[H-GEN] Linux Backup

[Tony Nugent]

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On Fri May 09 2003 at 17:38, Robert Stanford wrote:

> On Fri, 2003-05-09 at 08:27, Robert Stanford wrote:
> 
> > I was under the impression if the tape drive supported hardware
> > compression then dump used it by default?
> 
> Regarding this, somewhere in the back of my mind under the cobwebs and
> dust was a nagging recollection of reading somewhere about dump using
> hardware compression in tape drives by default, you had to actualy
> specify not using it. It's not is the current man pages, just back with
> other seldom used memories.[1]

With all the scsi-based tape backup units that I have used that were
capable of it, the only way I know of it enable hardware compression
was to use something like "mt -f /dev/nst0 defcompression 1"

Once hardware compression is enabled, it doesn't matter what dump
does... it uses whatever has been hardware set in the backup unit.
In that case, the data stream into the unit shouldn't be doing do
any compression (it becomes inefficient, as someone else pointed
out).

I've never had any problems using hardware compression, and on
average the result is around 60% of the original size.

> Robert Stanford <rob at rotapile.com>

Cheers
Tony

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