[sllug-members]: Encrypted backup tapes

[Lamont Peterson]

On Thursday 11 January 2007 04:21pm, Andrew GIlmore wrote:
> On Thu, 2007-01-11 at 14:06 -0700, James Knowles wrote:
> > > ...  compression as a way to strengthen a cipher ...
> >
> > Absolutely.
> >
> > The only reason to perform compression on backups is to, well,
> > /compress/, i.e. squeeze more onto a tape.
>
> Exactly, although I believe compressing before encryption may be a waste
> of time, since as other folks have commented, many commandline
> encryption tools compress _in the process of encryption!_

In my case, I also ran the command I mentioned earlier in this thread once 
without the "gzip -9" in the pipeline.  The resulting file was 2.05GB on 
2.5GB of source data.  With "gzip -9", it was 1.6GB.

BTW, all the extra computational overhead of gzip with higher compression 
values (such as with "-9") is in the compression side.  In fact, 
decompressing a file that was compressed with "gzip -9" requires much less 
processing than decompressing a file that was compressed with, 
say, "gzip -3".
-- 
Lamont Peterson <lamont at gurulabs.com>
Senior Instructor
Guru Labs, L.C. [ http://www.GuruLabs.com/ ]

NOTE:  All messages from this email address should be digitally signed with my
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