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/

Arno
Mon Dec 01 06:06:08 CST 2003

In comp.sys.ibm.pc.hardware.storage David J Edgar <david@cd-yacht.demon.co.uk> 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

Roger
Mon Dec 01 06:19:59 CST 2003

http://support.microsoft.com/default.aspx?scid=kb%3Ben-us%3B328742
"David J Edgar" <david@cd-yacht.demon.co.uk> wrote in message
news:CDYC9514DE6B@cd-yacht.demon.co.uk...
> 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/
>
>

David
Mon Dec 01 06:48:40 CST 2003

"Roger Crawford" <rcrawford@nospam.scci.com> wrote in message
news:OE5JuZAuDHA.2380@TK2MSFTNGP09.phx.gbl...
> http://support.microsoft.com/default.aspx?scid=kb%3Ben-us%3B328742

Thanks, but my STT20000A is an IDE ATAPI unit.

Dave.

> "David J Edgar" <david@cd-yacht.demon.co.uk> wrote in message
> news:CDYC9514DE6B@cd-yacht.demon.co.uk...
> > 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/
> >
> >
>
>

David
Mon Dec 01 06:49:57 CST 2003

"Arno Wagner" <me@privacy.net> wrote in message
news:bqfarg$21i0s1$1@ID-2964.news.uni-berlin.de...
> In comp.sys.ibm.pc.hardware.storage David J Edgar
<david@cd-yacht.demon.co.uk> 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.

Roger
Mon Dec 01 06:59:21 CST 2003

Sorry I miss read the MS Article. I guess I should have been a little more
awake. I have not had much luck with the Seagate drive you are using either.
Seagate has been good with support but the drives fail it seems like almost
monthly. I have one site left with one and when it gets out of warrenty that
is going away. We have moved all of our customers over to Iomega USB Drives
and I don't have a bit of problems. I know not exactly what you wanted to
hear or your solution but that has been my luck with those units.

Roger Crawford
HTS

"David J Edgar" <david@cd-yacht.demon.co.uk> wrote in message
news:CDYC9564DF0B@cd-yacht.demon.co.uk...
> "Roger Crawford" <rcrawford@nospam.scci.com> wrote in message
> news:OE5JuZAuDHA.2380@TK2MSFTNGP09.phx.gbl...
> > http://support.microsoft.com/default.aspx?scid=kb%3Ben-us%3B328742
>
> Thanks, but my STT20000A is an IDE ATAPI unit.
>
> Dave.
>
> > "David J Edgar" <david@cd-yacht.demon.co.uk> wrote in message
> > news:CDYC9514DE6B@cd-yacht.demon.co.uk...
> > > 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
Mon Dec 01 10:35:00 CST 2003

In comp.sys.ibm.pc.hardware.storage David J Edgar <david@cd-yacht.demon.co.uk> wrote:
> "Arno Wagner" <me@privacy.net> wrote in message
> news:bqfarg$21i0s1$1@ID-2964.news.uni-berlin.de...
>> In comp.sys.ibm.pc.hardware.storage David J Edgar
> <david@cd-yacht.demon.co.uk> 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

bob
Mon Dec 01 15:58:37 CST 2003


"Arno Wagner" <me@privacy.net> wrote in message
news:bqfqjk$21rpg3$1@ID-2964.news.uni-berlin.de...
> In comp.sys.ibm.pc.hardware.storage David J Edgar
<david@cd-yacht.demon.co.uk> wrote:
> > "Arno Wagner" <me@privacy.net> wrote in message
> > news:bqfarg$21i0s1$1@ID-2964.news.uni-berlin.de...
> >> In comp.sys.ibm.pc.hardware.storage David J Edgar
> > <david@cd-yacht.demon.co.uk> 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

pschikor
Tue Dec 02 12:39:19 CST 2003

In article <CDYC9514DE6B@cd-yacht.demon.co.uk>,
David J Edgar <david@cd-yacht.demon.co.uk> 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/CertanceDrives/STT220000A-RDT-TechSpec.html


--

David
Wed Dec 03 05:59:03 CST 2003

"Paul F Schikora" <pschikor@steel.ucs.indiana.edu> wrote in message
news:bqim8n$evl$1@hood.uits.indiana.edu...
> In article <CDYC9514DE6B@cd-yacht.demon.co.uk>,
> David J Edgar <david@cd-yacht.demon.co.uk> 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/CertanceDrives/STT220000A-RDT-TechSpec.html
>

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

Dave.

--
David J Edgar
Cedaryacht Limited
Macclesfield UK.