On Thu, Jun 19, 2003 at 04:14:38PM -0700, Jay Lessert wrote:
> On Thursday 19 June 2003 14:09, Ean Kingston wrote:
> >I'm using Solaris and, according to the documentation, it should not
> > be using hardware compression unless I specify the 'compress'
> > device (/dev/rmt/0cn) as opposed to the one I did use
> > (/dev/rmt/0n).
>
> I'm not sure what documentation you're referring to, but for every
> compression-capable drive I've ever used (DDS2, DDS3, DLT-4000,
> DLT-7000, DLT-8000, LTO-1) both the Solaris factory st driver and the
> tape-vendor-supplied st.conf default to the highest-possible density
> and compression factor.
Actually Jay the default can be specified in the st.conf file to match
any of the "l", "m", "h", or "u/c" entries and for 15 of the 49 entries
in my file the default does not correspond to the "u/c" mode.
device letter l m h u/c
0 1 2 3
ANRITSU ... 0x00, 0x02 ,0x03, 0x03, 1;
C3490 ... 0x00, 0x00, 0x00, 0x01, 2;
DLT ... 0x17, 0x18, 0x80, 0x81, 2;
DLT-data ... 0x80, 0x81, 0x82, 0x83, 2;
DLT7k-data ... 0x82, 0x83, 0x84, 0x85, 2;
Exa8500c ... 0x14, 0x15, 0x8C, 0x8C, 1;
Exa8505 ... 0x14, 0x15, 0x90, 0x8c, 1;
EXB-8500 ... 0x14, 0x15, 0x8C, 0x8C, 1;
Fujitsu_comp ... 0x00, 0x00, 0x00, 0x09, 1;
HP_half ... 0x01, 0x02, 0x03, 0xC3, 1;
HPT4 ... 0x45, 0x00, 0x00, 0x00, 0;
KENNEDY ... 0x01, 0x02, 0x03, 0x03, 1;
M4_DATA ... 0x01, 0x02, 0x06, 0x06, 1;
MT02 ... 0x84, 0x05, 0x05, 0x05, 1;
TAND-50G-VAR ... 0x30, 0x00, 0x00, 0x00, 0;
The last column specifies which of the 4 "densities" corresponds to the
"0" device (without l,m,h,c, or u).
>
> That is, I would be *very* surprised if the 0n device for your DLT1
> drive doesn't do "80GB" (compressed) mode.
I think the numeric values in columns 0 - 3 above are parameters passed
to the st driver when the drive is opened. A long time ago I saw some
HP DAT drive docs that said each bit in the values corresponded to a
parameter like compression ... You would need similar docs from the
drive manufacturer to decipher the numeric values.
--
Jon H. LaBadie jon AT jgcomp DOT com
JG Computing
4455 Province Line Road (609) 252-0159
Princeton, NJ 08540-4322 (609) 683-7220 (fax)
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