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Capacity DAT8e

Armin Rösch
Occasional Visitor

Capacity DAT8e

doing backup i cant choose compress or net. While bkp the soft shows HARDWARE compressing. I would like to choose up 2:1 as give by specs.
(using DDS2 tape)
Any idea
Thanks Armin
Jan Klier
Respected Contributor

Re: Capacity DAT8e

I'm not sure that I understand what you're trying to do??

With tape drives you can choose compression on or off. You cannot choose any specific ratio - what the spec means with 2:1 is that on an average data pattern hardware compression in the drive can achieve a 2:1 compression ratio. But that is purely an average - highly compressible data may achieve even higher ratios, while already compressed image files may even expand.
Armin Rösch
Occasional Visitor

Re: Capacity DAT8e

Hi Jan,

Thanks for replay!
By soft it offers you the choice compression or not. If I choose YES the the protocol shows requested compression switched OFF because HARDWARE compression of the drive used. What I do not find is where to enable or disable this compression?
By the way do you know a way to "see" how much free space is on a tape?
Thank you?


Armin R??sch
David Ruska
Honored Contributor

Re: Capacity DAT8e

> What I do not find is where to enable or disable this compression?

Compression is controlled by switches on the drive. Newer external drives (e.g. DAT40) have a hole in the bottom to access the switches. The older boxes require removal of the case cover and the drive to access the switches.

There are 8 configuration switches. Switches 1 & 2 control compression.

With both switches on, compression is enabled by default, but the host can change it. Set switch 2 to off, and the host cannot change it. Set switch 1 to off, and compression is disabled. Again, switch determines if the host can change it.

The default is both switches on, which enables compression, but allows the host to override it. If you want hardware compression off always, then set both switches off.

It's all explained in this document as well:
The journey IS the reward.