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README.md
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README.md

Copy Mode

Contents

  1. Limitations
  2. Approach
    2.1. General
    2.2. Filesystem Storage Case
    2.3. HTTP Storage Case
  3. Configuration

The copy mode functionality allows to perform a copy operation on the multiple files instead of write one. The performance rates may be significantly different for the copy and write operations. Some cloud storage APIs also support copying the objects (S3 and Swift) so the functionality may be a general. In case of S3 and Swift there's no payload sent while copying the objects so these requests may be significantly faster than writing new objects.

1. Limitations

  1. Works only if the input path is different from the output one
  2. Copying the containers (Swift) is not supported
  3. Copying the buckets (S3) is not supported
  4. Copying the objects (Atmos) while using /rest/object interface is not supported yet

2. Approach

2.1. General

Copy mode is enabled if:

  • --load-op-type option is set to create (this is by default) and
  • one of the item inputs is configured:
    • --item-input-path is set to existing bucket/container/directory or
    • --item-input-file is set to existing items list file

2.2. Filesystem Storage Case

In case of copying the filesystem directories there's a size may be calculated, so there's a size and bandwidth (MB/sec) metrics are available.

2.3. HTTP Storage Case

Note: Cloud Storage object copy requests don't contain any payload so the byte count related metrics are not calculated (remain zero).

2.3.1. S3 Objects Copying

The source object path is specified with x-amz-copy-source header.

2.3.2. Swift Objects Copying

There are two variants of object copy requests:

  • Using HTTP method COPY and Destination header.
  • Using HTTP method PUT and X-Copy-From header.

The 2nd variant is preferred ss far as COPY HTTP method is not standard.

The source object URI is specified with X-Copy-From header.

3. Configuration

In order to perform a copy load step it's necessary:

  • Use create load type.
  • Specify --item-input-path (the source container/bucket/directory, contains the items to copy) or --item-input-file to a proper value.
  • Specify --item-output-path (the target container/bucket/directory) to a proper value.

For details, see the example scenario located at: <USER_HOME_DIR>/.mongoose/<VERSION>/example/scenario/js/types/additional/copy_load_using_env_vars.js.