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The content of this blog is my personal opinion only. Although I am an employee - currently of Nvidia, in the past of other companies such as Iagination Technologies, MIPS, Intellectual Ventures, Intel, AMD, Motorola, and Gould - I reveal this only so that the reader may account for any possible bias I may have towards my employer's products. The statements I make here in no way represent my employer's position, nor am I authorized to speak on behalf of my employer. In fact, this posting may not even represent my personal opinion, since occasionally I play devil's advocate.

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Friday, November 06, 2015

Stupid Blogger does not understand difference between symbolic link and data deduplication

See the quote from a UNIX bigot's blog at bottom.



Now, I am a UNIX bigot.  But I also try to be an unbiased UNIX bigot.



In particular, I understand the difference between data deduplication - a filesystem where two completely separate files that happen to have the same contents will be transparently linked, behind the user's back, to share physical storage.



Linked in such a way that, if one file is modified and the other is not, then the change is NOT propagated to the other.



I.e. linked transparently to the user.  Invisibly, except for occupying less disk space.



Symlinks are sometimes used as a "poor man's" approximation to this.  But symlinks are definitely not transparent.  E.g. if the target file is removed, the symlink dangles.  That should not happen in a proper "single instance store".



For this matter, UNIX hardlinks can be used as a "poor man's" approximation to this.   But, again, not transparent.



Now, I do not know if Microsoft's single instance store is fully transparent.  But I suspect it is - or at least more so than symlinks or hardlinks.



The Civilized Explorer Travel Bizarre Link Page: "Microsoft Innovations. This is an actual press release dated February 28, 2000, on the actual Microsoft Web site wherein Bill Bolosky and two Microsoft colleagues claim to have invented symbolic links three years ago!
... an idea occurred to them -- why not save operating system disk space by storing duplicate files as links that point to a single file housed in a central location?
Are these guys brilliant ...
During the next 1-1/2 years, Bolosky, a researcher in Microsoft Research's Systems and Networking Group, and three of his researchers worked full time with the Windows 2000 team to build the technology, now known as the Single Instance Store.
Or what?
And you thought Microsoft's only innovations came from other companies that they either bought or crushed."


Stupid UNIX bloggers unite!  You have nothing to reveal to the Internet except your ignorance, and inability to absorb new concepts!



'via Blog this'

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