LinuxQuestions.org
Welcome to the most active Linux Forum on the web.
Go Back   LinuxQuestions.org > Forums > Linux Forums > Linux - Newbie
User Name
Password
Linux - Newbie This Linux forum is for members that are new to Linux.
Just starting out and have a question? If it is not in the man pages or the how-to's this is the place!

Notices



Reply
 
Search this Thread
Old 11-16-2012, 12:34 PM   #1
Preacherpj
LQ Newbie
 
Registered: Mar 2011
Posts: 19

Rep: Reputation: 0
LTO4 - tape data extraction problem


Hi everybody -

**Full disclosure, I'm a Linux beginner**

I work in an environment where we receive data in different formats, extract it and then manipulate it. Often the data comes on hard drives - but yesterday we recieved a chunk of information on an LTO-4 tape and I'm having a difficult time getting it off.

We have a CENTOS machine connected to a LTO-4 tape drive. I put the tape in and used

mt -f /dev/nst0 rewind (the drive activity light lit up and the tape rewound, so I know the connection is good and NST0 is the correct drive designation)

To get data off I tried
tar -xvf /dev/nst0 which results in:

tar: /dev/nst0: Cannot read: Cannot allocate memory
tar: At beginning of tape, quitting now
tar: Error is not recoverable: exiting now

I tried manipulating the block size - tried
mt -f /dev/nst0 setblk 0
mt -f /dev/nst0 setblk 512

but I get the same error either way.

Would really appreciate any help in figuring out how to get this data off the tape!

thanks in advance,
Ryan
 
Old 11-16-2012, 01:36 PM   #2
michaelk
Moderator
 
Registered: Aug 2002
Posts: 12,392

Rep: Reputation: 843Reputation: 843Reputation: 843Reputation: 843Reputation: 843Reputation: 843Reputation: 843
Just for clarification device /dev/st0 should rewind the tape after the current operation is completed and /dev/nst0 should not rewind the tape.

Do you know how the data was written to tape? Try the following:

tar -t --blocking-factor=128 -xvf /dev/st0
 
Old 11-16-2012, 02:12 PM   #3
Preacherpj
LQ Newbie
 
Registered: Mar 2011
Posts: 19

Original Poster
Rep: Reputation: 0
Michael -

Thanks for the help, I truly appreciate.

So I entered
tar -t --blocking-factor=128 xvf /dev/st0 and hit 'enter'

How long should that command take to process? I see the small blinking black square flashing underneath that command - but nothing else. I also don't hear the tape spinning. It's been doing this for about 20 mins now. Is this typical for this command?

Thanks again
 
Old 11-16-2012, 02:18 PM   #4
michaelk
Moderator
 
Registered: Aug 2002
Posts: 12,392

Rep: Reputation: 843Reputation: 843Reputation: 843Reputation: 843Reputation: 843Reputation: 843Reputation: 843
No it shouldn't. I would press Ctrl^c to cancel.

Do you know how the data was written to tape?
 
Old 11-16-2012, 02:25 PM   #5
Preacherpj
LQ Newbie
 
Registered: Mar 2011
Posts: 19

Original Poster
Rep: Reputation: 0
Quote:
Originally Posted by michaelk View Post
No it shouldn't. I would press Ctrl^c to cancel.

Do you know how the data was written to tape?
Unfortunately no, its off a system that is proprietary. We've gotten other tapes in the past DDS, AIT3 tapes that I've gotten data off of using this CENTOS deck, but this is my first crack at a LTO4 tape.

For various reasons it would be difficult to query the site to get more information on how the data was recorded.
 
Old 11-16-2012, 03:09 PM   #6
michaelk
Moderator
 
Registered: Aug 2002
Posts: 12,392

Rep: Reputation: 843Reputation: 843Reputation: 843Reputation: 843Reputation: 843Reputation: 843Reputation: 843
I would assume that the same basic process would work independent of the type of media. Is tar what you normally use?
 
Old 11-16-2012, 03:15 PM   #7
Preacherpj
LQ Newbie
 
Registered: Mar 2011
Posts: 19

Original Poster
Rep: Reputation: 0
Yup, I always use tar.

Depending on what type of media we get in, I have to mess around with the block size until I find the right match - but that doesn't seem to be working here. Is there a way to determine what block size I need to set on the media?
 
Old 11-16-2012, 04:04 PM   #8
michaelk
Moderator
 
Registered: Aug 2002
Posts: 12,392

Rep: Reputation: 843Reputation: 843Reputation: 843Reputation: 843Reputation: 843Reputation: 843Reputation: 843
Well I thought the block size for the LTOs was 64k but it could be 32K which would make the block size factor 64 instead of 128.

Just curious have you tried writing and reading to a blank tape to verify the drive is functioning correctly?
 
Old 11-19-2012, 09:18 AM   #9
Preacherpj
LQ Newbie
 
Registered: Mar 2011
Posts: 19

Original Poster
Rep: Reputation: 0
Mike -

I am able to read/write to LTO tapes using the drive - its practically brand new. I think its a block-size issue...........is there anyway that you know of to run some type of check to see what the block size might be? I thought there was a way to skip a block forward and then check to see how much data you skipped to see the block size?
 
Old 11-19-2012, 10:16 PM   #10
michaelk
Moderator
 
Registered: Aug 2002
Posts: 12,392

Rep: Reputation: 843Reputation: 843Reputation: 843Reputation: 843Reputation: 843Reputation: 843Reputation: 843
I've never tried this method so I do not know if it actually works.
http://www.cyberciti.biz/faq/rhel-ce...ape-blocksize/
 
  


Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is Off
HTML code is Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Enabling encryption on LTO4 tape drive ninthbit Linux - Server 2 10-22-2010 03:04 PM
Use Dell LTO4 SAS tape drive dippitydip Linux - Newbie 2 09-20-2008 11:25 AM
problem while restoring data from tape drive using mt shellarchive Red Hat 1 07-09-2008 11:54 AM
Data extraction from a really, really huge file. thekillerbean Linux - Software 4 04-09-2006 05:18 AM
pcap data extraction black_man Linux - Networking 1 08-28-2004 09:52 AM


All times are GMT -5. The time now is 09:05 PM.

Main Menu
Advertisement
My LQ
Write for LQ
LinuxQuestions.org is looking for people interested in writing Editorials, Articles, Reviews, and more. If you'd like to contribute content, let us know.
Main Menu
Syndicate
RSS1  Latest Threads
RSS1  LQ News
Twitter: @linuxquestions
identi.ca: @linuxquestions
Facebook: linuxquestions Google+: linuxquestions
Open Source Consulting | Domain Registration