This topic describes the general limits for the usage of ECS instances and limits that are specific to the installed OS.

General limits

  • After you create an ECS instance, only you have administrator permissions on this instance.
  • You are not allowed to resell or sublicense any bandwidth assigned to your ECS instances without authorization. Failure to comply will result in a suspension or termination of your right to use any portions or all Alibaba Cloud services.
  • Do not use your ECS instances for malicious, fraudulent, or unlawful activities, such as click farming or fraudulent transactions, on e-commerce websites such as Taobao. Failure to comply will result in suspension or termination of your account.
  • Do not uninstall relevant hardware drivers.
  • Do not modify the MAC address of ENIs unless necessary.
  • Do not enable SELinux.
  • An ECS instance with more than 4 GiB RAM must use a 64-bit operating system (OS). The 64-bit OSs currently supported are as follows:
    • Alibaba Cloud Linux 64-bit
    • CoreOS 64-bit
    • CentOS 64-bit
    • Debian 64-bit
    • FreeBSD 64-bit
    • OpenSUSE 64-bit
    • SUSE Linux 64-bit
    • Ubuntu 64-bit
    • Red Hat 64-bit
    • Windows 64-bit

    For the latest available OSs, go to the instance purchase page in the ECS console.

  • To guarantee service continuity, we recommend that you enable automatic startup upon instance boot for relevant software. If service applications are connected to databases, we recommend that you enable automatic re-connection for these service applications.
  • We recommend that you do not upgrade the kernel and the operating system. If you need to upgrade the kernel, see How to avoid Linux instance startup failure after kernel upgrade.

Windows limits

  • Do not stop the built-in AliyunService or shutdownmon.exe process. Otherwise, ECS instances may not be stopped or restarted properly.
  • Do not modify the hostname of the domain controller.
  • We recommend that you do not create custom images by using a virtual machine that acts as a domain controller.
  • Do not rename, delete, or disable the administrator account.
  • We recommend that you do not use the virtual memory if Basic Cloud Disks are used. For ultra disks, standard SSDs, or ESSDs, you can use the virtual memory as needed.
  • Exercise caution when you use the administrator account to resize cloud disks, operate spanned volumes or the registry, and update the system. Failure to comply can result in data loss. For more information, see Resize a cloud disk.
  • Windows 32-bit OSs support up to four CPU cores.
  • Ensure that a minimum of 2 GiB RAM is available when you build a website or deploy a Web environment on a Windows instance. Instances with 1-core CPU and 1 GiB RAM cannot start MySQL.
  • For more information see Select an image.

Linux limits

  • Do not modify the content of the default /etc/issue file on Linux instances. Otherwise, if you create a custom image of such an instance and then use the image to create a new instance, the new instance cannot start properly because the operating system edition cannot be recognized.
  • Do no modify permissions of the directories in the root partition, especially /etc, /sbin, /bin, /boot, /dev, /usr, and /lib. Improper modifications of permissions may cause system errors.
  • Do not rename, delete, or disable the root account.
  • Do not compile the Linux kernel or perform any other operations on it.
  • We recommend that you do not use the swap partition if Basic Cloud Disks are used. However, for ultra disks, standard SSDs, or ESSDs, you can use the swap partition as needed.
  • Exercise caution when you use the root account to run fio, mkfs, or fsck commands or resize cloud disks. Failure to comply can result in data loss.
  • For more information see Select an image.