topic /dev/rmt/0???? in Operating System - HP-UX

/dev/rmt/0????

Stephen Badgett — Wed, 07 Jul 2004 19:09:14 GMT

What does each of these devices represent?

0m
0mb
0mn
0mnb
1m
1mb
1mn
1mnb
c0t3d0BEST ...

From what I have seen ...

/dev/rmt/0m -- rewind the tape to the start after any command

/dev/rmt/0mn -- no-rewind leave the tape at the position where the old command left off

Steve

Re: /dev/rmt/0????

Sundar_7 — Wed, 07 Jul 2004 19:14:39 GMT

Hi Steve,

Run lssf command against the device files - will tell you the characteristics of each of the device files

# lssf /dev/rmt/0m
stape card instance 3 SCSI target 3 SCSI LUN 0 at&t best density available at address 0/4/0/0.3.0 /dev/rmt/0m
# lssf /dev/rmt/0mn
stape card instance 3 SCSI target 3 SCSI LUN 0 at&t no rewind best density available at address 0/4/0/0.3.0 /de
v/rmt/0mn
# lssf /dev/rmt/0mnb
stape card instance 3 SCSI target 3 SCSI LUN 0 berkeley no rewind best density available at address 0/4/0/0.3.0
/dev/rmt/0mnb
#

b = confirms to the berkeley standard - by default it is AT&T

c0t3d0BEST = uses best density available (software compression) - Same as 0m - no big difference.

Re: /dev/rmt/0????

Con O'Kelly — Wed, 07 Jul 2004 19:15:06 GMT

Hi Steve

You'll find a full explanation of the what each device file means in the man page:
# man mt

Cheers
Con

Re: /dev/rmt/0????

Con O'Kelly — Wed, 07 Jul 2004 19:15:54 GMT

sorry should have said:
# man 7 mt

Cheers
Con

Re: /dev/rmt/0????

edwin hamers — Fri, 09 Jul 2004 04:18:06 GMT

Hi,

I was lately at a HP advanced Administrator Course, and there they adviced to use only the /dev/rmt/c0t3d0BEST device.

Re: /dev/rmt/0????

Stephen Badgett — Fri, 09 Jul 2004 11:05:12 GMT

Hello Edwin,

Thank you for your response.

I was using different device files with lots of success. The /dev/rmt/1nm type is great when I do not want the tape to rewind when a command has completed. Using this method I can continue a store later if needed and also store different versions of the same file on the same tape, that is a fine feature. The other device is useful when I just need to do one command and have it at BOT when done with that command, WOW I like that too.

Now with the device /dev/rmt/c0t3d0BEST is it going to know to rewind or not rewind when a store type command is giving, default being rewind? We have c0t0d0BESTnb and I guess that would be a NO-REWIND Berkley and c0t0d0BESTb would be REWIND Berkley, correct?

Steve

Re: /dev/rmt/0????

Sundar_7 — Fri, 09 Jul 2004 11:10:14 GMT

Steve,

c0t0d0BESTnb = No-rewind Berkeley and uses the best compression possible

c0t0d0BESTb = Rewind Berkeley and again uses the best compression possible

-- Sundar.

Re: /dev/rmt/0????

RAC_1 — Fri, 09 Jul 2004 11:18:38 GMT

If you do a ls -il on those files, you will see that the inode is same for most of them.
Like for 0m and for BEST.

So they are same, represeted in different way.

Anil

Re: /dev/rmt/0????

Stephen Badgett — Fri, 09 Jul 2004 11:51:52 GMT

YES

Thank you Anil that is just one more great answer and helps a great deal

Thank you

Steve