Merge pull request #102562 from normesta/normesta-azcopy

Some text for a new feature

Author: PRMerger10

articles/storage/common/storage-ref-azcopy-copy.md

@@ -212,7 +212,7 @@ Copy a subset of buckets by using a wildcard symbol (*) in the bucket name. Like
 
 **--no-guess-mime-type**                   Prevents AzCopy from detecting the content-type based on the extension or content of the file.
 
-**--overwrite** string                     Overwrite the conflicting files and blobs at the destination if this flag is set to true. Possible values include 'true', 'false', and 'prompt'. (default "true")
+**--overwrite** string                     Overwrite the conflicting files and blobs at the destination if this flag is set to true. Possible values include 'true', 'false', 'ifSourceNewer', and 'prompt'. (default "true")
 
 **--page-blob-tier** string                Upload page blob to Azure Storage using this blob tier. (default "None")
 

articles/storage/common/storage-use-azcopy-configure.md

@@ -4,7 +4,7 @@ description: Configure, optimize, and troubleshoot AzCopy.
 author: normesta
 ms.service: storage
 ms.topic: conceptual
-ms.date: 10/16/2019
+ms.date: 01/28/2020
 ms.author: normesta
 ms.subservice: common
 ms.reviewer: dineshm
@@ -37,6 +37,14 @@ Currently, AzCopy doesn't support proxies that require authentication with NTLM
 
 You can benchmark performance, and then use commands and environment variables to find an optimal tradeoff between performance and resource consumption.
 
+This section helps you perform these optimization tasks:
+
+> [!div class="checklist"]
+> * Run benchmark tests
+> * Optimize throughput
+> * Optimize memory use 
+> * Optimize file synchronization
+
 ### Run benchmark tests
 
 You can run a performance benchmark test on specific blob containers to view general performance statistics and to identity performance bottlenecks. 
@@ -93,6 +101,14 @@ Express this value in gigabytes (GB).
 | **Linux** | `export AZCOPY_BUFFER_GB=<value>` |
 | **MacOS** | `export AZCOPY_BUFFER_GB=<value>` |
 
+### Optimize file synchronization
+
+The [sync](storage-ref-azcopy-sync.md) command identifies all files at the destination, and then compares file names and last modified timestamps before the starting the sync operation. If you have a large number of files, then you can improve performance by eliminating this up-front processing. 
+
+To accomplish this, use the [azcopy copy](storage-ref-azcopy-copy.md) command instead, and set the `--overwrite` flag to `ifSourceNewer`. AzCopy will compare files as they are copied without performing any up-front scans and comparisons. This provides a performance edge in cases where there are a large number of files to compare.
+
+The [azcopy copy](storage-ref-azcopy-copy.md) command doesn't delete files from the destination, so if you want to delete files at the destination when they no longer exist at the source, then use the [azcopy sync](storage-ref-azcopy-sync.md) command with the `--delete-destination` flag set to a value of `true` or `prompt`. 
+
 ## Troubleshoot issues
 
 AzCopy creates log and plan files for every job. You can use the logs to investigate and troubleshoot any potential problems.