One, background
Since before the changes had to be replaced because there are business examples, but the data and network synchronization needs to be done, the face of this demand, we are racking their brains, carefully specializes Ali cloud product documentation, and finally solve the problem, here sort out the actual operation, the stepped pit record it.
Second, the business value
Migrate through snapshots and mirroring the way data can be circumvented traditional stop operation, there will be only a short period of ten seconds when unbundling business interruption and rebinding EIP, for the online business is concerned almost no sense of .
Third, the specific operation process
1. Data Migration section
First, we need to cloud disk before ECS instances do snapshots (If you need to transfer all the data, that is the system disk to do a snapshot of the disk system, the data disk data disk that also need to do a snapshot), Ali cloud into the management console, find old examples of ECS
• It should be noted that in order to ensure a snapshot is created, the snapshot is being created, do not modify the state ECS instance, such as stop or restart ECS instance. please wait patiently.
• Also note that when you create a snapshot in "Expired" state of the disk, if the disk has reached the release time expired, the disk will be released, the snapshot creation will also be deleted.
Snapshots can be taken arbitrarily named for easy identification later period, here I give a name for the data migration, the following tags do not control the selection, click OK to start doing after snapshot, of course, is actually a snapshot backup mechanism, so take some time, especially the first snapshot of the full backup, the time required to do with the amount of data on the disk.
When the progress of 100%, the status display illustrates the success of the snapshot has been created, where we can see, the mirror can only be done through the system disk to create a snapshot, click on the back to create a custom image
Note here that, if there is a data disk, you need to be a mirror disk snapshot data disk snapshots on the system together, then select Add just created good data disk snapshots on the line, there is also a note: the size of the data disk snapshots can not exceed 1000G, otherwise Creating unsuccessful.
After the mirror do we return an instance of the interface
As with snapshots, progress is 100%, the state is available, shows that our mirror and do a good job. Then we needed to purchase ECS interface Select the appropriate configuration on the list, select Custom in the Mirror mirror part, just do a good job of mirroring the past may not be real-time synchronization, you need to click the Refresh button, this time there will be that we just do a good job of mirroring
此时我们可以看到，因为我们同步了数据盘快照的信息，所以在选择好镜像的同时，系统自动创建了一个数据盘，大小跟我们创建的快照大小一样，然后我们只需要选好其他配置进行下单就行了，新生产的ECS实例数据跟之前的旧ECS实例一模一样。
完成后从控制台上到系统后台确认一下系统是否确实在新ECS上运行了，如果没问题，就可以继续了。
2. 网络部分迁移
如果原本ECS实例所搭配的就是弹性公网IP，那直接将IP解绑下来绑定到新ECS实例上就行，简单方便。但是如果以前是开通的固定公网IP，此时需要做IP类型转换，相对麻烦很多，具体步骤如下：
a) 将原本的固定带宽转为按量付费（此操作并不是所有账户都有的，如果没有，可以提工单咨询售后看能否操作）
此处有几个注意事项：（这里要仔细看了，千万别踩坑~~）
实例规格停售的不能操作
信用等级不够转不了（信用等级取决于账户情况）
ECS实例转按量过后尽量不要选择停机不收费，不然公网IP会被释放导致IP发生变化影响业务
ECS实例使用的云市场提供的镜像不能进行包年转按量
每个账户每月有最大退款额度的限制。不同等级会员的最大退款额度不同，以转换页面显示为准。当月退款额度超限后不能再操作退款，下月1号自动清零。
b) 点击确认转换，此时实例变为按量模式。然后选择网络和安全组中的公网IP转弹性公网IP，成功过后原本的IP就变成的EIP。注意此过程为不可逆，并且业务会中断。解绑后此时我们就可以将IP从旧ECS实例上解绑下来，绑定到新的ECS实例上。这个过程手慢大约十来秒就搞定，业务就可以重新。
具体来说，首先找到弹性公网IP列表，找到对应的IP,然后解绑
Then click on the binding, select the type of binding instance in ECS, and then select the new ECS corresponding instance, you can complete bound, to this point we have to achieve a seamless migration ECS data and networks.