SUMMARY: Device for 20-40Gb 8mm tape drive

From: Sergio Edo. Miranda (
Date: Mon Mar 16 1998 - 16:32:47 CST

Here is the original question:
 I have a 20-40 Gbyte 8mm tape drive installed in Ultra Enterprise 3000
 (Solaris 2.6)
 I'm not sure if i have to use another device for compression

i'm using /dev/rmt/0cn with completly success
Here are the answers, thanks everybody

ANS 1:
From: "Kevin P. Inscoe" <>
Use /dev/rmt/0cn and make sure you have patch 103857-12 installed to
make the compression work with the driver. Also you will need to
update /kernel/drv/st.conf with the following lines:

    "EXABYTE EXB-8900","EXB-8900 Mammoth", "mam-data";

mam-data =1,0x29,0,0xce39,4,0x7f,0x7f,0x7f,0x7f,0;

[end of st.conf lines]

These were given me by Sun Engineering and they are working under
Solaris 2.5.1 HW 4/97. HW 8/97 may have avoided the st.conf changes
but you will still need the patch. mt status will also report the
device as being a EXB-8500 when in fact it is a EXB-8900. The 103857-12
patch will also fix this. After changing st.conf and installing the
patch you will need to boot -r to reconfigure the st driver. If you
are running Solaris 2.6 you will not need the patch but check the
st.conf file for correctness expecially mam-data.


ANS 2:
I would bet that the device names with h and c in them do
compression, but I would hope for some kind of documentation.
You can always perform test cases.

ANS 3:
From: Jim McVey <>
Try /dev/rmt/0cn or /dev/rmt/0hn.
ANS 4:
From: David Harte <>
If you look in /dev/rmt

  there are all the devices 0n 0c 0nc 0nbc etc etc..
 anyway bacially density is one factor and can be c h l m u, c is for
compression there is also h l m u high low medium and ultra.
   n for no rewind
and b for bsd behaviour

 so you probably just want /dev/rmt/0c

ANS 5:
From: Bismark Espinoza <bismark@alta.Jpl.Nasa.Gov>
Try 0cn or 0hn .

ANS 6:
From: Peter Bestel <>
Since this is a non-standard drive, the default device behaviour
shall depend on the entry you've placed into /kernel/drv/st.conf.
There are multiple compression settings available for each drive
and then a default one which is to be set (see the st(7D) manual

So, normally I'd be using /dev/rmt/0c, as the compression setting
isn't always the default to be applied to the device. What does
your entry in the st.conf file look like for this drive?


Sergio Edo. Miranda
Grupo de Ingenieria - CEC
Universidad de Chile

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