<table border="1" cellpadding="0" cellspacing="0"> <tbody> <tr> <td style="background-color:#ededed; vertical-align:top"> <p><strong>Name</strong></p> </td> <td style="background-color:#ededed; vertical-align:top"> <p><strong>Description</strong></p> </td> </tr> <tr> <td style="vertical-align:top"> <p>Region</p> </td> <td style="vertical-align:top"> <p>The location of instances. One region contains multiple availability zones.</p> <p>Ping An Cloud DDS creates remote disaster recovery instances in different regions.</p> </td> </tr> <tr> <td style="vertical-align:top"> <p>Availability Zone</p> </td> <td style="vertical-align:top"> <p>A physical area with an isolated power supply and network. One availability zone contains one or more data centers.</p> </td> </tr> <tr> <td style="vertical-align:top"> <p>Primary Availability Zone</p> </td> <td style="vertical-align:top"> <p>The application&rsquo;s access to the region where a DDS instance is located (i.e. a specified availability zone when a DDS is created) is readable and writable.</p> <p>You are advised to create a DDS instance and an ESC cloud host where your application is located in the same availability zone.</p> </td> </tr> <tr> <td style="vertical-align:top"> <p>Replica Set</p> </td> <td style="vertical-align:top"> <p>It consists of multiple DDS instances with the same data and contains multiple data nodes and arbitration nodes.</p> <p><img src="https://obs-cn-shanghai.yun.pingan.com/pcp-portal/20202108135848-1e2daa969841.png" style="height:20px; margin:0px; width:80px" />:</p> <ul> <li>In the same replica set, only one data node becomes primary node and other data nodes are secondary nodes.</li> <li>Data nodes are independent of each other, resource-isolated, and deployed in different physical servers.</li> </ul> </td> </tr> <tr> <td style="vertical-align:top"> <p>General Instance</p> </td> <td style="vertical-align:top"> <p>Create a DDS instance in a specified region. In <a href="http://pinganyun.com/ssr/help/database/mongodb/index.Architecture" target="_blank">3+0 architecture</a>, the system will create one general instance primary node and two general instances secondary nodes. In <a href="http://pinganyun.com/ssr/help/database/mongodb/index.Architecture" target="_blank">2+1 architecture</a>, the system creates one general instance primary node, one general instance secondary node, and one citywide disaster recovery instance. General instance primary node is readable and writable and accessible to application by default.</p> </td> </tr> <tr> <td style="vertical-align:top"> <p>Citywide Disaster Recovery Instance</p> </td> <td style="vertical-align:top"> <p>To improve high availability of the system, if there are two or more availability zones in one region when you create a DDS instance, Ping An Cloud will automatically create a citywide disaster recovery instance by default.</p> <p><img src="https://obs-cn-shanghai.yun.pingan.com/pcp-portal/20202108135848-1e2daa969841.png" style="height:20px; margin:0px; width:80px" />:</p> <ul> <li>A maximum of one citywide disaster recovery can be created.</li> <li>There may be delays in data synchronization between general instances and citywide disaster recovery instances.</li> </ul> </td> </tr> <tr> <td style="vertical-align:top"> <p>Remote Disaster Recovery Instance</p> </td> <td style="vertical-align:top"> <p>When the region where a general instance is located cannot be connected, remote disaster recovery instance can be used to ensure high availability of business.</p> <p><img src="https://obs-cn-shanghai.yun.pingan.com/pcp-portal/20202108135848-1e2daa969841.png" style="height:20px; margin:0px; width:80px" />:</p> <ul> <li>There is only one remote disaster recovery instance.</li> <li>There may be delays in data synchronization between general instances and remote disaster recovery instances.</li> <li>The remote disaster recovery instance is used only for remote disaster recovery and disaster recovery drills. It does not guarantee the availability and performance of the remote disaster recovery instance and is not used for read-only access of daily business.</li> </ul> </td> </tr> <tr> <td style="vertical-align:top"> <p>Storage Specifications</p> </td> <td style="vertical-align:top"> <p>When you create a DDS instance, you can select storage size.</p> <p>Include DDS instances, storage space for indexes and space for operating DDS instances such as storage spaces for system database, Journal, Oplog Collection, and Syslog.</p> </td> </tr> <tr> <td style="vertical-align:top"> <p>Computing Specifications</p> </td> <td style="vertical-align:top"> <p>When you create a DDS instance, you can select CPU and memory size.</p> <p>CPU represents the limit of usable computing capabilities. Memory represents the limit of usable memory.</p> </td> </tr> <tr> <td style="vertical-align:top"> <p>Temporary Recovery Instance</p> </td> <td style="vertical-align:top"> <p>In the process of restoring backup in database, Ping An Cloud DDS instance will create a temporary recovery instance in the region where a general instance is located. For more information, see <a href="http://pinganyun.com/ssr/help/database/mongodb/Manual.Backup_and_Restore.Restore" target="_blank">Backup Restoration</a>.</p> </td> </tr> </tbody> </table> <p>&nbsp;</p>