This topic provides answers to some frequently asked questions (FAQ) about Apsara File Storage NAS.

What is NAS?

Apsara File Storage NAS is a distributed file system that provides shared access, scalability, high reliability, and high performance. NAS supports POSIX-based APIs. A NAS file system can be mounted on thousands of compute nodes for shared storage. The compute nodes include Elastic Compute Service (ECS) instances, ECS Bare Metal instances, Container Service for Kubernetes (ACK) clusters, elastic container instances (ECIs), Batch Compute instances, Elastic High Performance Computing (E-HPC) clusters, and Machine Learning Platform for AI models. You can mount NAS file systems to provide high-performance shared storage for these compute resources. You can seamlessly migrate your business systems to Alibaba Cloud without the need to modify your application code.

What are the use scenarios of NAS?

NAS provides file sharing solutions for ECS instances in the following scenarios:
  • To deploy web servers by attaching multiple ECS instances to a Server Load Balancer (SLB) instance, a shared storage space is required for the ECS instances to share data.
  • To process and analyze log data of multiple ECS instances in a centralized manner, a shared storage space is required for the ECS instances to store the log data.
  • To share files among business groups within an enterprise, a shared storage space is required to store data.

How can data be dumped to an IA storage medium?

After you enable the lifecycle management feature and create a lifecycle policy, data that meets the rule specified in the lifecycle policy is automatically dumped to an Infrequent Access (IA) storage medium. For example, when you create a lifecycle policy for a directory, you set the Management Rule parameter to "More than 14 days from the most recent access". If a file in the directory is not accessed for 14 days, the file is automatically dumped to an IA storage medium.

What protocols are supported by NAS?

NAS supports the following protocols:
  • NFSv3 and NFSv4.0.
  • SMB 2.1 and later versions. NAS also supports operating systems including Windows 7, Windows Server 2008 R2, and later versions. However, NAS does not support Windows Vista, Windows Server 2008, or earlier versions.

Which protocol can I select for a NAS file system?

We recommend that you select a protocol for the file system based on your business requirements.
  • If you want to share files among Linux clients, we recommend that you create a Network File System (NFS) file system.
  • If you want to share files among Windows clients, we recommend that you create a Server Message Block (SMB) file system.
  • If you want to share files between Linux clients and Windows clients, we recommend that you create an SMB file system.

What are the limits of NAS file systems?

  • Each Alibaba Cloud account can create a maximum of 20 General-purpose NAS file systems and 200 Extreme NAS file systems in a region.
  • The maximum capacity of a Capacity NAS file system is 10 PiB. The maximum capacity of a Performance NAS file system is 1 PiB. The maximum capacity of an Extreme NAS file system is 256 TiB.
  • A General-purpose NAS file system can contain a maximum of 1 billion files. An Extreme NAS file system can contain a maximum of 0.5 billion files.

For more information, see Limits.

How many compute nodes share access to files? How many file systems do I need to create?

You need to create only one file system. You can mount up to 1,000 compute nodes on the file system at the same time. For more information about the limits on file systems, see Limits.

When you create a file system, we recommend that you select the region of the Elastic Compute Service (ECS) instance on which you want to mount the file system. Otherwise, the ECS instance cannot access the NAS file system. You can use Cloud Enterprise Network (CEN) to mount a file system across regions. However, a cross-region mount degrades the data transfer performance of the file system. For more information, see Create a file system.

Does NAS support active-active and multi-zone scenarios?

No, NAS does not support active-active or multi-zone scenarios.

If you want to back up data stored in a General-purpose NAS file system, you can enable the data backup and recycle bin features. If you want to back up data stored in an Extreme NAS file system, you can enable the data backup and snapshot features. For more information, see Back up and restore files, Recycle bin, and Manage snapshots.