is vdump compressing data even when I don't ask it to?

From: <speakmaj_at_mskcc.org>
Date: Thu, 21 Nov 2002 09:21:46 -0500

     Hi all
     
     I find I can vdump a 108 GB fileset onto a TL891 library with a
     40/80GB TZ89 drive and it will stick the whole lot on one tape without
     asking for a new tape.
     
     This is okay, even gratifying, as long as it's all really there. But
     I don't specify compression (-C) , or a blocking factor (-b) , on the
     vdump, and most of the data in this fileset is compressed or gzipped
     already. Is vdump just doing some compression for me anyway?
     
     The 'man vdump' says:
     
     "Under normal usage, the vdump command uses a small amount of
     additional space on the storage device, typically less than 1 percent,
     when a fileset is backed up."
     
     But clearly this is not my experience...
     
     I am doing a 'vdump -D' on 4.0E. Will summarize.
     
     Thanks
     
     John Speakman
     Memorial Sloan-Kettering Cancer Center
Received on Thu Nov 21 2002 - 14:22:24 NZDT