Configure range origin fetch

Usage notes

Procedure

1. Log on to the CDN console.

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

3. On the Domain Names page, find the target domain name and click Manage in the Actions column.

4. In the domain's navigation pane, click Video.

5. In the Range Origin Fetch section, click Modify.

6. Based on the parameter descriptions in the following table, select 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), 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	By default, Do Not Enable Range Origin Fetch is selected, which means that regardless of whether a client sends a Range request to a CDN POP, the CDN POP requests the entire file during an origin fetch, resulting in low file distribution efficiency for large files.	For example, if a request from a client to a CDN POP contains Range: bytes=0-100, the CDN POP sends a request to the origin server without the Range parameter. The origin server sends the entire file to the CDN POP. For example, if the file is 10 MB, the origin server sends the 10 MB file to the CDN POP. The CDN 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 Match Client, if a client sends a Range request to a CDN POP, the CDN POP performs an origin fetch by using a Range request. For the first origin fetch request, the CDN POP requests a data block from your origin server. The size of this block is determined by rounding up the range size from the client's request to the nearest integer multiple of the shard size. All subsequent origin fetch requests use the shard size that you specify.	For example, when the shard size is 512 KB, if a client sends a request to a CDN POP that contains Range:bytes=0-614399 (which is 600 KB), and the file is not cached on the CDN 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 CDN POP accesses the origin server by using a shard size of 512 KB.
   	Enable Range Origin Fetch (Recommended for Large File Delivery)	After Enable Range Origin Fetch (Recommended for Large File Delivery) is enabled, regardless of whether a client sends a Range request to a CDN POP, CDN POPs always use Range requests for origin fetch. All Range requests sent from CDN 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 if you select Match Client or Enable Range Origin Fetch (Recommended for Large File Delivery). The default 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 evaluates parameters in a user request to determine whether the configuration applies.	Do not use

7. Click OK to save the configuration.

Handling out-of-range HTTP Range requests

When CDN 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 CDN 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]