Seagate STT20000A - Problems with compression

Hi,

I've got a problem using hardware compression with a Seagate STT20000A IDE
Travan TR-5 tape drive.

I am using the backup program that is native to Windows 2000 Server and
can't get more than 10GB on a tape. These tapes should handle up to 20GB of
data if compressed. I have selected the 'use hardware compression if
available' option but the backup fails when 10GB has been written.

Has anybody else had this problem?

Seagate STT20000A (Firmware 8a51), Windows 2000 Server (SP4), Windows
Backup.

Dave.

--
David J Edgar
Cedaryacht Limited
Macclesfield UK.
http://www.omega-environment.com/

In comp.sys.ibm.pc.hardware.storage David J Edgar wrote:
Hi,

I've got a problem using hardware compression with a Seagate STT20000A IDE
Travan TR-5 tape drive.

I am using the backup program that is native to Windows 2000 Server and
can't get more than 10GB on a tape. These tapes should handle up to 20GB of
data if compressed. I have selected the 'use hardware compression if
available' option but the backup fails when 10GB has been written.

Has anybody else had this problem?

Seagate STT20000A (Firmware 8a51), Windows 2000 Server (SP4), Windows
Backup.

There is a mathematical limit to compressibility, called entropy.
You cannot compress better that the entropy contained, no matter what
algorithm. In practice, already compressed data can usually not
be compressed further. That includes video and audio that is
compressed. Since hardware compression can use little memory, it
usually does significantly worse than software compression tools.
It sometimes even enlarges pre-compressed data.

Arno
--
For email address: lastname AT tik DOT ee DOT ethz DOT ch
GnuPG: ID:1E25338F FP:0C30 5782 9D93 F785 E79C 0296 797F 6B50 1E25 338F
"The more corrupt the state, the more numerous the laws" - Tacitus

http://support.microsoft.com/default...en-us%3B328742
"David J Edgar" wrote in message
...
Hi,

I've got a problem using hardware compression with a Seagate STT20000A IDE
Travan TR-5 tape drive.

I am using the backup program that is native to Windows 2000 Server and
can't get more than 10GB on a tape. These tapes should handle up to 20GB
of
data if compressed. I have selected the 'use hardware compression if
available' option but the backup fails when 10GB has been written.

Has anybody else had this problem?

Seagate STT20000A (Firmware 8a51), Windows 2000 Server (SP4), Windows
Backup.

Dave.

--
David J Edgar
Cedaryacht Limited
Macclesfield UK.
http://www.omega-environment.com/

"Roger Crawford" wrote in message
...
http://support.microsoft.com/default...en-us%3B328742

Thanks, but my STT20000A is an IDE ATAPI unit.

Dave.

"David J Edgar" wrote in message
...
Hi,

I've got a problem using hardware compression with a Seagate STT20000A
IDE
Travan TR-5 tape drive.

I am using the backup program that is native to Windows 2000 Server and
can't get more than 10GB on a tape. These tapes should handle up to 20GB
of
data if compressed. I have selected the 'use hardware compression if
available' option but the backup fails when 10GB has been written.

Has anybody else had this problem?

Seagate STT20000A (Firmware 8a51), Windows 2000 Server (SP4), Windows
Backup.

Dave.

--
David J Edgar
Cedaryacht Limited
Macclesfield UK.
http://www.omega-environment.com/

"Arno Wagner" wrote in message
...
In comp.sys.ibm.pc.hardware.storage David J Edgar
wrote:
Hi,

I've got a problem using hardware compression with a Seagate STT20000A
IDE
Travan TR-5 tape drive.

I am using the backup program that is native to Windows 2000 Server and
can't get more than 10GB on a tape. These tapes should handle up to 20GB
of
data if compressed. I have selected the 'use hardware compression if
available' option but the backup fails when 10GB has been written.

Has anybody else had this problem?

Seagate STT20000A (Firmware 8a51), Windows 2000 Server (SP4), Windows
Backup.

There is a mathematical limit to compressibility, called entropy.
You cannot compress better that the entropy contained, no matter what
algorithm. In practice, already compressed data can usually not
be compressed further. That includes video and audio that is
compressed. Since hardware compression can use little memory, it
usually does significantly worse than software compression tools.
It sometimes even enlarges pre-compressed data.

Arno
--
For email address: lastname AT tik DOT ee DOT ethz DOT ch
GnuPG: ID:1E25338F FP:0C30 5782 9D93 F785 E79C 0296 797F 6B50 1E25 338F
"The more corrupt the state, the more numerous the laws" - Tacitus




Thanks, but my problem is that no compression operation is attempted!

Dave.

In comp.sys.ibm.pc.hardware.storage David J Edgar wrote:
"Arno Wagner" wrote in message
...
In comp.sys.ibm.pc.hardware.storage David J Edgar
wrote:
Hi,

I've got a problem using hardware compression with a Seagate STT20000A
IDE
Travan TR-5 tape drive.

I am using the backup program that is native to Windows 2000 Server and
can't get more than 10GB on a tape. These tapes should handle up to 20GB
of
data if compressed. I have selected the 'use hardware compression if
available' option but the backup fails when 10GB has been written.

