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. <div>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. </div>
<div>Is that correct? Or is there another mechanism. Or do I need to look into the code if it can not be easily explained?</div><div><br></div><div>Thanks</div><div>Jiawei</div><div><br><div class="gmail_quote">On Mon, Feb 7, 2011 at 3:23 PM, Pandelis Theodosiou <span dir="ltr"><<a href="mailto:ypercube@gmail.com">ypercube@gmail.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;"><br><br><div class="gmail_quote"><div><div></div><div class="h5">On Tue, Feb 8, 2011 at 12:17 AM, Jiawei Jiang <span dir="ltr"><<a href="mailto:jiawei@email.arizona.edu" target="_blank">jiawei@email.arizona.edu</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0pt 0pt 0pt 0.8ex;border-left:1px solid rgb(204, 204, 204);padding-left:1ex">
Hi<div><br></div><div>I am studying your system. First, it is a very nice system.</div><div>I have confusion on the storage availability:</div><div><span style="font-family:Calibri,sans-serif;font-size:14px">"Users
do rely on storage servers for <i>availability</i>. The cipher text is
erasure-coded and distributed across <i>N</i> storage servers (the default value
for <i>N</i> is 10) so that it can be recovered from any <i>K</i> of these
servers (the default value of <i>K</i> is 3). Therefore only the simultaneous
failure of <i>N-K+1</i> (with the defaults, 8) servers can make the data
unavailable."</span></div><div><span style="font-family:Calibri,sans-serif;font-size:14px">I do not know how it works, how a file is encrypted and distributed among these server. </span><span style="font-family:Calibri,sans-serif;font-size:14px">Could anyone briefly explain it to me?</span></div>
</blockquote></div></div><div><br>File is encrypted, then cut in small pieces and the pieces get distributed to the N servers.<br>If any K servers are available, the file can be recontructed from the pieces.<br>If less than K servers are available, it can't.<br>
<br>Not a 100% accuarte explanation but brief (and hopefully clear).<br><font color="#888888"><br>Pandelis<br><br> </font></div><div class="im"><blockquote class="gmail_quote" style="margin:0pt 0pt 0pt 0.8ex;border-left:1px solid rgb(204, 204, 204);padding-left:1ex">
<div><span style="font-family:Calibri,sans-serif;font-size:14px">Thanks very much.</span></div><div><span style="font-family:Calibri,sans-serif;font-size:14px"><br>
</span></div><div><span style="font-family:Calibri,sans-serif;font-size:14px">Jiawei Jiang</span></div>
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