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Bucket Overview
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Last updated: 2025-10-11 17:41:47
Bucket Overview
Last updated: 2025-10-11 17:41:47
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Overview

A bucket is the carrier of objects, which can be understood as the "container" for storing objects, and this "container" has no upper limit of capacity. Objects are stored in buckets in a flat structure with no concept of folders and directories. You can choose to store objects in one or multiple buckets.
Note:
A bucket can contain any number of objects, but one root account can create only up to 200 buckets.

Bucket Naming Conventions

A bucket name consists of BucketName and APPID connected by a hyphen (-). The naming format for the bucket is <BucketName-APPID>.
BucketName: A string of characters manually entered by the user, with the following naming conventions:
Only lowercase letters (a-z), digits (0-9), and hyphens (-) are allowed.
The number of characters a bucket name is allowed to contain is limited by the length of the region abbreviation and APPID. The combined domain name can be up to 60 characters. For example, the domain name 123456789012345678901-1250000000.cos.ap-beijing.myqcloud.com contains 60 characters.
A bucket name cannot start or end with "-".
APPID: This is the account obtained upon successful application for a Tencent Cloud account, automatically assigned by the system with fixed and global uniqueness. It can be viewed in Account Info. When creating a bucket via console, no user input is required, but specifying the APPID is necessary when using tools, APIs, or SDKs.

Naming Example

For example, the bucket examplebucket-1250000000, where examplebucket is the BucketName (a string manually entered by the user) and 1250000000 is the APPID (automatically assigned by the system when users apply for a Tencent Cloud account).
The following are examples of valid bucket names:
examplebucket-1-1250000000
mybucket123-1250000000
1-newproject-1250000000

Region to Which the Bucket Belongs

Region is where the COS IDC is located. COS allows users to create buckets in different regions. You can select the region closest to the location where you deploy your business for the buckets so as to reduce latency and cost, and meet the compliance requirements.
For example, if your business is distributed in South China, creating buckets in the Guangzhou region can accelerate object uploads and downloads. For more information on regions, see Regions and Access Endpoints.
Note:
Region must be specified when a bucket is created and cannot be modified once specified. All objects in the bucket are stored in the IDC in the region. You cannot set regions for objects.

Bucket Permission Types

A bucket provides two types of permissions by default: public and user.
Note:
If the bucket permission is private read/write or a specified account is granted the permission, an object request needs to carry a signature for identity verification. For more information on signature, see Request Signature.
If the bucket permission is public read/private write or public read/write, an object request doesn't need to carry a signature, and anonymous users can directly access the object at the URL. However, your data may be leaked. Therefore, proceed with caution.

Public permissions

Public permissions include "Private Read/Write", "Public Read/Private Write", and "Public Read/Write". You can modify bucket access permissions in Permission Management of the bucket in the COS console. For more information, see Basic Concepts of Access Control.
Private Read/Write Only the creator of the bucket and authorized accounts have Read/Write permission on the objects in the bucket. The default access permission of a bucket is Private Read/Write, which is recommended.
Public Read/Private Write Anyone (including anonymous visitors) has Read permission on the objects in the bucket, but only the bucket creator and authorized accounts have Write permission on them.
Public Read/Write Anyone (including anonymous visitors) has Read/Write permission on the objects in the bucket, which is not recommended.

User permissions

A root account has all the permissions (full access) for buckets by default. In addition, you can add sub-accounts that are granted permissions to read/write data and permissions, and even full access.

Usage

Viewing Bucket Overview Via Console

Note:
If the sub-account does not have permission to access the dashboard, contact the root account and ask for request permission by adding user policy GetBucket.
1. Log in to the COS console and click Bucket List on the left sidebar.
2. Locate the bucket you want, and click the bucket name.
3. Click the Overview tab to enter the bucket overview page.

Usage Overview

Usage Overview shows the number of objects, incomplete multipart uploads, storage usage, traffic, and requests in the current bucket.
Note:
"Usage Overview" data is delayed for about two hours compared with real-time data. It is for monitoring purposes only. For accurate billing data, go to Billing Center to download usage details.
Number of objects/Number of incomplete multipart uploads: allows you to view the number of objects or incomplete multipart uploads in each COS storage class.
Storage amount: View storage usage for various storage types. Currently supported storage types include STANDARD, MAZ_STANDARD, STANDARD_IA, MAZ_STANDARD_IA, ARCHIVE, MAZ_ARCHIVE, DEEP_ARCHIVE, INTELLIGENT_TIERING, and MAZ_INTELLIGENT TIERING.
Note:
MAZ_STANDARD, MAZ_STANDARD_IA, MAZ_ARCHIVE, DEEP_ARCHIVE, INTELLIGENT_TIERING, and MAZ_INTELLIGENT TIERING are only supported in specific regions. For supported regions, see Storage Type Introduction.
Traffic: View month-to-date total traffic, public network downstream traffic, private network downstream traffic, CDN origin-pull traffic, and global acceleration downstream traffic for various storage types. Currently supported storage types include STANDARD, MAZ_STANDARD, STANDARD_IA, MAZ_STANDARD_IA, INTELLIGENT TIERING, and MAZ_INTELLIGENT TIERING.
Requests: Allow you to view the number of all requests, read requests and write requests for the current month.
Retrievals: Allow you to view the amount of data retrieved from STANDARD_IA and ARCHIVE.

