ADS-DMA Steps

Author: Sandeep Nair

articles/cosmos-db/mongodb/programmatic-database-migration-assistant-legacy.md

@@ -0,0 +1,60 @@
+---
+title: Pre-data migration steps
+titleSuffix: Azure Cosmos DB for MongoDB
+description: This doc provides an overview of the Database Migration Assistant legacy utility.
+author: sandeep-nair
+ms.author: sandnair
+ms.service: cosmos-db
+ms.subservice: mongodb
+ms.custom: 
+ms.topic: conceptual
+ms.date: 04/20/2023
+---
+
+# Database Migration Assistant utility (legacy)
+
+[!INCLUDE[MongoDB](../includes/appliesto-mongodb.md)]
+
+> [!IMPORTANT]  
+> Database Migration Assistant is a preliminary legacy utility meant to assist you with the pre-migration steps. Microsoft recommends you to use the [Azure Cosmos DB Migration for MongoDB extension](/sql/azure-data-studio/extensions/database-migration-for-mongo-extension) for all pre-migration steps.
+
+### Programmatic discovery using the Database Migration Assistant
+
+You may use the [Database Migration Assistant](https://github.com/AzureCosmosDB/Cosmos-DB-Migration-Assistant-for-API-for-MongoDB) (DMA) to assist you with the discovery stage and create the data estate migration sheet programmatically.
+
+It's easy to [setup and run DMA](https://github.com/AzureCosmosDB/Cosmos-DB-Migration-Assistant-for-API-for-MongoDB#how-to-run-the-dma) through an Azure Data Studio client. It can be run from any machine connected to your source MongoDB environment.
+
+You can use either one of the following DMA output files as the data estate migration spreadsheet:
+
+* `workload_database_details.csv` - Gives a database-level view of the source workload. Columns in file are: Database Name, Collection count, Document Count, Average Document Size, Data Size, Index Count and Index Size.
+* `workload_collection_details.csv` - Gives a collection-level view of the source workload. Columns in file are: Database Name, Collection Name, Doc Count, Average Document Size, Data size, Index Count, Index Size and Index definitions.
+
+Here's a sample database-level migration spreadsheet created by DMA:
+
+| DB Name | Collection Count | Doc Count | Avg Doc Size | Data Size | Index Count | Index Size |
+| --- | --- | --- | --- | --- | --- | --- |
+| `bookstoretest` | 2 | 192200 | 4144 | 796572532 | 7 | 260636672 |
+| `cosmosbookstore` | 1 | 96604 | 4145 | 400497620 | 1 | 1814528 |
+| `geo` | 2 | 25554 | 252 | 6446542 | 2 | 266240 |
+| `kagglemeta` | 2 | 87934912 | 190 | 16725184704 | 2 | 891363328 |
+| `pe_orig` | 2 | 57703820 | 668 | 38561434711 | 2 | 861605888 |
+| `portugeseelection` | 2 | 30230038 | 687 | 20782985862 | 1 | 450932736 |
+| `sample_mflix` | 5 | 75583 | 691 | 52300763 | 5 | 798720 |
+| `test` | 1 | 22 | 545 | 12003 | 0 | 0 |
+| `testcol` | 26 | 46 | 88 | 4082 | 32 | 589824 |
+| `testhav` | 3 | 2 | 528 | 1057 | 3 | 36864 |
+| **TOTAL:** | **46** | **176258781** | | **72.01 GB** | | **2.3 GB** |
+
+### Programmatic assessment using the Database Migration Assistant
+
+[Database Migration Assistant](https://github.com/AzureCosmosDB/Cosmos-DB-Migration-Assistant-for-API-for-MongoDB) (DMA) also assists you with the assessment stage of pre-migration planning.
+
+Refer to the section [Programmatic discovery using the Database Migration Assistant](#programmatic-discovery-using-the-database-migration-assistant) to know how to setup and run DMA.
+
+The DMA notebook runs a few assessment rules against the resource list it gathers from source MongoDB. The assessment result lists the required and recommended changes needed to proceed with the migration.
+
+The results are printed as an output in the DMA notebook and saved to a CSV file - `assessment_result.csv`.
+
+> [!NOTE]
+> Database Migration Assistant does not perform an end-to-end assessment. It is a preliminary utility meant to assist you with the pre-migration steps.
+