创建高可用性副本

在主动/被动配置中，副本设备是主设备的冗余副本。如果主设备发生故障，高可用性模式允许副本作为主设备运行，从而最大限度地减少服务中断。

本文内容

创建高可用性副本
创建 Geo-replication 副本
为 Geo-replication 配置 DNS

创建高可用性副本

在所需平台上设置新的 GitHub Enterprise Server 设备。副本设备应镜像主设备的 CPU、RAM 和存储设置。建议您在独立环境中安装副本设备。底层硬件、软件和网络组件应与主设备的相应部分隔离。如果要使用云提供商，请使用单独的区域或分区。更多信息请参阅“设置 GitHub Enterprise Server 实例”。
在浏览器中，导航到新副本设备的 IP 地址并上传您的 GitHub Enterprise 许可。
设置与主设备密码匹配的管理员密码，然后继续。
单击 Configure as Replica。
在“Add new SSH key”下，输入 SSH 密钥。
单击 Add key，然后单击 Continue。
使用 SSH 连接到副本设备的 IP 地址。
```
$ ssh -p 122 admin@REPLICA IP
```
To generate a key pair for replication, use the ghe-repl-setup command with the primary appliance's IP address and copy the public key that it returns.
```
$ ghe-repl-setup PRIMARY IP
```
To add the public key to the list of authorized keys on the primary appliance, browse to https://PRIMARY-HOSTNAME/setup/settings and add the key you copied from the replica to the list.
To verify the connection to the primary and enable replica mode for the new replica, run ghe-repl-setup again.
```
$ ghe-repl-setup PRIMARY IP
```
要开始复制数据存储，请使用 ghe-repl-start 命令。
```
$ ghe-repl-start
```
**警告：** `ghe-repl-start` 会导致主要服务短暂中断，期间用户可能会看到内部服务器错误。为提供更简便的消息，请在副本节点上运行 `ghe-repl-start` 之前，先在主要节点上运行 `ghe-maintenance -s`，使副本置于维护模式。在复制开始后，使用 `ghe-maintenance -u` 禁用维护模式。
To verify the status of each datastore's replication channel, use the ghe-repl-status command.
```
$ ghe-repl-status
```

创建 Geo-replication 副本

This example configuration uses a primary and two replicas, which are located in three different geographic regions. 由于三个节点可以位于不同网络中，要求所有节点均可从其他所有节点到达。必需的管理端口至少应向其他所有节点开放。 For more information about the port requirements, see "Network Ports."

Create the first replica the same way you would for a standard two node configuration by running ghe-repl-setup on the first replica.
```
(replica1)$ ghe-repl-setup PRIMARY IP(replica1)$ ghe-repl-start
```
Create a second replica and use the ghe-repl-setup --add command. The --add flag prevents it from overwriting the existing replication configuration and adds the new replica to the configuration.
```
(replica2)$ ghe-repl-setup --add PRIMARY IP(replica2)$ ghe-repl-start
```
By default, replicas are configured to the same datacenter. 为数据中心选项设置不同的值，通过这种方式为不同的数据中心配置副本。可以随意设定特定值，只要数值彼此不同即可。 Run the ghe-repl-node command on each node and specify the datacenter.

On the primary:
```
(primary)$ ghe-repl-node --datacenter [PRIMARY DC NAME]
```
On the first replica:
```
(replica1)$ ghe-repl-node --datacenter [FIRST REPLICA DC NAME]
```
On the second replica:
```
(replica2)$ ghe-repl-node --datacenter [SECOND REPLICA DC NAME]
```
Tip: You can set the --datacenter and --active options at the same time.
活动副本节点将存储设备数据的副本并为最终用户请求提供服务。非活动节点将存储设备数据的副本，但无法为最终用户请求提供服务。 Enable active mode using the --active flag or inactive mode using the --inactive flag.

On the first replica:
```
(replica1)$ ghe-repl-node --active
```
On the second replica:
```
(replica2)$ ghe-repl-node --active
```
To apply the configuration, use the ghe-config-apply command on the primary.
```
(primary)$ ghe-config-apply
```

为 Geo-replication 配置 DNS

Configure Geo DNS using the IP addresses of the primary and replica nodes. You can also create a DNS CNAME for the primary node (e.g. primary.github.example.com) to access the primary node via SSH or to back it up via backup-utils.

For testing, you can add entries to the local workstation's hosts file (for example, /etc/hosts). These example entries will resolve requests for HOSTNAME to replica2. 您可以注释不同的行，以特定主机为目标。

# <primary IP>     <em>HOSTNAME</em>
# <replica1 IP>    <em>HOSTNAME</em>
<replica2 IP>    <em>HOSTNAME</em>

创建高可用性副本

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