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<p class="MsoNormal"><span style="font-size:11.0pt">It’s kind of a cluster, but not exactly HPC.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">What I have is 3 rPi computers, A,B, and C, and what I’d like to do is keep the desktop and some data directories on all of them synchronized. So if on node A, I add something to A:~/Desktop, it (in short
order) winds up in the ~/Desktop directory on the other 2 machines.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">It’s easy if I’m doing it from another computer – pdsh and similar do a great job turning a single command into 3 (or N).<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">But what if it’s on the node itself. I thought about something like rsync running every second or 10 seconds, or whatever.
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">But maybe there’s a clever-er way. The network connection isn’t perfect, so a “map it to a shared network drive” approach doesn’t work, and there’s no guarantee that the state is the same on all machines (i.e.
one might drop off and reset, and be way behind the other two). And, the changes might come from any source (i.e. I can’t run all file changes through some single entry point that does a pdsh like “write 3 times”)<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">Here's a sort of use case: the three nodes are in physically different locations, nominally connected by a network connection that is unreliable. You, user of the system, is at Node A, and in the course of
debugging a function, decide that you need to change some files, so you do that, locally. And then, by the time you get to Node B or C, what you did on A is already there. Imagine some sort of distributed industrial control scenario, perhaps.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt">Jim Lux<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">SunRISE Project Manager<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">Jet Propulsion Lab<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">+1(818)354-2075 (office)<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">+1(818)395-2714 (cell)<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"> <o:p></o:p></span></p>
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