reset a simple application server - Simple Application Server

Resetting a simple application server allows you to reinstall applications or the operating system to reinitialize the server. You can reset the server by either resetting the current system or replacing it with another image.

Prerequisites

The status of the simple application server is Running or Stopped.

Impact description

Impact item	Description
System disk	After resetting the system, the data on the system disk of the simple application server will be cleared. Please back up your data as needed.
Data disk	Resetting the system will not change or lose the data on the data disk, but please note the following: Resetting the current system For Linux instances: The automatic mounting information configured for the data disks is lost. You must remount file systems to the data disks. The data on the data disks is retained and not affected, but you need to remount the file systems. For Windows instances: No additional operations are required for the data disks. Resetting to another system If you switch between Windows operating systems: Only the system disk of the original instance is replaced, and the data disk of the original instance is not affected. If you switch between Linux operating systems: The system disk of the original instance is replaced, and the data disk of the original instance needs to be remounted for use. If you switch between Windows and Linux operating systems: Not only do you need to replace the system disk of the original instance, but also due to the inability to recognize the file system format, the data disk needs to be reinitialized or separately install software for recognition. For specific operations, see How to use the original data disk after switching between Windows and Linux operating systems?. Important If the image used to replace the operating system contains data from data disks, ensure that no dependency exists between the system disk and data disks in your business, or that operations on the data disks by the changed system disk do not affect your business processes. For example, if your business involves reading and writing data from the system disk to the data disks, switching the operating system may cause exceptions in reading and writing data to the data disks due to changes in the system disk.
Monitoring	After resetting the system, monitoring may become invalid. If monitoring issues occur, you can manually install the CloudMonitor plug-in. Install via remote connection to the server: For specific operations, see Install and uninstall the CloudMonitor plug-in. Install using the command assistant: For specific operations, see Execute commands. You can obtain the command to install CloudMonitor from the common commands in the Execute commands document.
Login credentials	After resetting the system, you need to reset the password and log in with the new password. For specific operations, see Set or reset the server password. If you have bound a key to the current instance, the previously bound key will be automatically unbound during the reinstallation process. After reinstalling the system, you need to rebind the key. For specific operations, see Bind a key pair.
Snapshot	The snapshots created before resetting will be retained, but rollback operations are not supported.

Limits

You cannot reset simple application servers that were created from custom images containing data from data disks.
If your simple application server is deployed outside the Chinese mainland, you cannot switch the operating system of the server between Windows Server and Linux. You cannot use a Windows Server image to reset a Linux simple application server, nor can you use a Linux image to reset a Windows Server simple application server. You can only switch between Windows Server operating systems or between Linux distributions.
If you reset a simple application server by replacing the existing image with a custom image:
- The custom image must be in the same region as the current server.
- You cannot select a custom image containing data from data disks.
- You cannot select a custom image that is created based on the current server.
  
  If you want to restore the original data after you reset the server, you can use a custom image that was created before you reset the server to create a new server.
- If the system disk size of the custom image is larger than that of the simple application server, you cannot directly use the custom image to reset the simple application server.
  
  When the system disk size of the simple application server is greater than or equal to that of the custom image, you can use the custom image to reset the simple application server. To increase the system disk size of your server, you can upgrade the server configuration. For specific operations, see Upgrade Configuration.

Procedure

Log on to the Simple Application Server console.
In the left-side navigation pane, click Servers.
In the server card, select More Actions > Reset System.

Note
You can also click the instance ID on the server card to access the server overview page. At the top menu, click Reset System, or in the Basic Information section, click Reset Image after Image Information.

Reset the server system.

Based on your business requirements, you can reset the system using one of the following methods:

Reset the current system

Reinstall the operating system while retaining the current image.

Parameter	Description
Select Reset Method	Select Reset The Current System.
Advanced Configuration	In the Login Credentials area, choose whether to set a password. Custom Password: Enter the server password and confirm the password. Set After Reset: Do not set the server password after resetting the system. This option is selected by default. Important After resetting the system, you need to reset the password and log in with the new password. For specific operations, see Set or reset the server password. If you have bound a key to the current instance, the previously bound key will be automatically unbound during the reinstallation process. After reinstalling the system, you need to rebind the key. For specific operations, see Bind a key pair.

Reset to another image

Choose from Alibaba Cloud's provided application and system images, or use your own custom images to reinstall the operating system.

Parameter	Description
Select Reset Method	Select Reset The Current System, and choose the corresponding image on the Application Image, System Image, or Custom Image tab.
Advanced Configuration	In the Login Credentials area, choose whether to set a password. Custom Password: Enter the server password and confirm the password. Set After Reset: Do not set the server password after resetting the system. This option is selected by default. Important After resetting the system, you need to reset the password and log in with the new password. For specific operations, see Set or reset the server password. If you have bound a key to the current instance, the previously bound key will be automatically unbound during the reinstallation process. After reinstalling the system, you need to rebind the key. For specific operations, see Bind a key pair.

Click Confirm Reset.
In the dialog box that appears, carefully read the prompt and click OK.
Return to the server list. When the server's status changes from Resetting to Running, the system reset is complete. If the system reset fails, we recommend that you carefully read the content in Limits to check whether the requirements for resetting the system are met:
- If the requirements are met, we recommend that you submit a ticket.
- If the requirements are not met, the simple application server cannot be reset.

What to do next

On the new operating system, you need to redeploy the runtime environment related to your business, such as installing software and libraries (APT, YUM, etc.) and configuring environment variables.
After switching the operating system, the original system disk will be released and the data will be cleared. You can use a snapshot of the original system disk to create a new pay-as-you-go disk and then attach it to the ECS instance to restore data. After data restoration, we recommend that you release the disk in a timely manner. For specific operations, see How to Restore Data from the System Disk Using a Snapshot of the Original System Disk after Changing the System.
How to Use the Original Data Disk after Switching between Windows and Linux Operating Systems?
- After replacing the Linux operating system with a Windows operating system, the Windows operating system cannot recognize Ext3, Ext4, or XFS file systems by default. Based on whether your data disks contain important data, we recommend the following:
  - If your data disks do not contain important data, re-initialize the disks and format them. For specific operations, see Reinitialize the Data Disk and Initialize the Data Disk (Windows).
  - If your data disks contain important data, separately install software for recognition, such as Ext2Read and Ext2Fsd.
- After replacing the Windows operating system with a Linux operating system, the Linux operating system cannot recognize NTFS file systems by default. Based on whether your data disks contain important data, we recommend the following:
  - If your data disks do not contain important data, re-initialize the disks and format them. For specific operations, see Reinitialize the Data Disk and Initialize the Data Disk (Linux).
  - If your data disks contain important data, separately install software for recognition, such as ntfsprogs.
    
    When you use ntfsprogs, run the following commands in sequence to allow the Linux operating system to access the NTFS file systems.
```
yum -y install ntfs-3g
mount -t ntfs-3g <data disk partition name> <mount directory>
```
    Note
    You need to modify <data disk partition name> and <mount directory> based on the actual situation.
    
    For specific operations, see How to Mount an NTFS-Formatted Disk between Linux and Windows Systems?.