Help Center/ Object Storage Service/ obsutil/ Object Commands/ Synchronously Downloading Incremental Objects
Updated on 2024-05-17 GMT+08:00
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Synchronously Downloading Incremental Objects

Function

This function synchronizes all content in the specified path of the source bucket to the target bucket on OBS, ensuring that the content is consistent between the specified path of the source bucket and the target bucket. Incremental synchronization has the following meanings: (1) Increment: Compare the source object with the target file and download only the source object that has changes. (2) Synchronization: After the command is executed, ensure that the specified path of the source bucket is a subset of the local target path. That is, any object in the specified path of the source bucket has its corresponding file in the local target path.

  • Do not change the source objects in the OBS bucket when synchronously downloading objects. Otherwise, the synchronization may fail or data may be inconsistent.
  • Each object can be synchronously downloaded only when it does not exist in the local path, its size is different from the namesake one in the local path, or it has the latest modification time.

When you compare each local file with data in the bucket, a billable HEAD request is generated. For details, see Requests.

Command Line Structure

  • In Windows 
    obsutil sync obs://bucket[/key] folder_url [-tempFileDir=xxx] [-dryRun] [-vlength] [-vmd5] [-j=1] [-p=1] [-threshold=52428800] [-ps=auto] [-include=*.xxx] [-exclude=*.xxx] [-timeRange=time1-time2] [-mf] [-o=xxx] [-cpd=xxx] [-config=xxx] [-e=xxx] [-i=xxx] [-k=xxx] [-t=xxx]
  • In Linux or macOS 
    ./obsutil sync obs://bucket[/key] folder_url [-tempFileDir=xxx] [-dryRun] [-vlength] [-vmd5] [-j=1] [-p=1] [-threshold=52428800] [-ps=auto] [-include=*.xxx] [-exclude=*.xxx] [-timeRange=time1-time2] [-mf] [-o=xxx] [-cpd=xxx] [-config=xxx] [-e=xxx] [-i=xxx] [-k=xxx] [-t=xxx]

Examples

  • Take the Windows OS as an example. Run the obsutil sync obs://bucket-test/temp d:\ temp command to download objects synchronously. 
    obsutil sync obs://bucket-test/temp d:\temp

Parallel:      3                   Jobs:          3
Threshold:     524288000           PartSize:      5242880
Exclude:                           Include:
VerifyLength:  false               VerifyMd5:     false
CheckpointDir: xxxx

Task id: 3066a4b0-4d21-4929-bb84-4829c32cbd0f
OutputDir: xxxx

[======================================================] 100.00% tps:17.86 155.59 KB/s 7.20MB/7.20MB 0s
Succeed count is:   6         Failed count is:    0
Metrics [max cost:153 ms, min cost:129 ms, average cost:92.00 ms, average tps:17.86]

Task id: 3066a4b0-4d21-4929-bb84-4829c32cbd0f

Parameter Description

Parameter

Optional or Mandatory

Description

folder_url

Mandatory

Local folder path

bucket

Mandatory

Bucket name

key

Optional

Indicates the name prefix of objects to be synchronously downloaded.

The rules are as follows:

  • If this parameter is left blank, all files in the folder specified by folder_url are the same as all objects in the bucket.
  • If this parameter is configured, all files in the folder specified by folder_url are the same as the objects whose name prefix is the configured value in the bucket.
NOTE:
  • If the value of this parameter does not end with a slash (/), the obsutil tool automatically adds a slash (/) at the end of the configured value as the object name prefix.
  • For details about how to use this parameter, see Synchronous Download.

tempFileDir

Optional (additional parameter)

Indicates the directory for storing temporary files during synchronous download. The default value is the value of defaultTempFileDir in the configuration file.

NOTE:
  • Temporary files generated during multipart download are stored in this directory. Therefore, ensure that the user who executes obsutil has the write permission on the path.
  • The available space of the partition where the path is located must be greater than the size of the objects to be downloaded.

dryRun

Optional (additional parameter)

Conducts a dry run.

vlength

Optional (additional parameter)

Checks whether the sizes of the local files are the same as those of the objects in the bucket after the download is complete.

vmd5

Optional (additional parameter)

Checks whether MD5 values of the local files are the same as those of the objects in the bucket after the download is complete.

NOTE:

Objects in the bucket must contain metadata x-obs-meta-md5chksum, or MD5 verification will be skipped.

p

Optional (additional parameter)

Indicates the maximum number of concurrent multipart download tasks when downloading an object. The default value is the value of defaultParallels in the configuration file.

threshold

Optional (additional parameter)

Indicates the threshold for enabling multipart download, in bytes. The default value is the value of defaultBigfileThreshold in the configuration file.

NOTE:
  • If the size of the object to be downloaded is smaller than the threshold, download the object directly. If not, a multipart download is required.
  • If you download an object directly, no part record is generated, and resumable transmission is not supported.
  • This parameter value can contain a unit, for example, 1MB (indicating 1048576 bytes).

ps

Optional (additional parameter)

Indicates the size of each part in a multipart download task, in bytes. The default value is the value of defaultPartSize in the configuration file.

