On Tue, Jun 13, 2006 at 09:35:31AM -0400, Joshua Baker-LePain wrote:
> On Tue, 13 Jun 2006 at 3:05pm, Paul Bijnens wrote
> 
> >On 2006-06-13 12:55, Toralf Lund wrote:
> 
> >It could also help the current minor problem that taping starts only
> >when the DLE is completely dumped to holdingdisk.
> >The current implementation also assumes the tape chunks follow
> >sequentially on the tape.  This is not strictly necessary either.
> >
> >Allowing tape-chunks to be interspersed with chunks from other DLE's
> >together with multi-run taping... Wow, that would make Amanda really
> >one of the best free backup programs!
> 
> Again, let the curmudgeon step in here.  One of the initial design 
> principles of amanda was the ability to get your data off the tapes with 
> *no* amanda tools -- mt, dd, and tar or restore were all that was needed. 
> Tape spanning as implemented has already broken that, requiring 
> amfetchdump to reassemble spanned DLEs...
> 
> I think.  I honestly don't know how badly the principle has been broken. 
> Can one simply cat the 2 (or more) spanned images together (minus some 
> header info perhaps) and get the whole image back?
> 
> But I do know that interspersing tape chunks from multiple DLEs would 
> absolutely destroy any hopes of getting your data off the tapes without 
> amanda's tools *and* record keeping.  With live CDs so prevelant these 
> days, keeping copies of the amanda tools around is dead easy.  But, 
> IMNSHO, losing the ability to get your data off the tapes if you lose your 
> amanda database is unacceptable.
> 

My feelings exactly JLB.

Tape spanning was an important addition.  I was willing to accept
the loss of easy recovery without amanda because of its importance
and because it is optional on a DLE by DLE basis.

Plus I feel, without confirming this, that you could fairly easily
combine the tape splits (should we call them splits vs holding disk
chunks?) using standard tools.

But I would certainly hesitate to go much further and further
complicate standard tool recovery.  That ability saved me twice already.

-- 
Jon H. LaBadie                  jon AT jgcomp DOT com
 JG Computing
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