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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/ |
#2
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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 |
#3
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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/ |
#4
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"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/ |
#5
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"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. |
#6
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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 |
#7
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"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 |
#8
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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 -- |
#9
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"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. |
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