"JCB" wrote in message
news:31F97732-6D2A-4957-B269-D5B5F21309BB@microsoft.com...
> In Disk Properties, if Compress Drive is selected, is actual disk
> space
> conserved, or only apparent space? Also, is there an overhead burden
> associated with having a drive compressed in terms of slower
> reads/writes?
Compression ALWAYS incurs overhead. Why? Because CPU cycles are
expended to decompress the file for an application to actually use the
contents of that file and compression is required to save any changes
back into the compressed file/volume.
If the bulk of the files to be compressed are binary or image files,
compression won't do much to reduce their size and can actually increase
their size. Those types of files are already compressed (or very little
compressible).
Sounds like it is time to start looking at getting another drive or
replacing with a bigger one.
http://support.microsoft.com/kb/307987/en-us
As I recall, you cannot use volume (drive) compression on the partition
in which Windows is installed (i.e., you cannot compress the OS drive),
but you could compress your own folders or files there.