This topic provides answers to frequently asked questions about Object Storage Service (OSS).

General FAQ

  • What is Alibaba Cloud OSS?

    Alibaba Cloud OSS is a secure, cost-effective, highly durable, and scalable storage service that allows you to store a large volume of data. OSS is designed to provide data durability of at least 99.9999999999% (twelve 9's) and service availability of at least 99.995%.

  • What are the features of OSS?

    OSS supports RESTful API operations that do not need to be performed in the OSS console. You can store and access data from all applications anytime and anywhere. OSS is highly scalable. You are charged only for the resources that you use. You can scale OSS resources based on your requirements without compromising performance or durability.

    Aside from the API operations, OSS provides SDKs and migration tools that can help you transfer large amounts of data to and from OSS. OSS offers a selection of storage classes that are designed to meet the requirements for a variety of use cases. For example, you can store images, audio, and videos used in your apps and websites as Standard objects for frequent access, and save costs by storing infrequently accessed data that you want to retain for long periods of time as Infrequent Access (IA), Archive, or Cold Archive objects.

    For more information about the features of OSS, see Functions and features.

  • Who are the intended users of OSS?

    OSS is suitable for users who need to store large volumes of data. These users include app and software developers, game development enterprises, and webmasters of online communities, media sharing sites, and e-commerce websites.

  • What data does OSS store?

    OSS is suitable for storing attachments, high-definition images, audio and video objects, and backup objects for forums, websites, and software applications, as well as objects for various applications, file synchronization software, and online storage systems.

  • What are the advantages of OSS over local storage solutions?

    OSS allows developers to fully use the economy of scale provided by Alibaba Cloud at minimal cost without additional investments or performance degradation. Developers can focus on their own innovations without performance bottlenecks and security risks that occur due to business growth. OSS is cost-effective and easy to use.

  • What is the upper limit of the data volume that OSS can support?

    OSS does not impose limits on the total storage capacity and the storage capacity of a bucket. You can use the OSS console to upload an object up to 5 GB in size. To upload an object larger than 5 GB in size, you can use multipart upload, ossbrowser, or ossutil. For more information, see Multipart upload, Use ossbrowser, and Overview.

  • What are the storage classes provided by OSS?

    OSS provides the following storage classes to cover various data storage scenarios from hot data storage to cold data storage: Standard, Infrequent Access (IA), Archive, and Cold Archive. The Standard storage class provides high-durability, high-availability, and high-performance object storage services that support frequent data access. The IA storage class is suitable for storing data that is accessed once or twice a month. In addition, the unit price of IA storage is lower than that of Standard storage. The Archive storage class is suitable for storing archive data for at least six months. The Cold Archive storage class is suitable for storing cold data for a long period of time. For more information, see Overview.

  • Does Alibaba Cloud use the data that is stored in OSS?

    Alibaba Cloud does not use or disclose your data without your authorization. Alibaba Cloud processes user data only based on your service requirements or requirements of laws and regulations. For more information, see Service terms.

  • Does Alibaba Cloud use OSS to store their own data?

    Yes. Alibaba Cloud developers also use OSS to store authorized data for various projects. These projects rely on OSS to perform key business operations.

  • How does OSS ensure service availability when traffic spikes occur?

    OSS is designed to handle traffic spikes that occur due to traffic that is sent from Internet applications. To ensure service continuity during traffic spikes, OSS does not impose limits on storage capacity. For the billing of OSS, the pay-as-you-go billing method is used. OSS ensures that loads are balanced to prevent applications from being affected by traffic spikes.

  • How is data organized in OSS?

    OSS is a distributed object storage service that stores data as key-value pairs. When you store an object, you must specify an object name (key). The key can then be used to obtain the content of the object.

    Keys can also be used to simulate features of directories. OSS uses a flat structure for objects instead of a hierarchical structure. All elements are stored as objects in buckets. However, OSS supports directories as a concept to group objects and simplify management. When you use APIs or SDKs to configure an object, you can specify the key value, which is a full name that includes a prefix for the object to manage other objects. For example, if you set the key of an object to dir/example.jpg, a directory named dir is created in the current bucket and an object named example.jpg is created in the directory. If you delete the dir/example.jpg object, the dir directory is also deleted.

