download large files from a remote server, how to test for correct file and delivery?

Question

There are 2 servers that are geographically very far from each other.

One server does file processing, then saves the processed file in a directory:

c:\processed\

Files can be 100-1GB in size.

The 2nd server is to download these files.

What techniques can I use to check if the file correctly downloaded?

Is a checksum all I need to do? will it hash according to the contents of the file or just the file attributes? (or what is best practise)
If the file is 1GB, will creating the checksum take a long time?

Answer 1

Checksum is fine to make sure that the downloaded data matches the source data. For a discussion of making it fast, see http://stackoverflow.com/questions/1177607/what-is-the-fastest-way-to-create-a-checksum-for-large-files-in-c.