Hi Jun,
It is possible to remap Smart search indexes to another blob. You can use a code similar to the following:
var externalContainerPath = "~/App_Data/CMSModules/SmartSearch/"; // Path to Smart search index default location
AbstractStorageProvider searchProvider = new StorageProvider("azure", "CMS.AzureStorage");
searchProvider.CustomRootPath = "myCustomBlob"; // Blob storage container
searchProvider.PublicExternalFolderObject = true;
StorageHelper.MapStoragePath(externalContainerPath, searchProvider);