On Sun, Mar 12, 2006 at 01:03:49PM -0500, Jon LaBadie wrote:
> On Sun, Mar 12, 2006 at 11:59:03AM -0500, stan wrote:
> > I had 2 Amanda instances, one hosted on FreebSD, and the other on and
> > Progeny Linux machine. I lost the root disk on the Linux server, and I'm
> > building a replacement machine.
> >
> > Looking at the script that is run on the FreebSD machine I see that I do a
> > "nt comp off" to make certain that compression is off on the tape drive,
> > before I start the Amanda run.
> >
> > I'm building the replacement machine on an Ubuntu Linux machine, and looking
> > at the man page for mt it does not seem to support this command.
> >
> > What are people with Linux hosts using to accomplish making certain that the
> > tape drive is in uncompressed mode? I'm using an Ultrim 3 (HP) drive for
> > the replacement machine, as well as (for recovery purposes) the existing
> > Quantum DLT80 drive, if it matters. The DLT drive has front panel buttons
> > to control this, but the U3 drive does not BTW.
>
> While hardly a novice overall, I am a novice to tapes on linux.
> Keep that in mind when reading my comments.
>
> For the quantum, you say used only for recovery, it doesn't matter.
> The drive sets itself to whatever is on the tape.
>
> For the Ultrium 3 (lucky you, my taping sessions would take about
> 2 minutes on that drive :))
I'll fell lucky when/if my tapetype run on this drive finally finishes :-)
>it actually does not hurt to leave
> the compression mode on. If set to compression mode on, the
> drives compression routines sense what it can and can't compress.
> Anything that doesn't compress is left alone. So you can have
> your cake and eat it too :) If you have some DLEs you don't
> want to software compress, then the drive will help you by using
> hardware compression. For your software compressed DLEs, the
> drive will pass them to tape as is. So you can set your tape
> size to the native 400GB (or higher if you have some uncompressed
> DLEs) and still leave compression on.
>
> If you still want control of the drives on your new linux,
I do, consider it a character falw :-)
> be aware
> that different distributions handle the problem in different ways.
> Some have an mt with options for setting it. Some have ways to
> specify a default (??defcompression??) as well as block sizes etc.
> that take place on boot. I 'think' a wave of the future is those
> that use the stinit command at boot. Controlled by a stinit.def
> file, it sets up 4, not 1 device name for your drive. So besides
> just {n}st0, you also get {n}st0{[lma]}. In the stinit.def file
> you specify what properties the driver should set each time that
> particular device is opened. So I set my st0l (l for low :)
> device to no compression and 32Kb blocksize and use that for
> amanda. With such a fast drive you may want to experiment with
> non-amanda-standard block sizes. The standard 32Kb may degrade
> the drive's performance.
Mmm, I'm using Ubuntu.
Hmm. doing an apt-cache search on stinit reveals a package called
mt-st. Which it seems brings in stinit, and (drum roll) a version
of mt that understands (at least the man page references) a
compression off operation.
Looks like just the ticket! Thanks for the pointer.
As usual there is more than one way to do this in Linux.
BTW, this machine would be running Solaris 10, as it's
an brand new Ultra 40, but I nvere managed to come up with
a working combination of SCSI card, tape drive, and Solaris
driver. I'm really disapointed, as I've got a whole bunch
of machines that will over the next coule of years migrate to
Soalris 10, and I was looking foward to using this machien
as a learning tool for that. Oh, well.
Thanks, again.
--
U.S. Encouraged by Vietnam Vote - Officials Cite 83% Turnout Despite Vietcong
Terror
- New York Times 9/3/1967
|
