What Is COS?
COS is a cloud-based, non-hierarchical distributed storage product that provides you with cost-effective, fast, and reliable data storage solutions. COS stores your data across multiple availability zones (AZs) in a redundant manner and allows multiple clients or application threads to read or write to the data at the same time.
You can use web APIs to store and search for data through Cloud Virtual Machine (CVM) instances or over the Internet. You can also use the URL of a specified domain name to store and search for the content of each individual data object in COS through HTTP/HTTPS protocol.
What Is the Difference Between COS and Cloud File Storage (CFS)?
COS has no limit on directory hierarchy or data format and can store any amount of data. There is no upper limit on the storage capacity of buckets where no partitioning is required. It supports High Availability (HA) architecture deployment to ensure the eventual consistency of data but does not have features such as file lock. Its APIs can be accessed with the HTTP or HTTPS protocol, and its SDKs and tools can be integrated into your business. Objects uploaded to COS can be accessed or downloaded directly through URLs.
CFS uses common network file transfer protocols and can create file systems and implement large-scale expansion, but needs to be mounted onto CVM for use. It can store data for a wide range of applications such as websites, online distribution, and archiving. Featuring high computing throughput and extremely high availability and persistence, it is also suitable for scenarios demanding high concurrency or shared storage.
What Is the Difference Between COS and Cloud Block Storage (CBS)?
COS has no limits on file systems, directory structure, number of files, and storage capacity, and its storage needs to be managed and accessed via web APIs. It offers various SDKs and tools for integration, which can also be used separately without CVM. COS supports access to massive amounts of data but is not suitable for scenarios involving millisecond-level response or random read/write.
CBS needs to be used together with CVM and can only be mounted for use after the file system is partitioned or formatted. Based on its different types, it offers products with different performance metrics such as IOPS and throughput for different stand-alone usage scenarios.
Why Does the Access Link of a Public Read File Expire?
First, you can get the object address and the signed URL on the object detail page in the COS console.
If your file is public read:
- If you want your file to be always accessible to others, it is recommended that you directly use the object address.
- If you only want your file to be accessible to others for a specific period, it is recommended that you directly replicate the signed URL, which carries the signature parameters and is valid for 1 hour.
If your file is private: - If you want your file to be always accessible to others, it is recommended that you change the file access permission to public read/private write and use the object address.
- If you want your file to be accessible to others for a specific period, it is recommended that you directly replicate the signed URL, which carries the signature parameters and is valid for 1 hour.
What Is a "Folder" or "Directory" in COS?
The concepts of folder and directory do not apply to COS. However, to accommodate the usage habits of different users, COS simulates the display of "folders" in the console with reference to the directory structure of traditional file management. For more information, see the document Folders and Directories.
Can COS Files Be Recovered After Being Deleted?
The data redundancy storage mechanism of COS is designed for scenarios where you need to recover data in case of faults in hardware such as servers. If you proactively and manually delete your data from COS or configure automated deletion, the data will be deleted as requested and cannot be recovered.
You can proactively delete files in the following ways:
- Use the COS console to delete a single file, delete files in batches, and clear incomplete multipart uploads or empty buckets.
- Use the COSCMD tool to delete files.
- Use COS APIs or SDKs to delete files.
- Use the COS lifecycle management feature to delete files regularly.
- Use the full sync feature of COS cross-region replication to synchronize the addition, modification, and deletion operations between buckets in different regions, so that existing files with the same name will be overwritten or deleted in the synchronized destination bucket.
How Can I Avoid Accidental Deletion?
- Back up the files in your bucket regularly in the following ways:
- Use the cross-region replication feature to implement intra-region or cross-region bucket data backup.
- Use COS APIs or SDKs regularly to back up your data to other COS buckets.
- Use versioning to save the historical versions of your data.
- Use COS permission management. See Access Management Practices:
- Separate read permission and write permission. For businesses where you only need to read data, only use a sub-account with read permission or a temporary key to access the data.
- Separate permissions for different buckets. For different businesses, only authorize permissions for buckets, directories, and operations within the scope of that particular business.
- Do not use a root account to access COS.
- Use a temporary key to access COS.
- Properly manage your data access secrets, such as the account password, CAM sub-account access secrets, and API key.
Does COS Support the Data Statistics Feature?
With the COS capability of monitoring stored data, you can learn the status and trends of all the data in the monitoring data window. To view general data trends, you can go to the overview page in the COS console to view data such as the storage size, number of requests, and traffic based on the dimensions of different storage types.
To view statistics of a single bucket, see Basic Data Statistics.
In addition, you can also view the monitoring information of different buckets on the Cloud Monitor page and configure different alarm policies according to your business needs.
Does COS Support Image Compression?
COS is a distributed storage service for unstructured data and does not support image compression.
Does COS Support Thumbnail Generation?
COS is a distributed storage service for unstructured data and does not support thumbnail generation.
Does COS Support Video Transcoding?
COS is a distributed storage service for unstructured data and does not support video transcoding.
Does COS Support Auto Decompression of Uploaded Files?
COS is a distributed storage service for unstructured data and does not support file decompression.