what is stands for tape drive device file

[siva baskaran]

hi,


what is definition & differance for each device file.# iosncan -fnC tape
ksh: iosncan: not found
# ioscan -fnC tape
Class I H/W Path Driver S/W State H/W Type Description
=======================================================================
tape 1 0/0/0/3/1.3.0 stape CLAIMED DEVICE HP Ultrium 3-SCS
I
/dev/rmt/1m /dev/rmt/c3t3d0BEST
/dev/rmt/1mb /dev/rmt/c3t3d0BESTb
/dev/rmt/1mn /dev/rmt/c3t3d0BESTn
/dev/rmt/1mnb /dev/rmt/c3t3d0BESTnb
#

thanks
siva

[IT_2007]

/dev/rmt/c3t3d0BESTn --> No rewind

[spex]

Siva,

Take a look here:

http://forums1.itrc.hp.com/service/forums/questionanswer.do?threadId=630058

PCS

[Rick Garland]

Looking at the major/minor numbers you will see that are the same device, i.e., /dev/rmt/1m --> /dev/rmt/c3t3d0BEST. The cXtYdZ definition is being obsoleted.

The n is no rewind, the b is Berkely style, the 1m is rewind.

[Pete Randall]

The ones with a "b" on the end are Berkely style devices (rarely used). The ones with the "n" are no-rewind devices.


Pete

[Kofi ARTHIABAH]

A very good discription of the device names is given in man 7 mt available at:
http://docs.hp.com/en/B9106-90013/mt.7.html

Good luck

Kofi

[A. Clay Stephenson · Accepted solution]

The best description is found in the "man 7 mt" man page. It will describe the various options. I will also add that the tape device nodes are examples in which identical minor device numbers on different machines --- connected to exactly the same model tape drive on the machines --- can have very different behavior. Typically the minor the device numbers control rewind, no-rewind, Berkeley vs AT&T style but they can also control things like tape block size as well. In fact there are more options than can de encoded in the remaining bits of the minor device number. In the case of the tape driver, these bits actually form an index into an array that describes the tape device. Again, what this means is that identical minor device numbers (which would produce identical offsets into the array) might not have the same data stored at that array location. This is a long way of explaining why (unlike almost all other device nodes) that you always use the insf command to create tape device nodes rather than simply mknod. Insf will not only do the mknod but will also manipulate the driver control array entries as well.