Копирование файла с проверкой

Program Do(string[] args)
{
    if (args == null || args.Length != 2)
        throw new ArgumentException("Necessary to specify source and destination files");
 
    string sourceFile = args[0];
    string destinationFile = args[1];
    const int bufferSize = 8 * 1024 * 1024;
    const int partSize = 250 * 1024 * 1024;
    byte[] part = new byte[partSize];
    byte[] verifyPart = new byte[partSize];
 
    using (FileStream sourceFS = new FileStream(sourceFile, FileMode.Open, FileAccess.Read, FileShare.Read, bufferSize))
    using (FileStream destinationFS = new FileStream(destinationFile, FileMode.CreateNew, FileAccess.Write, FileShare.Read, bufferSize))
    using (FileStream verifyFS = new FileStream(destinationFile, FileMode.Open, FileAccess.Read, FileShare.ReadWrite, bufferSize))
    {
        int partCounter = 1;
        long lastBytes = sourceFS.Length;
        while (lastBytes != 0)
        {
            int currentPartSize = lastBytes < partSize ? (int)lastBytes : partSize;
            long currentPosition = sourceFS.Position;
            Console.WriteLine($"Part {partCounter} of {sourceFS.Length / partSize + (sourceFS.Length % partSize != 0 ? 1 : 0)}:");
 
            ConsoleWriteFromStart("Reading from source");
            sourceFS.Read(part, 0, currentPartSize);
 
            ConsoleWriteFromStart("Writing to destination");
            destinationFS.Write(part, 0, currentPartSize);
            destinationFS.Flush();
            //destinationFS.Seek(-currentPartSize, SeekOrigin.Current);
 
            ConsoleWriteFromStart("Reading from destination");
            verifyFS.Read(verifyPart, 0, currentPartSize);
 
            ConsoleWriteFromStart("Verifying");
            bool successful = true;
            for (int i = 0; i < currentPartSize; i++)
                if (verifyPart[i] != part[i])
                {
                    successful = false;
                    break;
                }
            if (!successful)
            {
                sourceFS.Seek(currentPosition, SeekOrigin.Begin);
                destinationFS.Seek(currentPosition, SeekOrigin.Begin);
                verifyFS.Seek(currentPosition, SeekOrigin.Begin);
                ConsoleWriteFromStart("Fail");
            }
            else
            {
                lastBytes -= currentPartSize;
                ConsoleWriteFromStart("Successful");
                partCounter++;
            }
            Console.WriteLine();
        }
    }
    Console.WriteLine("Done!");
    return this;
}