When a user wants to download the file, how to make sure that pieces from any 3 (or K) servers can be assembled into the original file. This is what I guess: if N=10, K=3, the file will be divided into 3 pieces(note as piece 1, 2, 3), each server will has 3 pieces (piece 1,2,3) stored. But when reconstructing, the 3 pieces must come from different server. Pieces from same server can not be assembled due to some encryption methods. So as long as any K servers are working, the user can get file. And we will need 10MB totally to store a 1MB file. Is that correct? Or is there another mechanism. Or do I need to look into the code if it can not be easily explained?
Thanks Jiawei On Mon, Feb 7, 2011 at 3:23 PM, Pandelis Theodosiou <[email protected]>wrote: > > > On Tue, Feb 8, 2011 at 12:17 AM, Jiawei Jiang <[email protected]>wrote: > >> Hi >> >> I am studying your system. First, it is a very nice system. >> I have confusion on the storage availability: >> "Users do rely on storage servers for *availability*. The cipher text is >> erasure-coded and distributed across *N* storage servers (the default >> value for *N* is 10) so that it can be recovered from any *K* of these >> servers (the default value of *K* is 3). Therefore only the simultaneous >> failure of *N-K+1* (with the defaults, 8) servers can make the data >> unavailable." >> I do not know how it works, how a file is encrypted and distributed among >> these server. Could anyone briefly explain it to me? >> > > File is encrypted, then cut in small pieces and the pieces get distributed > to the N servers. > If any K servers are available, the file can be recontructed from the > pieces. > If less than K servers are available, it can't. > > Not a 100% accuarte explanation but brief (and hopefully clear). > > Pandelis > > > >> Thanks very much. >> >> Jiawei Jiang >> >> > <http://int.ask.com/web?siteid=10000861&webqsrc=999&l=dis&q=in%20> > _______________________________________________ > tahoe-dev mailing list > [email protected] > http://tahoe-lafs.org/cgi-bin/mailman/listinfo/tahoe-dev > >
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