Re: Ontape restore to another server

Hey Marco! > >Ian Michael Gumby wrote: > > > > > > > >> Ian Michael Gumby wrote: > >> <SNIP> > >>> Remember its not just "integers" but all words would be flipped. > >>> > >> <SNIP> > >> > >> Careful. No ALL WORDS will be flipped. Intel, unlike some old > >> little-endian chips (DEC K10/K20 chips most notably) does not flip the > >> contents of words within a character array. Also, since DECIMAL and >it's > >> derived types in IDS (DATETIME, INTERVAL, etc.) are not native types >they > >> are also not byte flipped. So before you willy-nilly flip every word >of > >> data on the tape you have to process the table schema's for each table. [SNIP] > >Actually, the flipping part is not so trivial - aside from shorts and ints, >which are easy enough, there's the floating point representation for >instance, >which changes from architecture to architecture - which in turn requires >knowledge of the schema of the tables, and row uncompressing to identify >where >the floats are, and then row compressing - a triple whammy which would >make >the conversion orders of magnitude slower (for other types this is not >necessary, but I won't go into the technical details). > >And then there's port page size, and platform specific stuff like differing >path formats between NT and *xes. >And this doesn't even begin to take into account disk differences in >between >versions (surely you would want to do to be able to do something like >restore >with a 10 an archive produced by a 9) > >Doable, but not easy, and not entirely sure it's worth the risk. >Look at archiving and migration as specialized race cars. Sure, you can >have a >rally car go almost everywhere and run decently on track, but it will be no >match to an F1 in its own environment. > >-- >Ciao, >Marco Hey Marco! I think a lot of people are missing the point. Integer and FP conversions are *trivial* knowing where they are in the page is not. And of course the $64,000 question: What meta data is stored on the ontape archive? Do we know the data layout within the page? If not, then you're screwed. This is why I said you'll need an NDA with IBM. But I do agree with you that finding enough use cases to justify the cost of development would be difficult. From an IBM perspective, you *could* justify this type of tool as something that would improve/enhance future generations of back up systems. (Call it pure R&D). _________________________________________________________________ >From photos to predictions, The MSN Entertainment Guide to Golden Globes has it all. http://tv.msn.com/tv/globes2007/