Background

Migration of objects with multiple versions

By default, OMS migrates only the latest version of objects in source buckets.

Storage class of destination buckets

The storage class of destination buckets can be Standard, Infrequent Access, Archive, or Deep Archive.

Migration network

Migrations over the Internet or intranets are supported. Migrations over private lines are not supported.

Metadata migration

Migration scope

A single migration task or migration task group can only migrate data of one bucket. If data of multiple buckets needs to be migrated, you need to create multiple tasks or task groups.

Symbolic links

Symbolic link files cannot be migrated. Symbolic link files will be recorded as failed, and the migration task will also be marked as failed. Other files can be migrated normally. If the source contains symbolic links, enter the actual file paths.

Migration of object ACLs

OMS cannot migrate object ACLs.

Migration speed

Generally, OMS can migrate 10 TB to 20 TB of data per day. However, the speed depends on the number and size of source objects, bandwidth, and the transmission distance over the Internet between the source and destination buckets. You are advised to create a migration task to test the migration speed. The maximum migration speed is five times the average speed of a single task because up to five tasks can be executed concurrently in a region by default.

To migrate data faster and handle more concurrent tasks, you are advised to use dedicated clusters in MgC. MgC enables you to migrate data using dedicated, scalable migration clusters and up to 20 Gbit/s of bandwidth.

Archived data

You need to restore archived data before the migration. Note that when there is archived data to be migrated, you need to:

• Create migration tasks after the restoration is complete.
• Configure a validity period for restored data based on the total amount of data to be migrated. This helps prevent migration failures because restored data becomes archived again during the migration.
• Pay your source cloud vendor for restoring archived data. To learn about the pricing details, contact your source cloud vendor.

Migration tasks

A maximum of five concurrent migration tasks is allowed for your account in each region.

A maximum of 1,000,000 migration tasks can be created in your account per region within a 24-hour period.

Migration task groups

A maximum of five concurrent migration task groups is allowed for your account in each region.

Synchronization tasks

Synchronization tasks share quotas with migration tasks and migration task groups, but enjoy a higher priority.

A maximum of five concurrent synchronization tasks is allowed for your account in each region.

Object list files

• An object list file cannot exceed 1,024 MB.
• An object list file must be a .txt file, and its metadata Content-Type must be text/plain.
• An object list file must be in UTF-8 without BOM.
• Each line in an object list file can contain only one object name, and the object name must be URL-encoded.
• Do not add invalid spaces to each line in the object list file. These spaces may cause migration failures because they may be mistakenly identified as object names.
• Each line in an object list file cannot be longer than 65,535 characters, or the migration will fail.
• The Content-Encoding metadata of an object list file must be left empty, or the migration will fail.

URL list files

• A URL list file cannot exceed 1,024 MB.
• A URL list file must be a .txt file, and its metadata Content-Type must be text/plain.
• A URL list file must be in UTF-8 without BOM.
• Each line in a URL list file can contain only one URL and one destination object name.
• Each line in a URL list file cannot be longer than 65,535 characters, or the migration will fail.
• The Content-Encoding metadata of a URL list file must be left empty, or the migration will fail.
• Do not add invalid spaces to each line in the URL list file. These spaces may cause migration failures because they may be mistakenly identified as object names.
• In a URL list file, you must use a tab character (\t) to separate the URL and destination object name in each line. The format is [URL][Tab character][Destination object name]. Chinese and special characters in the source and destination object names must be URL-encoded. For example:

   
  http://xxx.xxx.xxx.xxx.com/doc/thefile2.txt doc/thefile2.txt 
  http://xxx.xxx.xxx.xxx.com/the%20file.txt the%20file.txt 
  http://xxx.xxx.xxx.xxx.com/the%20file2.txt the+file2.txt 
  http://xxx.xxx.xxx.xxx.com/doc/thefile.txt doc/thefile.txt

  CAUTION:

  The URL encoding must start from the second character after the domain name in a line. Do not encode the protocol header, domain name, or slash before or after the domain name. Otherwise, the format verification will fail.

  In each line, use a tab character (Tab key on the keyboard) to separate the URL and the destination object name. Do not use spaces.

  In the preceding examples, after the files represented by the URLs are copied to the destination bucket, the objects are named doc/thefile2.txt, the file.txt, the file2.txt, and doc/thefile.txt.

• URLs in a list file can be accessed using HEAD and GET methods.

Failed object list files

A maximum of 100,000 failed objects can be recorded in a list file.

Traffic limiting

The traffic limiting policies for creating a migration task or task group are as follows:

A maximum of three requests per second and 60 requests per minute is allowed.