Configure range origin fetch

Usage notes

• Before you enable range origin fetch, ensure that your origin server supports range requests. This means the origin server must be able to process the Range field in an HTTP header and respond with a 206 Partial Content status code. If your origin server does not support range requests, enabling this feature will cause resource caching to fail.

• The Multipart Ranges feature is disabled by default and is not automatically enabled when you enable range origin fetch. To enable the Multipart Ranges feature, submit a ticket.

• Enabling the range origin fetch feature increases the QPS for origin fetches. If rate limiting is enabled on your origin server, this may trigger its rate limiting rules. As a workaround, call the DescribeL2VipsByDomain operation to query the IP addresses of the DCDN origin fetch POPs, and add the IP addresses of the DCDN origin fetch POPs to the IP address whitelist of your origin server.

Procedure

1. Log on to the DCDN console.

2. In the left-side navigation pane, click Domain Names.

3. On the Domain Names page, find the domain name that you want to manage and click Configure.

4. In the left-side navigation tree of the domain name, click Origin Fetch.

5. On the Origin Fetch tab, find the Range Origin Fetch section and click Modify.

6. Based on the parameter descriptions in the following table, set Range Origin Fetch to Do Not Enable Range Origin Fetch, Match Client, or Enable Range Origin Fetch (Recommended for Large File Delivery).

   If you select Match Client or Enable Range Origin Fetch (Recommended for Large File Delivery) for Range Origin Fetch, you can set the Shard Size. The default shard size is 512 KB.

   Parameter	Option	Description	Example
   Range Origin Fetch	Do Not Enable Range Origin Fetch	The default setting is Do not use range origin fetch. With this setting, regardless of whether a client sends a Range request to a DCDN point of presence (POP), the DCDN POP fetches the entire file from the origin. This results in lower file distribution efficiency for large files.	For example, if a request from a client to a DCDN POP contains Range: bytes=0-100, the DCDN POP sends a request to the origin server without the Range parameter. The origin server sends the entire file to the DCDN POP. For example, if the file is 10 MB, the origin server sends the 10 MB file to the DCDN POP. The DCDN POP caches the file that it receives from the origin server and then responds to the client with the content for the Range: bytes=0-100 request.
   	Match Client	After you enable Follow Client Range Requests, when a client sends a Range request to a DCDN node, the DCDN node sends a Range request to the origin server. The first back-to-origin request from the DCDN node retrieves a data chunk whose size is the Range size of the client request rounded up to the nearest integer multiple of the shard size. All subsequent requests to your origin server are based on the shard size that you specify.	For example, when the shard size is 512 KB, if a client sends a request to a DCDN POP that contains Range:bytes=0-614399 (which is 600 KB), and the file is not cached on the DCDN POP, the first origin fetch retrieves a 1024 KB shard (600 KB rounded up to 1024 KB). For subsequent requests for other uncached shards of the file, the DCDN POP accesses the origin server by using a shard size of 512 KB.
   	Enable Range Origin Fetch (Recommended for Large File Delivery)	After you enable Enable Range Origin Fetch (Recommended for large files), regardless of whether a client sends a Range request to a DCDN point of presence (POP), the DCDN POP uses Range requests for origin fetch. All origin-fetch Range requests from the DCDN POPs to the origin server use the shard size that you specify.	None
   Shard Size	512 KB 1 MB 2 MB 4 MB	You can set the shard size for range origin fetch if the mode is set to Match Client or Enable Range Origin Fetch (Recommended for Large File Delivery). The default shard size is 512 KB.	1 MB
   Rule Condition	A rule condition determines whether a configuration applies to a request by evaluating various parameters in the request. Important When a feature references rule conditions configured in the rules engine, the execution order follows the priority of the associated rule conditions, not the order of the feature configurations. Do not use conditions: Disables conditional rules. You can add or edit conditional rules in Rules engine.	A rule condition identifies parameters in user requests to determine whether a configuration applies to a specific request.	Disable

Handling out-of-range HTTP Range requests

When fetches large files from an OSS origin server, issues may occur if the OSS server responds with a cache-control:no-cache policy or if a client request to triggers a Range-based origin fetch. These issues can manifest as abnormally slow downloads or even timeouts (after about 30 seconds), and a dropped connection when an out-of-range slice (such as the last slice of the file) is downloaded.

