Copying Large Files Between Sites

I got a call recently from a tech at a remote site that said that our Windows 7 x64 image was bombing out at 16%.  We did the usual “image another PC” and “bounce the server”, but the results were the same.  I compared the file sizes and they were the same and the WIM file opened just fine with 7Zip.  However, when I ran Hasher against my WIM file at corporate and the other sites, each one had a different SHA-1/CRC/MD5 value.  Oops!  I re-copied the file overnight and then verified with Hasher again and we had a match.   I did some research on how I can verify and repair large files.  I found Multipar.  Parity files have long be used on USENET for repairing large files transferred over the Internet.  I just picked 1% for data redundancy and created the PAR file.  For an 8GB image, that works out to be about an 80MB file.  Using this 80MB file, I was able to verify and repair the 8GB file at the remote site.

I went through the rest of the images and some of them matched up and some of them didn’t! Using the parity files created for each image, I was able to repair them all over remote desktop at the remote sites.  I’ve been doing this overnight copy for years and it was never a problem.  Of course, my images use to be < 2GB and now they are about 8GB each!

– Soli Deo Gloria