topic Re: tar & dd problem in Operating System - HP-UX

tar & dd problem

xertusit — Thu, 09 Feb 2006 07:40:34 GMT

Hi fellas,
i've backupped io2 file via tar. Now I want extract io2 not via tar but via dd. The operating system returned me these error:
# tar tv
-rw-r--r-- 0/1 36567531 Feb 9 12:18 2006 io2
drwx------ 0/0 0 Feb 6 15:50 2006 lost+found/
# dd if=/dev/rmt/0 of=/dev/null
read: Not enough space
0+0 records in
0+0 records out

Of course the file system where I restore the io2 file have the right space available.

Thanxs,
Massimo

Re: tar & dd problem

Robert-Jan Goossens_1 — Thu, 09 Feb 2006 07:59:31 GMT

Massimo,

where is the file io2 ?

is this a typo?

# dd if=/dev/rmt/0 of=/dev/null
# ll /dev/rmt/0

Robert-Jan

Re: tar & dd problem

Devender Khatana — Thu, 09 Feb 2006 08:04:30 GMT

Hi,

The file backup up using tar can not be extracted using dd. dd does block by block copy and it below file level.

Use tar itself to extract the file

#tar -xvf io2 .

HTH,
Devender

Re: tar & dd problem

xertusit — Thu, 09 Feb 2006 08:07:06 GMT

The file /dev/rmt/0 is a link to /dev/rmt/0m

Re: tar & dd problem

Luk Vandenbussche — Thu, 09 Feb 2006 08:07:19 GMT

Hi,

If your file is on a tape you must use /dev/rmt/0m

Re: tar & dd problem

xertusit — Thu, 09 Feb 2006 08:12:51 GMT

The /dev/rmt/0 is a link to /dev/rmt/0m.

Re: tar & dd problem

paolo barila — Thu, 09 Feb 2006 08:13:23 GMT

# mt rew

# tar xvf /dev/rmt/0mn io2

Re: tar & dd problem

xertusit — Thu, 09 Feb 2006 08:18:09 GMT

I don't interested if the data into dds data are archived via tar or frecover...I need to understand the way to dump a dds dat into a temporary file system via dd.

Massimo

Re: tar & dd problem

Zinky — Thu, 09 Feb 2006 09:36:50 GMT

Brion - Peace:

Try this:

mt -f /dev/rmt/0mn rew

Then, the following will extract the first "file" (be it tar, fbackup, dump, vxdump format) on the tape:

dd if=/dev/rmt/0mn of=/somefs/tapefile.1 bs=10240

Then test the recovered "raw" file with:

tar tvf /somefs/tapefile.1

Note: if the "tar file" on the tape was backed up with no blocking factor -- its default will be 20 (@ 512bytes). That is why you need to specificy it in your dd command.

If you've multiple "files", then just continue usingwith yur dd'd noting the bllock size of your "files". You may also use the "mt asf/fsf" file positioning commands if you want to go to a particular "file" on your tape.

Hope this helps.

Re: tar & dd problem

xertusit — Thu, 09 Feb 2006 10:25:06 GMT

There was a bs wrong...I've tried with 128k and now it's all ok!!

Massimo