  • How do I get started with OSS?
    1. Before you use OSS, make sure that you have created an Alibaba Cloud account and completed real-name verification. For more information, see Sign up to Alibaba Cloud.

    2. After you register an Alibaba Cloud account, you must activate OSS. For more information, see Activate OSS.
    3. Optional:After OSS is activated, the default billing method is pay-as-you-go. If you want to further reduce OSS fees, we recommend that you purchase resource plans. For more information, see Purchase resource plans.
    4. You can use OSS by using the OSS console, ossbrowser, ossutill, or OSS SDKs for various programming languages. For more information, see Get started with OSS.

FAQ about Alibaba Cloud regions

  • Where is my data stored?

    When you create an OSS bucket, you can specify an Alibaba Cloud region in which the bucket is located. By default, OSS backs up your data to one zone in the specified region. If you enable zone-redundant storage (ZRS), OSS can back up your data to three different zones within the same region. When one zone becomes unavailable, other zones continue to provide access to data.

  • What is an Alibaba Cloud region?

    An Alibaba Cloud region is a geographical region that contains multiple geographically isolated zones. These zones are connected to each other over networks that feature low latency, high throughput, and high redundancy.

  • What is a zone?

    Each region has multiple isolated locations known as zones. Each zone has its own independent power supply and networks. The network latency between instances that are deployed in the same zone is lower than the network latency between instances that are deployed in different zones. Zones in the same region are connected over the internal network. When a zone becomes unavailable, other zones are not affected.

  • How do I determine which region to store my data in?

    When you select a region, we recommend that you consider factors such as physical locations, relationships between cloud services, and resource prices. For more information, see Choose an OSS region.

FAQ about billing

  • How are users charged fees?

    OSS supports the pay-as-you-go billing method to allow you to pay for the resources that you use. You are not charged a minimum usage fee when you use OSS. You can also purchase resource plans. Resource plans are used to offset fees incurred due to resource usage. In most cases, resource plans are more cost-effective. For more information about prices, visit the OSS pricing page.

  • How am I charged fees when other accounts are used to access my OSS resources?

    When other accounts access your OSS resources, you are charged fees based on standard pricing. You can enable the pay-by-requester mode for your bucket so that requesters are charged fees generated by sending requests and downloading OSS data. For more information, see Pay-by-requester.

  • How do I deactivate OSS?

    If you deactivate OSS, your business may be affected. Therefore, OSS does not support service deactivation. However, you can use other methods to delete your OSS resources to stop incurring fees for these resources. For more information, see How do I deactivate OSS or stop OSS charging my resources?

FAQ about data security and protection

  • Is data stored in OSS in a secure manner?

    OSS ensures the security of the data that is stored. By default, only the resource owner can access resources in a bucket. OSS provides user identity verification to manage access to data. You can use various access control policies at the bucket level or object level, such as access control lists (ACLs), to grant specific permissions to specific users and user groups. The OSS console displays the buckets that are available for public access. You can set the bucket ACL to private if you do not want other users to access your bucket or object. If you set the bucket ACL to public read or public read/write, a message that indicates security risks appears. For more information about the security of OSS, see Overview.

  • How do I perform access control on my OSS data?

    OSS provides multiple access control methods, including ACLs, RAM policies, and bucket policies, to allow users to access objects stored in buckets. For more information, see Overview.

  • What data encryption methods does OSS provide?

    Server-side encryption: Objects uploaded to a bucket that have server-side encryption enabled are encrypted before they are committed to storage. When you attempt to download objects from the bucket, OSS decrypts the object before returning the object. A header is added in the response to indicate that the object is encrypted on OSS servers. For more information about server-side encryption, see Server-side encryption.

    Client-side encryption: Objects are encrypted on the local client before they are uploaded to OSS. For more information about client-side encryption, see Client-side encryption.

  • How do I prevent data stored in buckets from being accidentally deleted or overwritten?

    You can configure versioning for a bucket to protect objects stored in the bucket against unintended operations. When versioning is enabled for a bucket, existing objects in the bucket are stored as previous versions when they are overwritten or deleted. Previous versions provide an insurance against accidental deletions or overwrites. You can recover objects to a previous version at any time. For more information about versioning, see Overview.

  • What is a retention policy?

