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Re: dat 72 usb compression

 
stefano marcotulli
Occasional Contributor

dat 72 usb compression

Hi,
i've a dat 72 usb drive with media c8010a 72GB compression, connected a single server win2003.
when running nt backup the media backup max 36GB, no more (with nt backup, compression is default enable).

i've tested with hp L&TT tools with compression 2:1 but write only 36GB. attach files.
Which is the problem ?

I hope to find a solution on it.
regards
Stefano Marcotulli


3 REPLIES 3
thomasr
Respected Contributor

Re: dat 72 usb compression

If I understand you correctly, you used Library and Tape Tools to send 2:1 data to the tape drive, and it still did not fit more than 36GB? In that case, you might want to see http://support.microsoft.com/kb/827475/en-us . Or, try a third-party backup program like HP's Data Protector Express (a free single-server license comes with most all standalone HP tape drives).

If I misunderstood, and you have not sent known compressible data to the drive, then:

A tape drive can only compress data if the data has lots of "patterns" in it. Data that has already been compressed (like jpeg, mpeg, powerpoint) has had the patterns stripped out of it. Data that is random (encrypted data, the digits of pi, etc.) has no patterns and can not be compressed.

What you can do with Library and Tape Tools is measure how compressible the data you're backing up is. My guess is that it is not compressible, and the tape drive can't "make" it compressible.

Please let me know if the Microsoft article helps, or if not, the results of the L&TT compression test.
--
Liberty breeds responsibility; Government breeds dependence
stefano marcotulli
Occasional Contributor

Re: dat 72 usb compression

Hi thomasr,

thanks for having responded, now see if the link MS I will find it useful.
in the attached file you'll notice that the compression is not the media. this test I did after checking in on that ntbackup backup 55GB on average saves only 36GB.

Greetings
Stefano
stefano marcotulli
Occasional Contributor

Re: dat 72 usb compression

no this link not help me, because my so is windows 2003 std r2.

thanks anyway