Will I Lose My Disk Data If I Reinstall ECS OS, Change the OS, or Change the ECS Specifications?

**Table 1** Impact
Item	OS Reinstallation	OS Change	Specifications Modification
Application scenario	Initialize an ECS. The ECS OS remains unchanged after OS change.	Change the OS of an ECS by changing its image. For details about OS change constraints, see Changing the OS.	Change ECS specifications, such as increasing the number of vCPUs or adding memory, to meet your service requirements.
Billing	OS reinstallation is free of charge. The ECS price remains unchanged.	OS change is free of charge. However, you will be billed based on your new image type after OS change. .	Modifying ECS specifications is free of charge. However, you will be billed based on the new specifications after modification.
IP address	The private IP address, EIP, and MAC address remain unchanged.	The private IP address, EIP, and MAC address remain unchanged.	The private IP address, EIP, and MAC address remain unchanged.
System disk	Reinstalling OS will clear the data in all partitions of the ECS system disk. Back up data before reinstalling the OS.	Changing OS will clear the data in all partitions of the ECS system disk. Back up data before changing the OS.	No impact on system disk.
Data disk	No impact on data disk.	No impact on data disk	No impact on data disk.
Backup	Back up data before reinstalling the OS to prevent data loss.	Back up data before changing the OS to prevent data loss.	Create a system disk snapshot before modifying ECS specifications to prevent data loss.