I've been working on this for a while and decided to see if anyone else here had this same issue. I'm trying to ftp a file from a mainframe (OS390) to Solaris. Obviously this is easily done, however the file is somehow being stripped of data in comparison to the way we transfer the file via a reel tape. The data coming from the tape is 93M larger than the file via ftp. Does anyone have any ideas why this is happening? 
I know nothing about mainframes, so don't flame me too bad if I'm way off. But I do remember an issue with files from a mainframe being in ebcdic format which Solaris doesn't handle properly.
There are options on the dd command which let you convert files between different formats. I checked the man page for dd and it shows that converting ebcdic to ascii is one of the options it will handle. Maybe you could take a look at that and see if it will help.
could be a difference between the filesystems. don't know which fs os390/vms/host use but there is also a small diff between solaris' ufs and windows ntfs.... they are using diff blocksizes.. so if you have a bs of 512byte and you want to save a 1700bytes file you need 4 blocks... well the file is still 1700bytes but you will need 2048bytes in the filesystem. so if there are more files with such a difference the disk usage grows up.......
gP
My guess: You need to transfer the file in binary mode rather than ascii mode.
MVS may have channel control words embedded in files -- at the beginning of every line. So if you have 250,000 lines you have an extra 500,000 bytes.
MVS also pads fixed length record files out to the record boundary.
I dunno what you're dealing with, but get into FileAid and find out for yourself.
thanks, I will look into it.. I may have to rewrite the program that deblocks the MVS data and converts it to ascii. thanks for all of your inputs.