aix 4.2 : using dd of=/dev/rmt0 producing error Post: 302331255

Sponsored Content

Operating Systems AIX aix 4.2 : using dd of=/dev/rmt0 producing error Post 302331255 by Browser_ice on Sunday 5th of July 2009 08:08:24 AM

07-05-2009

Registered User

Quote:

Originally Posted by bakunin

First off, (depending on the type of your tape drive) you have a pretty good chance of not needing any compress at all because most of the IBM tape drives have a hardware compression built in. If you send a compressed stream down to the tape drive it will be compressed a second time which will usually make the file a little bigger (because of the second compression overhead adding), not smaller.

Second, even if it is justified using "compress" in your case, you probably have to add "if=-" to the "dd" command. AFAIK "dd" doesn't use stdin per default for incoming data. It also might be necessary to state the blocksize. Use "bs=<some number>" in this case to state the block size in bytes.

A third reason might be that you have to adress the tape drive with another device number, maybe "/dev/rmt0.1". Have a look in the manual for the meaning of the minor device numbers with tape drives.

I do not recognize your first statement "change tape block_size=512", usually this is accomplished using the "tctl" command, alternatively use the "chdev" command on "/dev/rmtn".

I hope this helps.

bakunin

I know the client's tape drive are using built in compression. But the problem is that is taking toooo looonnnggggg. Backing up a 10Gb folder's content takes 5 hours. The procedures we use to do the backups (10 database backups between averaging 8Gb spreaded amongst 5 servers with each only one tape drive) have us verify the tapes after we have done the TAR backups. Do do all of this takes 18 hours ! I want to reduce this time as much as possible with 2 ways where one way is using compression before putting on tapes. Using local compression on disk takes 2 hours per DB backups. That is why I was trying to compress to tape using piping.

I'll check the if=- and bs= options.

As for the "/dev/rmt0.1", its probably it. I have seen this in other backups types we do.

The blocksize change command was just a summary of what I did before doing the DD. It is actualy a chdev.

Browser_ice

View Public Profile for Browser_ice

Find all posts by Browser_ice

10 More Discussions You Might Find Interesting

1. AIX

mt -f /dev/rmt0.1 status

Hello all, Anyboby knows what is the reason by which the ouput of the command mt -f /dev/rmt0.1 status on AIX does not show the same information that in the rest of platforms UNIX (Solaris, HP-UX, ...)? Then, what command of AIX is similar to mt- f /dev/rmt0.1 status of Solaris? We need it to...

2. Solaris

What is /dev/tty /dev/null and /dev/console

Hi, Anyone can help My solaris 8 system has the following /dev/null , /dev/tty and /dev/console All permission are lrwxrwxrwx Can this be change to a non-world write ?? any impact ??

3. AIX

Piping to /dev/rmt0 tape ?

I am trying to find a way to do the following on an AIX 4.2 with Korn: tar cvfpdl - . | compress > /dev/rmt0 The /dev/rmt0 is the device we use when we tar directly to it. I want to compress a folder's content to tape. Our current TAR does not have compression at all. We only have...

4. AIX

/dev/rmt0 pointed to from an NFS of another server ?

I only about the principle of filesystems from the very basics on Linux and Windows. But I want to know if it is possible on an AIX 4.2 to create one NFS on a server which is pointing to a tape drive (/dev/rmt0) of another server ? This is because we several backups to do on a 5 servers that...

5. UNIX for Dummies Questions & Answers

Script producing error, Program to calculate maximum number

Hi folks, Here i have written a shell script to calculate a maximum number from 10 numbers entered on command line. max=0 echo Enter 10 numbers , one at a time for i in 1 2 3 4 5 6 7 8 9 10 do read n max=`expr $max + $n` if --- At this last step there is some problem, it gives error...

6. AIX

rmt0 allows get increased .. !

rmt0 allows get increased .. ! I have faced this issue in my AIX server, rmt0 allows get increased and it's filled /root till 100% There is no tape in tape drive why it's increased? Pls advice..

7. Homework & Coursework Questions

iptables producing 'Unknown error 18446744073709551615' inRed Hat Enterprise Linux Server 5.5

Creating a large number of rules such as 100000, iptables will produce errors after 42000 rules "iptables: Unknown error 18446744073709551615". But another machine where i have debian virtual machine I can easily run the sciprt of 100000 of rules I am waiting for your reply 4....

