c:\test>perl -E"printf qq[%014d: %014d\n], $_, $_ for 1..262144" >junk.dat

c:\test>dir junk.dat
10/04/2010  11:06         8,388,608 junk.dat

c:\test>perl -MDevel::Size=total_size 
-E"local$/; my %h = split ': ', <>; print total_size \%h;" junk.dat
12489744