Overview

Scenarios

As Internet develops, data storage scenarios become increasingly diverse. Limited storage classes cannot meet diverse storage and cost management requirements. OBS provides the following storage classes: Standard, Warm, and Cold.

Standard

Scenarios: The Standard storage class features low latency and high throughput. It is therefore good for storing frequently (multiple times a month) accessed files or small files (less than 1 MB). Its application scenarios include big data analytics, mobile apps, hot videos, and social apps.
Redundancy: The Standard storage class provides two redundancy options. Multi-AZ storage means data is stored in multiple AZs, which enables more reliability. Single-AZ storage means data is stored in a single AZ, which is more cost-effective.
Specifications: The minimum measurement object size is 64 KB. There are no requirements for the minimum storage duration.
Objects smaller than 64 KB are regarded as 64 KB in size.
Data restoration: N/A

To access objects in the Cold storage class, including reading or downloading them, accessing them with a URL, or configuring an ACL for them, you must first restore them. For more information, see Restoring an Object from Cold Storage.

Warm

Scenarios: The Warm storage class is for storing data that is infrequently (less than 12 times a year) accessed, but when needed, the access has to be fast. It can be used for file synchronization, file sharing, enterprise backups, and many other scenarios.
Redundancy: The Warm storage class provides two redundancy options. Multi-AZ storage means data is stored in multiple AZs, which enables more reliability. Single-AZ storage means data is stored in a single AZ, which is more cost-effective.
Specifications: The minimum measurement object size is 64 KB. The minimum storage duration is 30 days.
Objects smaller than 64 KB are regarded as 64 KB in size. For objects stored for less than 30 days, their storage duration is still 30 days.
Data restoration: The system automatically restores data.

To access objects in the Cold storage class, including reading or downloading them, accessing them with a URL, or configuring an ACL for them, you must first restore them. For more information, see Restoring an Object from Cold Storage.

Cold

Scenarios: The Cold storage class is ideal for storing data that is rarely (once a year) accessed. Its application scenarios include data archiving and long-term backups. This storage class is secure, durable, and inexpensive, so it can be used to replace tape libraries. To keep cost low, it may take hours to restore data from this storage class.

Redundancy: The Cold storage class only supports single-AZ redundancy. Data is stored in a single AZ, which is more cost-effective.
Specifications: The minimum measurement object size is 64 KB. The minimum storage duration is 90 days.
Objects smaller than 64 KB are regarded as 64 KB in size. For objects stored for less than 90 days, their storage duration is still 90 days.
Data restoration: Cold objects can be accessed only after being restored. The Cold storage class supports standard and expedited restoration. The standard restoration takes 3 to 5 hours, and the expedited restoration takes 1 to 5 minutes.

To access objects in the Cold storage class, including reading or downloading them, accessing them with a URL, or configuring an ACL for them, you must first restore them. For more information, see Restoring an Object from Cold Storage.

Comparison of Storage Classes

Item	Standard	Warm	Cold
Feature	Top-notch performance, high reliability and availability	Reliable, inexpensive storage with real-time access	Long-term storage for archived data at a low cost
Use cases	Cloud applications, data sharing, content sharing, and hot data storage	Web disk applications, enterprise backups, active archiving, and data monitoring	Storage of archives, medical imaging data, and videos, as well as replacement of tape libraries
Designed durability (single-AZ)	99.999999999% (11 nines)	99.999999999% (11 nines)	99.999999999% (11 nines)
Designed availability (single-AZ)	99.99%	99%	99%
Data access speed	Real-time access	Real-time access	Objects must be restored before you can access them. Standard restoration: 3 to 5 hours; Expedited restoration: 1 to 5 minutes.