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A software or tool to recover formated lto Tapes  

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Ma.algendy
(@ma-algendy)
New Member

Hello 

I'm looking for an advice regarding a software that can read a Formatted LTO 5 Tape and read the data stored on it.

 

the software used was ARchiware P5 . it usually replace the tape name portion and doesn't clear all data stored on the tape when we relabel the tape and that give us a chance to read the untouched sectors.

 

i tried to use dd tool . however, it gives me a message saying that a file marker has been reached and stops after a couple of second .

 

 can anyone give my an advice on how i can manage solving this problem or even a software that can be used ?

 

Best Regards

Mahmoud

 

 

Quote
Topic starter Posted : 05/11/2020 12:24 pm
mscotgrove
(@mscotgrove)
Senior Member

As far as I am aware there is no software solution to your problem. When anything is written to an LTO tape all previous data is blocked.  Thus if a tape is relabelled, eg a few 80 byte header blocks, all previous data is lost.

 

If a tape is filled to 10% capacity, the previous 90% is lost.  This has been true for most tape drives over the past 40 years - only open reel tape could be processed after end of media mark.

 

A drive will report End of Media after these three blocks and nothing can be done.

 

The only hope would be firmware changes to the drive, but no standard/specialised software tool will help you.

 

I did know one person/company who could work with overwritten DLTs.  He had two subcontractors to do half the work each.  They did not know each other.  Despite buying him dinner a few times, I never got a useful clue to how he did it.  Unfortunately he died a few years ago.

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Posted : 05/11/2020 1:01 pm
mscotgrove
(@mscotgrove)
Senior Member

I've just looked up details of the software you are using, and it looks as if it is based on LTFS.  Everything I wrote in my previous post is correct (I hope) but LTFS has a slightly different dimension.

 

LTFS partition the tape into an index and a data stream.  By rewriting the short index partition it can appear to make files in the main stream disappear.  This is the same as using UDF on CD-R disks.  The data may still exist, but the index for has been replaced.

With your DD command, you want to make sure you are reading the correct partition.  If both are very short, then your data is lost.  You implied it reached FM/EOM very quickly.  Check the second partition.  If you find a long partition, then recovery will be possible.

If both partitions are short, or only one partition, then sorry.

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Posted : 05/11/2020 1:15 pm
jaclaz
(@jaclaz)
Community Legend

Why do I have a deja vu feeling?

https://www.forensicfocus.com/forums/general/lto-tapes-read-errors/

jaclaz

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Posted : 05/11/2020 2:35 pm
Ma.algendy
(@ma-algendy)
New Member

@Michael 

I'm really new with the dd command and I'm trying to find some clear document on how I can find a way to read each partition separately . but i think this will need to know how the developer deal with the tape .such as , the size of the naming and index partition . i will contact the support to get this data , hoping they can share some .

 

my questions is : 

i have contacted a recovery service company regarding this tape before and after i sent them some information about the software , they said that it is possible to get back the data. if there is no software can be used in my situation . how  does all these recovery companies work ? what are the tools they used to their magic ? I'm not specialized but of course I have a a great curiosity .

 

Best Regards

Mahmoud Al.Gendy

 

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Topic starter Posted : 05/11/2020 5:05 pm
jaclaz
(@jaclaz)
Community Legend
Posted by: @ma-algendy

 

my questions is : 

i have contacted a recovery service company regarding this tape before and after i sent them some information about the software , they said that it is possible to get back the data. if there is no software can be used in my situation . how  does all these recovery companies work ? what are the tools they used to their magic ? I'm not specialized but of course I have a a great curiosity .

 

In cases like this it *seems* like they do two things:

1) *somehow* modify the tape drive firmware to "ignore" or "bypass" the EOD
2) read the data as RAW and then (attempt to) re-build the partition

The first (even if it is strictly speaking software) is actually hardware (as likely will work only on a specific make/model of the drive and flashing/modifying the firmware may need some specific tools).

The second is software + (I believe) some experienced/skilled operator.

See also:

https://www.forensicfocus.com/forums/general/recover-deleted-data-from-backup-tapes/

jaclaz

 

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Posted : 05/11/2020 5:49 pm
mscotgrove
(@mscotgrove)
Senior Member

@jaclaz

Your point 1 is changing the firmware and I think this is the only option. Paul Sanderson rather comfirmed this in the link you gave.

On point 2, I have spent nearly 20 years reading LTO tapes (since LTO-1) and I am not aware of a raw read option. I presume you mean reading a frame from the tape, maybe before error correction etc. 

Can you indicate which (SCSI) command you would use. I would be interested to try it.  The only reference to raw read I can find, is related to encryption

 

@ma-algendy

Does your company claim to have hardware to read a 'truncated' tape, or just reconstruct an LTFS tape (the second is fairly simple)

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Posted : 05/11/2020 6:12 pm
jaclaz
(@jaclaz)
Community Legend

Very likely they have also a modded driver that allows to read in "not conventional" ways, from what I understand (set aside the EOD issue) there are specific tools. *like*:

https://creativecow.net/forums/thread/generic-restore-from-lto-tapes-2/

Actual manual of the thingy:

https://www.tolisgroup.com/assets/tolis_tape_tools_manual_01-10-08.pdf

but most probably the - I believe very few - specialized firms have their own internal software tools, and most probably they leverage on the modified firmware.