    OSS supports the Write Once Read Many (WORM) strategy that prevents an object from being deleted or overwritten for a specified period of time. You can configure time-based retention policies for buckets. After a retention policy is configured and locked for a bucket, you can read objects from or upload objects to the bucket. However, objects in the bucket or the retention policy cannot be deleted within the retention period specified by the retention policy. You can delete the objects only after the retention period expires.

    You can configure retention policies for infrequently accessed important data that you do not want to be modified or deleted. Such data includes medical records, technical documents, and contracts. You can store these objects in a specified bucket and configure a retention policy for the bucket.

  • Does OSS modify the uploaded objects?

    OSS does not modify the uploaded objects. If you want to modify an object, you can download the object to your local computer.

FAQ about data replication

  • How do I replicate data from a bucket to another bucket in a different region?

    Multiple cross-region replication (CRR) rules can be configured for a bucket to store multiple copies of the data in different regions. CRR provides automatic and asynchronous (near real-time) replication of objects across buckets in different OSS regions. Operations such as creating, overwriting, and deleting objects can be synchronized from a source bucket to a destination bucket.

  • What are the advantages of CRR?
    • Compliance requirements: Although OSS stores multiple replicas of each object in physical disks, replicas must be stored at a distance from each other to comply with regulations. CRR allows you to replicate data between geographically distant OSS data centers to satisfy these compliance requirements.
    • Minimum latency: You have users who are located in two geographical locations. To minimize the latency when the users access objects, you can maintain replicas of objects in OSS data centers that are geographically closer to these users.
    • Data backup and disaster recovery: You have high requirements for data security and availability, and want to explicitly maintain replicas of all written data in a second data center. If one OSS data center is damaged in a catastrophic event such as an earthquake or a tsunami, you can use backup data from the other data center.
    • Data replication: For business reasons, you may need to migrate data from one OSS data center to another data center.
    • Operational reasons: You have compute clusters deployed in two different data centers that need to analyze the same group of objects. You can choose to maintain object replicas in these regions.
  • How am I charged fees when I use CRR?

    After CRR is enabled, cross-region traffic is generated when you replicate objects across buckets in the source and destination regions. You are charged for the traffic that is generated when you use CRR. Each time an object is synchronized, OSS calculates the number of requests and the requests are charged on a pay-as-you-go basis. The traffic that is generated when you use CRR can be charged only on a pay-as-you-go basis. Resource plans are unavailable for CRR.

FAQ about data query

How do I query data in OSS?

OSS supports the SelectObject operation that allows you to use SQL statements to query specific data in a CSV or JSON object instead of querying the entire object. The SelectObject operation simplifies the process used to query data and filter the data into smaller and more specific data sets. This operation is suitable for the multipart query of large objects, query of JSON objects, and analysis of log objects. For more information about data query, see Query objects.

FAQ about storage management

  • What is OSS lifecycle management? How do I use lifecycle management to minimize OSS storage costs?
    You can configure a lifecycle rule to regularly delete objects that are no longer accessed or convert the storage class of cold data to IA, Archive, or Cold Archive. This makes data management easier and reduces storage costs. For example, you can configure lifecycle rules in the following scenarios:
    • A medical institution stores its medical records in OSS. These objects are occasionally accessed within six months after they are uploaded, and almost never after that. In this case, you can configure a lifecycle rule to convert the storage class of these objects to Archive 180 days after they are uploaded.
    • A company stores the call records of its customer service hotline in OSS. These objects are frequently accessed within the first two months, occasionally after two months, and almost never after six months. After two years, these objects no longer need to be stored. In this case, you can configure a lifecycle rule to convert the storage class of these objects to IA 60 days after they are uploaded and to Archive 180 days after they are uploaded, and then delete them 730 days after they are uploaded.
    • More than 1,000 objects need to be deleted from a bucket. However, only up to 1,000 objects can be manually deleted at a time. In this case, you can configure a lifecycle rule that is used to delete all objects in the bucket the next day. This way, all objects in the bucket can be deleted the next day.

    For more information about lifecycle management, see Lifecycle rules based on the last modified time.

  • How do I periodically obtain the information about objects stored in a bucket?

    You can use the bucket inventory feature to export information about specific objects in a bucket on a daily or weekly basis. Exported object information includes the number, sizes, storage classes, and encryption status of the objects. For more information about the bucket inventory feature, see Bucket inventory.