Generic restore from LTO tapes

[Tim Jones]

Hi Neil,

That’s what the TOLIS Tape Tools parts which are included with your BRU PE license are for – the “taperead” tool specifically in this case. It will allow you to read raw data from any tape and output that data to a disk file (or pipe it into another tool like tar or cpio). The downside is that you do need to have a basic understanding of how the tape was originally written including the block size that was used when writing the tape since there is no mechanism to ask a tape how it was written – variable vs. fixed block, 512b, 1024b, or another block size, etc. – to be able to properly read the content. You then need to understand how the originating software containerized the data when writing it to the tape (e.g.: tar, cpio, pax, bru, mtf, etc.) so that you can do something with the raw information once it is read from the tape.

For instance, to read a tape created with a Cache-A unit in tar format, we know two things – the tape was written in ustar format and it was written with a -b 300 blocking factor (tar uses 512-byte blocks, so that’s 150KB). To read a segment from that tape, you would use a command like this:

taperead -b 150k -f ntape0 | tar -tvvf – -b 300

That reads the raw data on the tape and sends it out via taperead’s “stdout” channel and then pipes it into tar’s “stdin” channel and would show you a table of contents (file listing) for the current segment on the tape.

For other formats, you would use a similar syntax, adjusting the -b argument as required, and sending the output to a disk file using redirection (“>”) or to an app like tar using a pipe (“|”).

Tim
—
Tim Jones
CTO – TOLIS Group, Inc.
https://www.tolisgroup.com
BRU … because it’s the RESTORE that matters!

[Neil Sadwelkar]

Tim,

Thanks. I am finding out first which host application wrote these tapes. It would vary between Quantel eQ/iQ systems, Autodesk Smoke/Flame systems. I’ve written to support at these companies to find out the info you mentioned – block size, container, format any other info they may have. Then, of course, testing.

Many companies have a large collection of LTO-2, LTO-3, LTO-4 tape with these mixed contents. I am urging them to discover what’s in them and to migrate the tapes to LTO-7 for future archive. This would also save them space with one LTO-7 taking care of 20-25 LTO-2 tapes, or 12-15 LTO-3 tapes.

Of course, the oldest LTO drive I have is an LTO-5, so if the quantity of LTO-2 is large, I’ll need to go buy an LTO-4 or LTO-3 drive.

———————————–
Neil Sadwelkar
neilsadwelkar.blogspot.com
twitter: fcpguru
FCP Editor, Edit systems consultant
Mumbai India

[Tim Jones]

The good news is that Autodesk uses tar for those system tapes. The big question there is simply the block size value.

One point of note – if you run into Quantum LTO-A tapes (the pre-cursor to Cache-A), those are a custom format and unless someone from Quantum’s old Seagate team can shed light on the container format, those are gone forever unless you can locate an LTO-3A or LTO-4A drive in the wild.

Tim
—
Tim Jones
CTO – TOLIS Group, Inc.
https://www.tolisgroup.com
BRU … because it’s the RESTORE that matters!