Has anybody else had this problem?

Seagate STT20000A (Firmware 8a51), Windows 2000 Server (SP4), Windows
Backup.

There is a mathematical limit to compressibility, called entropy.
You cannot compress better that the entropy contained, no matter what
algorithm. In practice, already compressed data can usually not
be compressed further. That includes video and audio that is
compressed. Since hardware compression can use little memory, it
usually does significantly worse than software compression tools.
It sometimes even enlarges pre-compressed data.

Arno
--
For email address: lastname AT tik DOT ee DOT ethz DOT ch
GnuPG: ID:1E25338F FP:0C30 5782 9D93 F785 E79C 0296 797F 6B50 1E25 338F
"The more corrupt the state, the more numerous the laws" - Tacitus




Thanks, but my problem is that no compression operation is attempted!

How do you know that? Just because it fails after 10GB does not mean
it does not try to compress. Or is there some other way you can tell?
If your data is pre-compressed, there is no way in this universe
you can get any significant compression on it.

Maybe it tries to compress but does not succeed and therefore writes
the data uncompressed.

Arno
--
For email address: lastname AT tik DOT ee DOT ethz DOT ch
GnuPG: ID:1E25338F FP:0C30 5782 9D93 F785 E79C 0296 797F 6B50 1E25 338F
"The more corrupt the state, the more numerous the laws" - Tacitus

"Arno Wagner" wrote in message
...
In comp.sys.ibm.pc.hardware.storage David J Edgar
wrote:
"Arno Wagner" wrote in message
...
In comp.sys.ibm.pc.hardware.storage David J Edgar
wrote:
Hi,

I've got a problem using hardware compression with a Seagate
STT20000A
IDE
Travan TR-5 tape drive.

I am using the backup program that is native to Windows 2000 Server
and
can't get more than 10GB on a tape. These tapes should handle up to
20GB
of
data if compressed. I have selected the 'use hardware compression if
available' option but the backup fails when 10GB has been written.

Has anybody else had this problem?

Seagate STT20000A (Firmware 8a51), Windows 2000 Server (SP4), Windows
Backup.

There is a mathematical limit to compressibility, called entropy.
You cannot compress better that the entropy contained, no matter what
algorithm. In practice, already compressed data can usually not
be compressed further. That includes video and audio that is
compressed. Since hardware compression can use little memory, it
usually does significantly worse than software compression tools.
It sometimes even enlarges pre-compressed data.

Arno
--
For email address: lastname AT tik DOT ee DOT ethz DOT ch
GnuPG: ID:1E25338F FP:0C30 5782 9D93 F785 E79C 0296 797F 6B50 1E25
338F
"The more corrupt the state, the more numerous the laws" - Tacitus




Thanks, but my problem is that no compression operation is attempted!

How do you know that? Just because it fails after 10GB does not mean
it does not try to compress. Or is there some other way you can tell?
If your data is pre-compressed, there is no way in this universe
you can get any significant compression on it.

Maybe it tries to compress but does not succeed and therefore writes
the data uncompressed.

Arno
--
For email address: lastname AT tik DOT ee DOT ethz DOT ch
GnuPG: ID:1E25338F FP:0C30 5782 9D93 F785 E79C 0296 797F 6B50 1E25 338F
"The more corrupt the state, the more numerous the laws" - Tacitus


Check to see if your drive is already compressed. If it is, you will not
get compression on the tape

In article ,
David J Edgar wrote:
Hi,

I've got a problem using hardware compression with a Seagate STT20000A IDE
Travan TR-5 tape drive.

I am using the backup program that is native to Windows 2000 Server and
can't get more than 10GB on a tape. These tapes should handle up to 20GB of
data if compressed. I have selected the 'use hardware compression if
available' option but the backup fails when 10GB has been written.

Has anybody else had this problem?

Seagate STT20000A (Firmware 8a51), Windows 2000 Server (SP4), Windows
Backup.

This drive is not capable of harware compression. The circuitry is just
not there. You must use software compression to get 10GB per tape.

http://www.certance.com/products/Cer...-TechSpec.html


--

"Paul F Schikora" wrote in message
...
In article ,
David J Edgar wrote:
Hi,

I've got a problem using hardware compression with a Seagate STT20000A
IDE
Travan TR-5 tape drive.

I am using the backup program that is native to Windows 2000 Server and
can't get more than 10GB on a tape. These tapes should handle up to 20GB
of
data if compressed. I have selected the 'use hardware compression if
available' option but the backup fails when 10GB has been written.

Has anybody else had this problem?

Seagate STT20000A (Firmware 8a51), Windows 2000 Server (SP4), Windows
Backup.

This drive is not capable of harware compression. The circuitry is just
not there. You must use software compression to get 10GB per tape.


http://www.certance.com/products/Cer...-TechSpec.html


Thanks - not the answer I wanted but at least I know now.

Dave.

--
David J Edgar
Cedaryacht Limited
Macclesfield UK.