# Migrate to Amazon DocumentDB using AWS Database Migration Service (DMS): Quick Start Guide
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**Topics**
+ [Prepare the DMS source](#migrate-qs-dma-source)
+ [Setup DMS](#migrate-qs-dms-setup)
+ [Enable DocumentDB compression](#migrate-qs-comp)
+ [Create a replication task](#migrate-qs-create)
+ [Monitor progress](#migrate-qs-monitor)
+ [Additional information](#migrate-qs-info)

## Prepare the DMS source
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See [Enabling change streams](change_streams.md#change_streams-enabling) to enable DocumentDB change streams or enable the MongoDB Oplog to support DMS Change Data Capture (CDC).
+ The DMS source must retain all ongoing changes until DMS full load completes for all included collections.
+ DocumentDB change streams are time based. Make sure your `change_stream_log_retention_duration` setting is large enough to cover the time to complete the full load.
+ The MongoDB Oplog is a fixed size. Make sure it is sized to hold all operations during full load.

## Setup DMS
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Create DMS instance, source, and target endpoints and test each endpoint.

## Enable DocumentDB compression
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Enable compression by attaching a custom parameter group to your DocumentDB cluster and updating default\$1collection\$1compression parameter to enabled. See [Managing collection-level document compression](doc-compression.md) for more information.

## Create a replication task
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1. In the DMS console, in the navigation pane, choose **Migrate or replicate**, then choose **Tasks**.

1. Choose **Create task**.

1. On the **Create task** page, in the **Task configuration** section:
   + Enter a unique and meaningful **Task identifier** (for example, "mongodb-docdb-replication").
   + Choose the source endpoint you created previously in the **Source database endpoint** drop-down menu.
   + Choose the target endpoint you created previously in the **Target database endpoint** drop-down menu.
   + For **Task type**, choose **Migrate and replicate**.

1. In the **Settings** section:
   + For **Task logs**, check the **Turn on CloudWatch** logs box.
   + For **Editing mode** (at the top of the section), choose **JSON editor** and set the following attributes:
     + Set `ParallelApplyThreads` to 5 (under `TargetMetadata`). This enables \$11000 insert/update/delete ops per second in CDC.
     + Set `MaxFullLoadSubTasks` to 16 (under `FullLoadSettings`). Consider increasing this depending on your instance size.
     + For large collections (over 100 GB), enable auto-partition (under Table Mapping and under the `parallel-load` attribute):
       + "type": "partitions-auto"
       + "number-of-partitions": 16

## Monitor progress
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Use the AWS DMS console or create a custom dashboard ([dashboarder tool](https://github.com/awslabs/amazon-documentdb-tools/tree/master/monitoring/docdb-dashboarder)) to track migration. Focus on the following metrics:
+ **FullLoadThroughputBandwidthTarget** — Measures the network bandwidth (in KB/second) used by DMS when transferring data to the target database during the full load phase of migration.
+ **CDCLatencyTarget** — Measures the time delay (in seconds) bewteen when a change occurs in the source database and when that change is applied to the target database.
+ **CDCThroughputRowsTarget** — Measures the number of rows per second that DMS is applying to the target database during the ongoing replication phase of migration.

## Additional information
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For more information about Amazon DocumentDB and AWS DMS, see: See for more information.
+ [Amazon DocumentDB migration runbook](docdb-migration-runbook.md)
+ [Migrating from MongoDB to Amazon DocumentDB](https://docs.aws.amazon.com/dms/latest/sbs/chap-mongodb2documentdb.html)