This topic provides answers to some frequently asked questions (FAQ) about Apsara File Storage NAS (NAS).
What is NAS?
NAS is a distributed file system that provides shared access, scalability, high reliability, and high performance. NAS supports Portable Operating System Interface for UNIX (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 Platform for AI (PAI) 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.
For more information about the use scenarios of NAS, see Scenarios.
Can a NAS file system be mounted on a simple application server?
Yes, but you must ensure the network connectivity between the simple application server and the mount target of the NAS file system.
If you need to mount a NAS file system on a server, we recommend that you use ECS. You must ensure the network connectivity between the ECS instance and the mount target. ECS provides Infrastructure as a Service (IaaS)-level cloud computing services with excellent performance, stability, reliability, and elastic scalability. ECS provides ready-to-use and scalable computing resources, eliminating the need to purchase IT hardware in advance.
How can data be dumped to the IA storage class?
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 the Infrequent Access (IA) storage class. 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 the IA storage class.
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 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 files from a General-purpose NAS file system, Recycle bin, and Manage snapshots.
Can I mount a NAS file system on a compute node that is not provided by Alibaba Cloud?
NAS is a file storage service designed for compute nodes such as ECS instances, E-HPC clusters, and ACK clusters. You cannot mount a NAS file system on a compute node that is not provided by Alibaba Cloud, such as a compute node deployed on Tencent Cloud, an on-premises data center, an on-premises server, or a PC. However, you can mount a NAS file system on a client and then use a virtual private network (VPN) gateway or a network address translation (NAT) gateway to access the NAS file system. For more information, see Access a NAS file system from a data center by using a NAT gateway and Access a NAS file system from a data center by using VPN gateways.
How do I select a NAS file system when I migrate data from another storage medium to the file system?
NAS supports two file system types: General-purpose NAS file systems and Extreme NAS file systems. If you use general file sharing services, we recommend that you use General-purpose NAS file systems. If your services require low latency, we recommend that you use Extreme NAS file systems. For more information, see How do I select file systems?
The storage types of file systems cannot be changed. For more information about the limits on file systems, see Limits.
Can I switch between the storage types or between storage specifications for NAS file systems?
No, the storage types or storage specifications for NAS file systems cannot be mutually switched. However, you can perform the following operations to purchase a new file system, migrate data from the old file system to the new file system, and then switch workloads to the new file system:
Purchase a file system of the required storage type. For more information, see Create a file system.
Migrate data from the old file system to the new file system.
You can use one of the following methods to migrate data:
Use Data Transport to migrate data. For more information, see Migrate data by using Data Transport.
Use the rsync command-line tool to migrate data. For more information, see Migrate data by using the rsync command-line tool.
Use the Robocopy tool to migrate data. For more information, see Migrate data by using the Robocopy tool.
Switch workloads to the new file system. For more information, see Switch workloads to the new file system.
ImportantAfter you switch workloads to the new file system, retain the data that is stored in the original file system for at least one week. If you immediately delete data from the original file system, data loss may occur due to accidental deletion or accidental synchronization.