Jon LaBadie <jon AT jgcomp DOT com> writes:

> On Mon, Dec 08, 2008 at 01:15:21PM +0100, Sven Rudolph wrote:
>> Nick Brockner <nbrockne AT hamilton DOT edu> writes:
>> 
>> > I have an interesting problem.  I have old archive tapes on DAT72
>> > tapes which I need to move over to my new LTO3 tapes.  The dat72
>> > changer is on a different server than the new lto3 changer.
>> >
>> > What is the best way to migrate the data?
>> 
>> Probably not the best way, but I'll try to describe what I do:
>> 
>> I copy the old tapes to disk, each in a separate directory named 1, 2
>> and so on. Each "tape file" (the things separated by "file marks") is
>> copied into on disk file, they are numbered too. Example:
>> 
>>   mkdir 1
>>   cd 1
>> 
>>   n=0
>> 
>>   while dd if=$TAPE bs=32k of="$(printf '%03d' $n)"
>>   do
>>         n=$((n+1))
>>   done
>> 
>> When I copied enough tapes that will fit on a new tape, I do some
>> checking, and after that I write the files to a new tape:
>> 
>>   for f in */*
>>   do
>>         dd if=$f of=$TAPE bs=32k conv=sync
>>   done
>> 
>> Afterwards some more checking...
>> 
>> The resulting tape can be used with amrecover, but you can not use the
>> "amrecover_do_fsf" and "amrecover_check_label" options, because the
>> amanda database does not know the file positions of the new tape. Its
>> OK for me, restores from these old tapes are very rare.
>> 
>> I started using this with DLT-IV (35 GB), and now I use LTO-4 (800
>> GB), so one new tape replaces more than ten old tapes.
>> 
>
> Interesting Sven,  I'm trying to wrap my mind around how a
> typical amrecover session would work.  Suppose I've used
> amrecover to mark several files/directories for recovery.
> Amrecover then uses its index and suppose it says that
> tape "old-7" is needed.  I consult my migration TOC and
> see that tape "old-7" is one of the tapes migrated to
> tape "new-2".  So I put tape "new-2" in the drive.
>
> What happens next?
> Or are my assumptions of the steps to this point faulty?

An old tape contains these files
1  Amanda Header (for TAPE001)
2  First Data File
3  Second Data File

and the second old tape contains:
1  Amanda Header (for TAPE002)
2  Third Data File

Now these are concatenated onto a new tape:
1  Amanda Header (for TAPE001)
2  First Data File
3  Second Data File
4  Amanda Header (for TAPE002)
5  Third Data File

When I want to recover the Third Data, I insert the tape, position it
with mtx and let amrecover read it.

There is nothing like a "new-2" name, at least not known to
Amanda. Amanda does not know that these tapes reside on a new larger
tape. (Thats the reason why Amanda cannot check the tape header: It
rewinds, finds the TAPE001 header and decides that it is the wrong
tape.)

The list mapping the Data File names to the positions is kept outside
of Amanda. (I keep it as a both as a file and as paper inside the
physical tape box.)

        Sven