, it is protected by these access rules. The default rule of the security group is to pass all data packets in the outbound direction, and the cloud hosts in the security group can access each other without adding rules.
What is Elastic IP？
An elastic IP address is an independently applied public IP address. You can dynamically bind an elastic IP to an elastic cloud host so that it can communicate with the Internet.
What is Cloud Hard Disk？
Common of cloud hard disks used by cloud hosts are listed below:
² Regular IO：Provides SATA type storage. The maximum IOPS of this type of cloud hard disk is 1000, which is suitable for application scenarios with large capacity requirement, medium read and write speed, and few transaction processing, such as daily office applications or small-scale tests in enterprises.
² High IO： Provides SAS type storage. The maximum IOPS of this type of cloud hard disk can reach 3000, and the minimum read and write latency is 1 ms. It is suitable for mainstream high-performance and high-reliability application scenarios, such as enterprise applications, large-scale development and testing, and web server logs.
² Ultra High IO：Provide SSD type storage. The maximum IOPS of this type of cloud hard disk can reach 20000, and the minimum read and write latency is 1 ms. It is suitable for ultra-high IO and ultra-large bandwidth read-write-intensive application scenarios, such as high-performance computing applications. It can be deployed distributed file systems, various NoSQL/relational databases , or I/O-intensive application scenarios.
² VBD Type：When you create a cloud hard disk through the control center, the disk mode of the cloud hard disk is VBD type by default. VBD type cloud hard drives only support simple SCSI read and write commands.
² SCSI Type：You can create a SCSI cloud hard disk through the control center. This type of cloud hard disk supports transparent transmission of SCSI commands, allowing the cloud host operating system to directly access the underlying storage medium. In addition to simple SCSI read and write commands, SCSI cloud hard drives can also support more advanced SCSI commands.