Ltfs may have additional possibilities (or roadblocks), there is a ltfschk that seems like a sort of chkdsk for tapes:

https://github.com/amiaopensource/ltfs

but no idea if it may do anything useful.

jaclaz

 

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Posted : 05/11/2020 7:09 pm
Ma.algendy
(@ma-algendy)
New Member

It looks too hard for me following either one of the two ways. 

Eod is blocking me from reading the old media and I don't know how to modify the Tandberg firmware to stop the Eod check. It looks much easier in case of the tape was ltfs. As there is a way to mount the tape with noeod check.

I'm using the Mt tool to load the tape but I can not find any command to skip the Eod check. 

 

Reading the tape as raw, seems to be hard too as Thanks to the links you sent me jaclaz. I need to know more information on how the tape is written and the start of the data portion.

@mscotgrove

I do not have any information on how they are doing it. But they are a very well known recovery service company. 

 

Many Thanks for your help. 

Hope we can find an easier solution for this issue soon. 

 

 

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Topic starter Posted : 05/11/2020 11:14 pm
mscotgrove
(@mscotgrove)
Senior Member
Posted by: @jaclaz

Very likely they have also a modded driver that allows to read in "not conventional" ways, from what I understand (set aside the EOD issue) there are specific tools. *like*:

 

This issue with this post is EOD.

The links you posted show standard 'SCSI' commands to a tape drive.

A modified Windows/Unix driver will not allow for reading in not conventional ways.  There are not many commands with a tape drive.  Basic ones are Read (fixed or variable block size), Space (locate) Rewind.

Any guidance where I can find the 'Raw read' command, as opposed to just reading tape blocks.

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Posted : 06/11/2020 10:36 am
jaclaz
(@jaclaz)
Community Legend
Posted by: @mscotgrove

This issue with this post is EOD.

The links you posted show standard 'SCSI' commands to a tape drive.

A modified Windows/Unix driver will not allow for reading in not conventional ways.  There are not many commands with a tape drive.  Basic ones are Read (fixed or variable block size), Space (locate) Rewind.

Any guidance where I can find the 'Raw read' command, as opposed to just reading tape blocks.

I know, this is EXACTLY why I specified "(set aside the EOD issue)"

From the Tolis manual I linked to.

Reading a tape with taperead
The taperead utility reads the raw data from a tape and provides it as
standard output to be used by whatever utility that you wish to pipe it to. 

you can sue the good Tolis guys if you believe they misrepresented what that tool does.

 

A driver (at least under Windows) can do "queer" things, though, as said I believe that *something* else is used by the specialized tape recovery companies, a common example (again unrelated to this thread and provided ONLY as a comparison) is the special driver coming together with some "Manufacturer Tool" for USB sticks, that provide access to areas of the stick or of its controller that are otherwise unreachable.

jaclaz

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Posted : 06/11/2020 5:20 pm
mscotgrove
(@mscotgrove)
Senior Member

 

Reading a tape with taperead
The taperead utility reads the raw data from a tape and provides it as
standard output to be used by whatever utility that you wish to pipe it to. 

 

I am fairly certain that in this context, 'raw data' is just block by block data off the tape.  This is a simple SCSI command.

It does nothing to help with the question of reading past EOD.

 

I have no intention of suing anyone.  I just want to try and help with the original question in a field I have worked on for over 35 years, which has involved many 100s of hours pouring over SCSI reference manuals for all types of tape drive, starting with Open Reel Tape (9 track), and with SCSI, SAS, Fibre, USB, Pertec interfaces for DOS, Windows and Unix.

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Posted : 06/11/2020 5:49 pm
jaclaz
(@jaclaz)
Community Legend
Posted by: @mscotgrove

It does nothing to help with the question of reading past EOD.

And AGAIN I know, and explicitly said so, TWICE.

The EOD can be bypassed AFAIK ONLY by a tape drive with modified firmware, or - but I strongly doubt it can apply to LTO/LTFS tapes -  maybe with this or similar approach:

http://pages.cs.wisc.edu/~plonka/sysadmin/backup.html

which is clearly a high risk one and which I explicitly DO NOT recommend.

jaclaz

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Posted : 06/11/2020 7:26 pm
mscotgrove
(@mscotgrove)
Senior Member

So basically you/we do not have a solution for the original question.

 

I hope his recovery company can assist

ReplyQuote
Posted : 06/11/2020 7:35 pm
jaclaz
(@jaclaz)
Community Legend
Posted by: @mscotgrove

So basically you/we do not have a solution for the original question.

 

I hope his recovery company can assist

Sure we have it not for the original question, if you check I was replying to the later questions, the ones that go like:

my questions is : 

i have contacted a recovery service company regarding this tape before and after i sent them some information about the software , they said that it is possible to get back the data. if there is no software can be used in my situation . how  does all these recovery companies work ? what are the tools they used to their magic ? I'm not specialized but of course I have a a great curiosity .

which I had explicitly quoted.

Questions in this thread by the OP:

1) can anyone give my an advice on how i can manage solving this problem or even a software that can be used ?

2) if there is no software can be used in my situation . how  does all these recovery companies work ?

3) what are the tools they used to their magic ?

You replied to #1, I tried to answer #2 and #3.

jaclaz

ReplyQuote
Posted : 06/11/2020 7:51 pm
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