DAT Drive: Hardware compression HOWTO

DAT Drive: Hardware compression HOWTO

Post by Dan Smit » Mon, 14 May 2001 08:26:57



I have a Seagate Scorpion 8 DAT tape drive.  I need to turn on
hardware compression, but I can't figure out how.  Can someone help me
out?  I've tried "mt -f /dev/st0 compression on" and "mt -f /dev/st0
setdensity 0x24" but nothing seems to help.  It is a DDS-2 drive (8GB)
that is stuck on DDS-1 (2-GB) mode.

I'm using Tapeware for linux, but that shouldn't matter.  It can tell
me that compression is off, but can't do much about it...

Thanks!

--Dan

 
 
 

DAT Drive: Hardware compression HOWTO

Post by Juergen Pfan » Mon, 14 May 2001 15:01:10



> I have a Seagate Scorpion 8 DAT tape drive.  I need to turn on
> hardware compression, but I can't figure out how.  Can someone help me
> out?  I've tried "mt -f /dev/st0 compression on" and "mt -f /dev/st0
> setdensity 0x24" but nothing seems to help.  It is a DDS-2 drive (8GB)
> that is stuck on DDS-1 (2-GB) mode.

I don't know that particular Seagate model, but check its manual
for jumpers or DIP-switches controlling compression.
The way I see it is, if you disabled HW compression by jumper,
you cannot control it by the mt tool - but if enabled, then mt
should have control to turn it off on demand.
At least that's the way my Archive Python DDS-1 and the Sony DDS-3
drive work, as well as some HPs in the office.
BTW : with my version of mt, it's "... datcompression 0" to disable,
1 just to print the compression status, and any other number to
enable.
About the media : Normally, you don't need to set densities for
the different DDS media manually - this should be auto-sensed
by the "Media Recognition System" of the tape cartridges.
With an older distro - and hence old mt version - "mt setdensity"
also doesn't seem to work, but the Sony obviously adjusts that
automatically. I verified already that you can write 4 GB (native)
to DDS-2 and some 12 GB to DDS-3 media. Thus, it's only a "cosmetic"
display issue, at least fo me.

HTH

Juergen

 
 
 

DAT Drive: Hardware compression HOWTO

Post by Gary Smit » Fri, 18 May 2001 22:05:03


Can anyone Help me.

I have a DDS3 HP tape drive and I want to find out how do I mount the tape
to allow viewing the contents of it?  The backup process Tar's up a file and
puts it on /dev/st0 but I cannot seem to veryify the contact of the tape
once complete. I get a file with the file names that have been copied from
the backupscript.
What File system should be specified when mounting this type of tape?
Also, can one file be extracted from the tar file, by specifying its file
name, or do you have to specify its full original path prior to taring?

Any help appreciated.

Thanks



> > I have a Seagate Scorpion 8 DAT tape drive.  I need to turn on
> > hardware compression, but I can't figure out how.  Can someone help me
> > out?  I've tried "mt -f /dev/st0 compression on" and "mt -f /dev/st0
> > setdensity 0x24" but nothing seems to help.  It is a DDS-2 drive (8GB)
> > that is stuck on DDS-1 (2-GB) mode.

> I don't know that particular Seagate model, but check its manual
> for jumpers or DIP-switches controlling compression.
> The way I see it is, if you disabled HW compression by jumper,
> you cannot control it by the mt tool - but if enabled, then mt
> should have control to turn it off on demand.
> At least that's the way my Archive Python DDS-1 and the Sony DDS-3
> drive work, as well as some HPs in the office.
> BTW : with my version of mt, it's "... datcompression 0" to disable,
> 1 just to print the compression status, and any other number to
> enable.
> About the media : Normally, you don't need to set densities for
> the different DDS media manually - this should be auto-sensed
> by the "Media Recognition System" of the tape cartridges.
> With an older distro - and hence old mt version - "mt setdensity"
> also doesn't seem to work, but the Sony obviously adjusts that
> automatically. I verified already that you can write 4 GB (native)
> to DDS-2 and some 12 GB to DDS-3 media. Thus, it's only a "cosmetic"
> display issue, at least fo me.

> HTH

> Juergen

 
 
 

DAT Drive: Hardware compression HOWTO

Post by Joshua Baker-LePai » Fri, 18 May 2001 22:26:51



> I have a DDS3 HP tape drive and I want to find out how do I mount the tape
> to allow viewing the contents of it?  The backup process Tar's up a file and
> puts it on /dev/st0 but I cannot seem to veryify the contact of the tape
> once complete. I get a file with the file names that have been copied from
> the backupscript.
> What File system should be specified when mounting this type of tape?
> Also, can one file be extracted from the tar file, by specifying its file
> name, or do you have to specify its full original path prior to taring?

Did you do *any* looking on your own?  This is about as FA as a FAQ can get.

You don't mount a tape -- it's not a block device.  To list the contents
of the tar on the tape (just as you would a tar file on disk), usr 'tar t',
as in 'tar tf /dev/nst0'.

--
Joshua Baker-LePain
Department of Biomedical Engineering
Duke University