Basic Information

Basic Information includes bucket name, region, creation time and access permissions.
Bucket Name: consists of a custom bucket name and APPID. For naming information, see Naming Conventions.
Region: specifies the region where the bucket resides.
Creation Time: specifies the time when the bucket was created.
Access Permissions: Specify the access permissions for the bucket. For more information on permissions, see Setting Access Permission.

Domain Information

Domain Information shows all the domain names/endpoints configured for the bucket.
Endpoint: the default COS access endpoint for this bucket. It is auto-generated based on the bucket’s name and region when you create a bucket.
Note:
The default domain name may pose security risks and possibly expose sensitive information. It is recommended to configure a custom domain name for your bucket. For details, see Bucket Custom Domain Name Switchover.
Default CDN acceleration domain: The domain name via CDN acceleration nodes is generated by default and can be configured manually by the user. If this feature was previously enabled, this option will be displayed. For more information, see Default CDN Acceleration Domain Name.
Custom CDN acceleration domain: Allows you to bind a custom domain name to Tencent Cloud CDN to speed up access to the objects in this bucket.
Custom endpoint: Allows you to bind your own domain name as a custom endpoint to the bucket for access to the objects in it.
Global acceleration endpoint: The auto-generated endpoint after you enable global acceleration. You can use this endpoint to speed up uploads to the bucket globally. For more information on global acceleration, please see Global Acceleration > Overview.
Static website endpoint: Allows you to access a bucket configured as a static website. For more information on static website, please see Setting Up a Static Website.

Bucket Configuration

Bucket Configuration shows the status of each bucket configuration.
MAZ Configuration: The multi-AZ storage architecture offered by COS, which can provide IDC-level disaster recovery capabilities for your data. For more information, see MAZ Feature Overview.
Metadata Acceleration: A high-performance file system feature provided by COS. For more information, see Metadata Acceleration Overview.
CORS: Represents cross-origin access which requests resources from another origin over HTTP. Two origins that differ in any one of protocol, domain name, and port are treated as different origins. For more information, see Setting Cross-Origin Access.
Versioning: Retains multiple versions of an object after you enable versioning on your bucket. It helps to retrieve your data lost due to accidental deletion or application failure. For more information, see Setting Versioning.
Origin-Pull: Leads you from COS to another origin for data access using an origin-pull rule when the object you request does not exist in the COS bucket or a specific request needs to be redirected. For more information, please see Setting Origin-Pull.
Bucket encryption: By setting bucket encryption, you can encrypt all new objects uploaded to a bucket with the specified encryption method by default. For more information, see Bucket Encryption Overview.
Inventory: The inventory feature can generate inventory reports about object attributes, configuration details, and more for your bucket on a daily, weekly, or monthly basis. For details, see Setting Inventory.
Hotlink Protection: Prevents malicious programs' cheating for public network traffic using resource URLs or stealing of resources by malicious means. For details, please see Setting Hotlink Protection.
Lifecycle: Automatically transitions or deletes specified objects within the specified time according to your lifecycle rule. For more information, see Setting Lifecycle.
Cross-Bucket Replication: Automatically replicates incremental objects asynchronously from the source bucket to the destination bucket in another region after you enable cross-region replication. For more information, see Setting Cross-Bucket Replication.
Logging: By using the logging feature, COS can record various request logs related to bucket operations to help you better manage and use your bucket. For details, see Log Storage Settings.
Tag: a bucket tag used as an identifier to help group and manage buckets. For more information, see Setting Bucket Tags.

Alarm Configuration

Alarm Configuration enables you to configure alarms on your bucket for daily monitoring purposes.
Current alarms: Show the number of ongoing alarms.
Alarm policies: Show the number of existing alarm policies.

Other Configurations

In addition to COS configuration, COS also integrates Cloud Infinite (CI) features, such as content review and data processing. For more information, see Content Review and Data Processing Overview.

Notes

COS stores objects using a flat structure instead of folders. For more information, see “Folders and Directories” in Object Overview.
Each root account (i.e., the same APPID) can create up to 200 buckets in total in all regions. There is no limit on the number of objects in a bucket.
In Tencent Cloud, the bucket name under one APPID is globally unique and must be unique.
Once a bucket is created, it cannot be renamed. To rename a bucket, you need to delete it and create another one with the desired name.
When creating a bucket, make sure to select the desired region, as the region cannot be changed once specified.
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