Data loss possibility calling 'CopyAsync' or 'CopyDirectoryAsync' with CopyMethod.ServiceSideSyncCopy (To fix in 2.0.1)

[vinjiang]

We just identified a code defect that may result unexpected data on destination under the following conditions:

• Invoke DMLib with TransferManager.CopyAsync(source, dest, CopyMethod.ServiceSideSyncCopy) and TransferManager.CopyDirectoryAsync(sourceDir, destDir, CopyMethod.ServiceSideSyncCopy)
• source and dest are both Page Blob or File
• Blob/File in transfer has size smaller than 148MB won't hit this issue. The larger size file will have higher possibility on hitting this issue
• DMLib version is 1.3 or 2.0

This regression was introduced by this commit and the fix is in this PR. We are going to release a hotfix once the release validation is done. Before the hotfix is ready, we strongly recommend to stop using the specific version(s) of DMLib under the above situation; alternatively, you may use SyncCopy or ServicesideAsyncCopy to workaround this issue. For more details about the difference among the copy methods, please refer to CopyMethod.

To identify potential Page Blob objects impacted by this issue, you may check the logging (Blob only) on the copy destination account with the following criteria:

• The Operation can be: PutPageFromUrl(For page blob)
• The Usage Agent can contain "DataMovement/2.0.0.0", "DataMovement/2.0.0.3", "DataMovement/1.3.0.0"

Here is a sample:
1.0;2020-11-19T10:21:22.0000345Z;PutPageFromUrl;Success;201;562;562;authenticated;emmauswest;emmauswest;blob;"https://emmauswest.blob.core.windows.net/vhddest/VHD8?comp=page&update&timeout=300";"/emmauswest/vhddest/VHD8";80cb6796-c01e-006f-615d-be8bbf000000;0;167.220.255.40;2019-07-07;834;0;318;0;0;;"5e6eLz/Oe1ax1CnJQAlNGg==";;Thursday, 19-Nov-20 10:21:22 GMT;;"DataMovement/2.0.0.0 Azure-Storage/11.2.2 (.NET CLR 4.0.30319.42000; Win32NT 6.2.9200.0)";;"c82268e2-9a01-4484-901f-d7d9fd796f5d"

We sincerely apologize for the impact this issue is causing.