Alibaba Cloud provides three managed storage services — Object Storage Service (OSS), Elastic Block Storage (EBS), and File Storage NAS (NAS) — each built for a different storage model. Use the decision table below to identify the right service for your workload, then refer to the relevant section for details.
Note: Data availability refers to whether a storage service can respond to data requests. Data durability refers to the annual average expected data loss rate. Performance refers to IOPS or throughput.
Choose a storage service
| If your workload requires... | Use |
|---|---|
| Storing large volumes of unstructured data (images, audio, video, backups, logs) with pay-per-use billing | OSS |
| Low-latency block storage attached to a single ECS instance, such as a database or OS disk | EBS |
| Shared file storage accessible by multiple compute nodes (ECS, E-HPC, ACK) over NFS or SMB | NAS |
Storage model definitions:
| Model | How data is stored | Typical access method |
|---|---|---|
| Object (OSS) | Flat namespace; each item is an object with metadata | HTTP/HTTPS API |
| Block (EBS) | Fixed-size blocks; formatted as a file system by the OS | Directly attached to one ECS instance |
| File (NAS) | Hierarchical directories and files | NFS or SMB protocol; multiple nodes share access |
OSS
OSS is an object storage service for unstructured data — images, audio, video, logs, backups, and similar content. It delivers high durability and availability, and scales automatically without capacity planning.
OSS offers five storage classes that span the full spectrum from hot data to deep archive. Colder classes have lower storage costs but higher retrieval costs and longer restore times.
OSS storage classes
| Storage class | Designed for | Min billable size | Min storage duration | Data access | Retrieval fees |
|---|---|---|---|---|---|
| Standard | Frequently accessed data | — | — | Immediate | None |
| Infrequent Access (IA) | Data accessed once or twice a month | 64 KB | 30 days | Immediate | Yes |
| Archive | Rarely accessed data requiring long-term retention | 64 KB | 60 days | Immediate (if real-time access enabled) or approximately 1 minute after restore | Yes |
| Cold Archive | Cold data with compliance or long-term retention requirements | 64 KB | 180 days | Restore required; time varies by object size and priority | Yes (retrieval + API fees) |
| Deep Cold Archive | Extremely cold data for very long-term storage (tape-equivalent) | 64 KB | 180 days | Restore required; time varies by object size and priority | Yes (retrieval + API fees) |
Typical use cases by class:
Standard: Social networking apps, image and video sharing, large websites, big data analytics
IA: Files accessed monthly — reports, infrequently queried datasets
Archive: Archival data, medical images, scientific datasets, video footage
Cold Archive: Compliance data, raw big data and AI training sets, film and television archives, online education recordings
Deep Cold Archive: Regulatory documents, long-term big data accumulations, media archives previously stored on tape
If you are unsure which class to use, start with Standard and use lifecycle rules to transition objects to colder classes as access frequency drops — for example, transition logs from Standard to IA after 30 days, then to Archive after 90 days. OSS billing is based on actual storage used.
EBS
EBS is a block storage service for Elastic Compute Service (ECS) instances. Format an EBS device and create a file system on it, just as with a physical disk.
EBS provides two device types:
Cloud disks — Distributed block storage built on a triplicate distributed mechanism. Provides low latency, high performance, high durability, and high reliability. Create, resize, and release cloud disks at any time. Use as a system disk or data disk. Billed by provisioned capacity.
Local disks — Physical disks on the host machine running the ECS instance. Suited for workloads that require high I/O performance and cost-effective massive storage, such as distributed databases and big data processing. Provide low latency, high random IOPS, and high throughput. Use only as data disks. Billed by storage capacity. Cannot be purchased separately; billed with the ECS instance using the same billing method.
EBS is billed for the full provisioned capacity regardless of how much you use.
For pricing and available device configurations, see the EBS pricing page.
NAS
NAS is a managed file storage service for compute nodes — including ECS instances, Elastic High-Performance Computing (E-HPC) instances, and Container Service for Kubernetes (ACK) clusters. It is a distributed file system that supports the Network File System (NFS) and Server Message Block (SMB) protocols, and provides shared access, elastic scalability, high reliability, and high performance.
NAS offers three specifications:
| Specification | Storage medium | Bandwidth | Latency | Best for |
|---|---|---|---|---|
| Extreme NAS | All-flash | 150 MB/s – 1,200 MB/s | ~100 microseconds | Latency-sensitive workloads with large numbers of small files |
| General-purpose Performance NAS | SSD | High throughput, high IOPS | Low | Frequent read/write operations with strict latency requirements |
| General-purpose Capacity NAS | SATA HDD | High throughput | Standard | Cost-sensitive workloads where low latency is not required |
The maximum capacity for Extreme NAS is 256 TiB. NAS billing is based on actual storage used.
Summary
| OSS | EBS | NAS | |
|---|---|---|---|
| Storage model | Object | Block | File |
| Billing | Pay per GB used | Pay per GB provisioned | Pay per GB used |
| Shared access | Yes (via HTTP/HTTPS) | No | Yes (NFS / SMB) |
| Primary use | Unstructured data at scale | OS and application disks | Shared workspaces, HPC, containers |
Use OSS as your primary storage service for unstructured data. Add EBS only when an application requires directly attached, pre-configured I/O — such as a database requiring specific IOPS. Add NAS when multiple compute nodes need concurrent read/write access to the same file system.