Further to the fascinating discussion on zipping mainframe SAS data, I have found something that defies explanation....
My "transportable" SAS dataset will download from the mainframe at 3,408,024 bytes/second
My compressed dataset will download from the mainframe at 421,011 bytes/second.
The compressed file is a zipped copy of the SAS file in transportable format,
Both use the same CONNECT session. Both use PROC DOWNLOAD. The uncompressed file uses a DATA=xxx OUT=yyy and the zipped file uses INFILE=zzz OUTFILE=bbb.
Why are they different? I have been assured that (repeatedly) that there is no hardware compression. They bytes in the uncompressed file aren't smaller than in the compressed file (grins). Even though the zipped file downloads faster, the unzipped file downloads at about 8x the speed of the zipped file.
We ran into a similar situation. It was caused by our firewall caching and uncompressing the zipped file in its efforts to look for viruses. Is there a firewall in the network path? We had to disable virus scanning on that network path.