NOTE:
  • This parameter value can contain a unit, for example, 1MB (indicating 1048576 bytes).
  • The parameter can be set to auto. In this case, obsutil automatically sets the part size for each multipart task based on the source object size.

cpd

Optional (additional parameter)

Indicates the folder where the part records reside. The default value is .obsutil_checkpoint, the subfolder in the home directory of the user who executes obsutil commands.

NOTE:

A part record is generated during a multipart download and saved to the down subfolder. After the download succeeds, its part record is deleted automatically. If the download fails or is suspended, the system attempts to resume the task according to its part record when you perform the download the next time.

j

Optional for downloading objects in batches (additional parameter)

Indicates the maximum number of concurrent tasks for downloading objects synchronously. The default value is the value of defaultJobs in the configuration file.

NOTE:

The value is ensured to be greater than or equal to 1.

exclude

Optional for downloading objects in batches (additional parameter)

Indicates the matching patterns of source objects that are excluded, for example: *.txt.

NOTE:
  • The asterisk (*) represents any group of characters, and the question mark (?) represents any single character. For instance, abc*.txt indicates any file whose name starts with abc and ends with .txt.
  • You can use \* to represent * and \? to represent ?.
  • If the name of the object to be downloaded matches the value of this parameter, the object is skipped.
NOTICE:
  • You are advised to use quotation marks for the matching pattern to prevent special characters from being escaped by the OS and leading to unexpected results. Use single quotation marks for Linux or macOS and quotation marks for Windows.
  • The matching pattern applies to the absolute path of an object, including the object name prefix and object name starting from the root directory. For example, if the path of an object in the bucket is obs://bucket/src1/src2/test.txt, then the absolute path of the object is src1/src2/test.txt.
  • This matching pattern applies only to objects whose names do not end with a slash (/).
  • Multiple exclude parameters can be specified, for example, -exclude=*.xxx -exclude=*.xxx.

include

Optional for downloading objects in batches (additional parameter)

Indicates the matching patterns of source objects that are included, for example: *.jpg.

NOTE:
  • The asterisk (*) represents any group of characters, and the question mark (?) represents any single character.
  • You can use \* to represent * and \? to represent ?.
  • Only after identifying that the name of the file to be downloaded does not match the value of exclude, the system checks whether the file name matches the value of this parameter. If yes, the file is downloaded. If not, the file is skipped.
NOTICE:
  • You are advised to use quotation marks for the matching pattern to prevent special characters from being escaped by the OS and leading to unexpected results. Use single quotation marks for Linux or macOS and quotation marks for Windows.
  • The matching pattern applies to the absolute path of an object, including the object name prefix and object name starting from the root directory. For example, if the path of an object in the bucket is obs://bucket/src1/src2/test.txt, then the absolute path of the object is src1/src2/test.txt.
  • This matching pattern applies only to objects whose names do not end with a slash (/).
  • Multiple include parameters can be specified, for example, -include=*.xxx -include=*.xxx.

timeRange

Optional (additional parameter)

Indicates the time range matching pattern when synchronously downloading objects. Only objects whose latest modification time is within the configured time range are downloaded.

This pattern has a lower priority than the object matching patterns (exclude/include). That is, the time range matching pattern is executed after the configured object matching patterns.

NOTE:
  • The matching time range is represented in time1-time2, where time1 must be earlier than or the same as time2. The time format is yyyyMMddHHmmss.
  • Automatic formatting is supported. For example, yyyyMMdd is equivalent to yyyyMMdd000000, and yyyyMM is equivalent to yyyyMM01000000.
  • If this parameter is set to *-time2, all files whose latest modification time is earlier than time2 are matched. If it is set to time1-*, all files whose latest modification time is later than time1 are matched.
NOTICE:
  • Time in the matching pattern is the UTC time.
  • This matching pattern applies only to objects whose names do not end with a slash (/).

mf

Optional (additional parameter)

Indicates that the name matching pattern (include or exclude) and the time matching pattern (timeRange) also take effect on objects whose names end with a slash (/).

o

Optional (additional parameter)

Indicates the folder where operation result lists reside. After the command is executed, result lists (possibly including success, failure, and warning files) are generated in the folder. The default value is .obsutil_output, the subfolder in the home directory of the user who executes obsutil commands.

NOTE:
  • The naming rule for result lists is as follows: sync_{succeed | failed | warning}_report_time_TaskId.txt
  • By default, the maximum size of a single result list is 30 MB and the maximum number of result lists that can be retained is 1024. You can set the maximum size and number by configuring recordMaxLogSize and recordBackups in the configuration file.
  • If there are multiple folders and files and you need to confirm the detailed error information about a failed task, refer to the failure list sync_failed_report_time_TaskId.txt in the result list folder and the log files in the log path.

config

Optional (additional parameter)

User-defined configuration file for executing a command. For details about parameters that can be configured, see Parameter Description.

e

Optional (additional parameter)

Specifies the endpoint.

i

Optional (additional parameter)

Specifies the user's AK.

k

Optional (additional parameter)

Specifies the user's SK.

t

Optional (additional parameter)

Specifies the user's security token.

Response

Refer to Response for uploading an object.

Parent topic: Object Commands