8. AIX

"Please mount volume 2 on /dev/rmt0.1" message during mksysb restore

Dear all First of all, my English not so good. We have p52a (production server) and p52a (test server). Tape drives are VXA2. When both servers were AIX 5.3, mksysb on production server and restoring to test server was OK. The production server was AIX 5.3 and recently upgraded to...

9. Shell Programming and Scripting

Automating partitioning setup of /dev/sda on /dev/sdc

Objective: To recreate the partitioning setup of /dev/sda on /dev/sdc How would I parse the below information and initialize variables (an array?) that can be used to build sgdisk commands in a script, regardless of the number of partitions? Something along the lines of: sgdisk -n...

10. AIX

AIX native SNMP producing limited results when walking MIB tree

The company I work for has various AIX servers that I've recently migrated to AIX 7.1 (from 6.1). Some are powerHA clusters some are not. Likewise, the systems engineer that I replaced had net-snmp installed on said clustered systems. Long story short I am re-invoking AIX's native SNMP (v3) for...

LEARN ABOUT SUNOS

mt

mt(1)								   User Commands							     mt(1)

NAME

       mt - magnetic tape control

SYNOPSIS

       mt [-f tapename] command... [count]

DESCRIPTION

       The  mt	utility  sends	commands to a magnetic tape drive. If -f tapename is not specified, the environment variable TAPE is used. If TAPE
       does not exist, mt uses the device /dev/rmt/0n.

OPTIONS

       The following option is supported:

       -f tapename     Specifies the raw tape device.

OPERANDS

       The following operands are supported:

       count	       The number of times that the requested operation is to be performed. By default, mt performs  command once. Multiple opera-
		       tions of  command may be performed by specifying count.

       command	       Available  commands that can be sent to a magnetic tape drive. Only as many characters as are required to uniquely identify
		       a command need be specified.

		       eof	       Writes count EOF marks at the current position on the tape.
		       weof

		       fsf	       Forward spaces over count EOF marks. The tape is positioned on the first block of the file.

		       fsr	       Forward spaces count records.

		       bsf	       Back spaces over count EOF marks. The tape is positioned on the beginning-of-tape side of the  EOF mark.

		       bsr	       Back spaces count records.

		       nbsf	       Back spaces count files. The tape is positioned on the first block of  the  file.  This	is  equivalent	to
				       count+1 bsf's followed by one fsf.

		       asf	       Specifies absolute space to count file number. This is equivalent to a rewind followed by a fsf count.

		       If count is specified with any of the following commands, the count is ignored and the command is performed only once.

		       eom	       Spaces to the end of recorded media on the tape. This is useful for appending files onto previously written
				       tapes.

		       rewind	       Rewinds the tape.

		       offline	       Rewinds the tape and, if appropriate, takes the drive unit  off-line by unloading the tape.
		       rewoffl

		       status	       Prints status information about the tape unit.

		       retension       Rewinds the cartridge tape completely, then winds it forward to the end of the reel and back to	beginning-
				       of-tape to smooth out tape tension.

		       reserve	       Allows  the  tape  drive  to  remain  reserved  after closing the device. The drive must then be explicitly
				       released.

		       release	       Re-establishes the default behavior of releasing at close.

		       forcereserve    Breaks the reservation of the tape drive held by another host and then reserves the tape drive.	This  com-
				       mand can be executed only with super-user privileges.

		       erase	       Erases  the entire tape. Caution: Some tape drives have option settings where only portions of the tape may
				       be erased. Be sure to select the correct setting to erase the whole tape. Erasing a tape may  take  a  long
				       time depending on the device and/or tape. Refer to the device specific manual for time details.

		       config	       Reads  the  drives  current configuration from the driver and displays it in st.conf format. See st(7D) for
				       definition of fields and there meanings.

EXIT STATUS

       0	All operations were successful.

       1	Command was unrecognized or mt was unable to open the specified tape drive.

       2	An operation failed.

FILES

       /dev/rmt/*      magnetic tape interface

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Availability		     |SUNWcsu			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       tar(1), tcopy(1), ar.h(3HEAD), environ(4), attributes(5), mtio( 7I), st(7D)

BUGS

       Not all devices support all options. Some options are hardware-dependent. Refer to the corresponding device manual page.

       mt is architecture sensitive. Heterogeneous operation (that is, SPARC to x86 or the reverse) is not supported.

SunOS 5.10							    1 Sep 2004								     mt(1)