• Behavior without a compatibility policy

  If an HTTP Range request is valid, Object Storage Service (OSS) returns a 206 response and includes the Content-Range header. If an HTTP Range request is invalid, or if the specified range is out of bounds, the Range request is ignored. OSS returns a 200 response and transfers the entire object. The following examples show invalid HTTP Range requests and explain the errors.

  Note

  The following examples assume an object size of 1000 bytes, with a valid range of 0 to 999. To prevent the specified range from being out of bounds, send a HeadObject request to get the object size before you read the range.

  • Range: byte=0-499: Invalid format. byte should be bytes.

  • Range: bytes=0-1000: The end byte, 1000, is out of the valid range.

  • Range: bytes=1000-2000: The specified range is out of the valid range.

  • Range: bytes=1000-: The start byte is out of the valid range.

  • Range: bytes=-2000: The specified range is out of the valid range.

  Use the following command to test the validity of the Range parameter:

  curl -r 0-100 http://xxxx.oss-cn-hangzhou.aliyuncs.com/xx.zip -o /tmp/xx1.zip -v

• Behavior with a compatibility policy

  Add the x-oss-range-behavior:standard header to an HTTP Range request to change how OSS behaves when the specified range is out of bounds. The following examples show how the behavior changes:

  Note

  The following examples assume an object size of 1000 bytes, with a valid range of 0 to 999. If you use an HTTP Range request to get part of a large file and select an invalid range, OSS returns an InvalidRange error code. For more information about how to resolve this issue, see OSS returns a 416 error. The detailed error message is as follows:

  The requested range cannot be satisfied

  • Range: bytes=500-2000: The end byte is out of the valid range. OSS returns the content in the byte range of 500 to 999.

  • Range: bytes=1000-2000: The start byte is out of the valid range. OSS returns a 416 (InvalidRange) error.

  • Range: bytes=1000-: The start byte is out of the valid range. OSS returns a 416 (InvalidRange) error.

  • Range: bytes=-2000: The specified range is out of the valid range. OSS returns the content in the byte range of 0 to 999, which is the complete file.

  This topic provides the following HTTP Range request examples.

  Note

  The following examples assume an object size of 1000 bytes, with a valid range of 0 to 999.

  • Request the content of an object within the byte range of 0 to 499.

    GET /ObjectName
    Range: bytes=0-499
    Host: bucket.oss-cn-hangzhou.aliyuncs.com
    Date: Fri, 18 Oct 2019 02:51:30 GMT
    Authorization: Signature
    
    206 (Partial Content)
    content-length: 500
    content-range: bytes 0-499/1000
    connection: keep-alive
    etag: "CACF99600561A31D494569C979E6FB81"
    x-oss-request-id: 5DA928B227D52731327DE078
    date: Fri, 18 Oct 2019 02:51:30 GMT
    [500 bytes of object data]

  • Request the content of an object from byte 500 to the end of the file.

    GET /ObjectName
    Range: bytes=500-
    Host: bucket.oss-cn-hangzhou.aliyuncs.com
    Date: Fri, 18 Oct 2019 03:24:39 GMT
    Authorization: Signature
    
    206 (Partial Content)
    content-length: 500
    content-range: bytes 500-999/1000
    etag: "CACF99600561A31D494569C979E6FB81"
    x-oss-request-id: 5DA9307750EBE33332E3720A
    date: Fri, 18 Oct 2019 03:24:39 GMT
    [500 bytes of object data]

  • Request the last 500 bytes of an object.

    GET /ObjectName
    Range: bytes=-500
    Host: bucket.oss-cn-hangzhou.aliyuncs.com
    Date: Fri, 18 Oct 2019 03:23:22 GMT
    Authorization: Signature
    
    206 (Partial Content)
    content-length: 500
    content-range: bytes 500-999/1000
    etag: "CACF99600561A31D494569C979E6FB81"
    x-oss-request-id: 5DA9302A6646AC37397F7039
    date: Fri, 18 Oct 2019 03:23:22 GMT
    [500 bytes of object data]