This topic describes the differences between Apsara File Storage NAS, Object Storage Service (OSS), and Elastic Block Storage (EBS) to help you choose Apsara File Storage NAS in applicable scenarios.

NAS provides simple, scalable, and shared file storage. You can integrate NAS with Elastic Compute Service (ECS) to construct your business system. You need to consider multiple factors when you choose one service from NAS, OSS, and EBS to deploy your applications. To help you make an informed choice, this topic describes the differences between the three services in the following part of this topic.

Topology
Storage service Latency Throughput Access mode
NAS Low latency (milliseconds) Hundreds of gigabits per second Thousands of ECS instances concurrently perform random read/write operations on a NAS file system over POSIX.
Object Storage Service (OSS) Low latency (tens of milliseconds) Hundreds of gigabits per second Millions of clients concurrently access an OSS bucket and perform append operations over the web.
EBS Ultra-low latency (microseconds) Tens of gigabits per second A single ECS instance performs random read/write operations on a block storage device over POSIX.

Differences between Apsara File Storage NAS and OSS

The major difference between Apsara File Storage NAS and OSS is that you can access a NAS file system the same way you access a local file system without modifying an application. NAS provides high throughput and high IOPS, and supports random read/write operations and online modification of files.

Compared with the directory tree hierarchy of NAS, OSS stores objects in flat files, which are accessed by using RESTful APIs. OSS does not support random read/write operations. OSS is applicable to the upload, download, and distribution of huge volumes of data over the Internet.

Differences between NAS and EBS

The major difference between NAS and EBS is that NAS provides high throughput and supports simultaneous access from thousands of ECS instances.

EBS devices are bare disks. After an EBS device is attached to an ECS instance, you must format the file system of the device into a file system such as ext3, ext4, or NTFS before you can access the files stored on the device. EBS is applicable to I/O-intensive applications that require high performance and low latency, such as Online Transactional Processing (OLTP) and NoSQL databases. However, the maximum storage capacity of an EBS device is 32 TB and is unscalable. EBS devices must work with cluster management software such as Oracle Real Application Clusters (Oracle RAC) and Windows Server Failover Clustering (WSFC) to provide shared access. Therefore, each EBS device provides high-performance and low-latency storage service for only one ECS instance.