Regarding tar and split

[Sean Zimmermann <svz90@pipeline.com>]

Hello.

I frequently work with large tar archives that often need to be split into
smaller pieces. Up until now, I've used tar -m to create multi-part archives. I
recently read that I can use split to do the same thing. Is there an advantage 
or disadvantage to using split over tar -m?

Also, is there some way to index a large tar file, so if I want to extract a 
file at the end of a large archive, tar doesn't have to seek through the entire
archive to get the file?

Thank you for any help.

Regards,
Sean