On Tue, Dec 09, 2008 at 06:19:32PM +0100, Sven Rudolph wrote:
> 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.)
>
I think my big problem was thinking that amrecover would
rewind the tape before checking the label.
We gotta find a way to redo the indexes and other files
that are needed for recovery and continued dumping.
jl
--
Jon H. LaBadie jon AT jgcomp DOT com
JG Computing
12027 Creekbend Drive (703) 787-0884
Reston, VA 20194 (703) 787-0922 (fax)
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