Visit The New, Modern Unix Linux Community


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


 
Thread Tools Search this Thread
Operating Systems AIX aix 4.2 : using dd of=/dev/rmt0 producing error
# 1  
aix 4.2 : using dd of=/dev/rmt0 producing error

I want to compress backup files to tape using compress on our AIX 4.2

- Our TAR does not have compression.
- I do not want to use local storage to compress as most of the filesystems are pretty full.
- the only compressing tool we have is 'compress'
- tapes are 5Gb 8mm


I am trying this :

change tape block_size=512 (default dd obs value)
tar -cvpdlBf - a_folder | compress | dd of=/dev/rmt0

but it is giving me :
dd: 0511--53 The write failed.
: A system call received a parameter that is not valid.


but using something like this works:
tar -cvpdlBf - a_folder | compress | dd of=/tmp/zzz.Z
# 2  
Any idea on what is the problem ?
# 3  
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 to use "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

Last edited by bakunin; 07-07-2009 at 09:41 PM.. Reason: edited typos
# 4  
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.
# 5  
sometimes the backup problem may be coz of the device driver. If proper device driver is not installed then it might cause the problem I have faced it many times.
please check Driver and firmware that might help.
# 6  
Quote:
Originally Posted by pchangba1
sometimes the backup problem may be coz of the device driver. If proper device driver is not installed then it might cause the problem I have faced it many times.
please check Driver and firmware that might help.
I have no ideas on how to do that. I am only a very basic operator. Our system admin is not a real system admin (lack of knowledge and lack of practic).

This client's system is old and over 20 years old (AIX 4.2).
# 7  
can u post the output of the following command
#oslevel -a

can u also send the detail of the tape i.e. machine type and serial number

Previous Thread | Next Thread
Thread Tools Search this Thread
Search this Thread:
Advanced Search

Test Your Knowledge in Computers #33
Difficulty: Easy
In HTTPS, the letter 'S' stands for 'safe'.
True or False?

10 More Discussions You Might Find Interesting

1. 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... (1 Reply)
Discussion started by: davix
1 Replies

2. 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... (12 Replies)
Discussion started by: RogerBaran
12 Replies

3. 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... (3 Replies)
Discussion started by: fifa15pc
3 Replies

4. 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.... (1 Reply)
Discussion started by: tahirfattani
1 Replies

5. 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.. (1 Reply)
Discussion started by: Mr.AIX
1 Replies

6. 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... (5 Replies)
Discussion started by: rits
5 Replies

7. 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 Replies)
Discussion started by: Browser_ice
5 Replies

8. 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... (5 Replies)
Discussion started by: Browser_ice
5 Replies

9. 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 ?? (12 Replies)
Discussion started by: civic2005
12 Replies

10. 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... (0 Replies)
Discussion started by: smoraprosol
0 Replies

Featured Tech Videos