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

Apsara File Storage NAS provides simple, scalable, elastic, and shared file storage. You can combine this service with Elastic Compute Service (ECS) to construct your business system. You need to consider multiple factors when you deploy your applications and choose among Apsara File Storage NAS, OSS, and EBS for your applications. To help you make an informed selection, the following describes the differences between the three services.

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Differences between Apsara File Storage NAS and OSS

The major difference between Apsara File Storage NAS and OSS is that you can access an Apsara File Storage NAS file system in the same way as you access a local file system without modifying an application. Apsara File Storage 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 Apsara File Storage NAS, OSS adopts a different storage structure where objects are stored in flat files and are accessed through RESTful APIs. OSS does not support random read/write operations. It is mainly applicable to the upload, download, and distribution of massive volumes of data over the Internet.

Differences between Apsara File Storage NAS and EBS

The major difference between Apsara File Storage NAS and EBS is that Apsara File Storage NAS provides high throughput and supports simultaneous access by 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 accessing 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 storage capacity of an EBS device is 32 TB and is unscalable. It 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 usually provides high-performance and low-latency storage service for only one ECS instance.

Storage service Latency Throughput Access mode
Apsara File Storage NAS Low latency, in milliseconds Hundreds of Gbps Thousands of ECS instances perform concurrent random read/write operations on an Apsara File Storage NAS file system through POSIX.
OSS Relatively low latency, in tens of milliseconds Hundreds of Gbps Millions of clients access and perform concurrent append operations on an OSS bucket on the web.
EBS Ultra-low latency, in microseconds Tens of Gbps A single ECS instance performs random read/write operations on a block storage device through POSIX.