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If at first you don't ...If at first you don't ...Posted Jul 5, 2007 19:51 UTC (Thu) by filker0 (subscriber, #31278)Parent article: OLPC's software update problem
If the first OLPC software release contains a robust but resource intensive update distribution scheme (ie, the rsync based proposal) that does not scale well as the deployment grows, continued development on the mesh based scheme ought to continue full speed, and sent out to the OLPCs as updates once it's developed and tested. The two methods would have to co-exist on the servers for a while, but the load from the older method would decrease even as the number of deployed OLPC units goes up.
Someone (in another comment to a comment) compared one of the proposals outlined at the end of the article to bit torrent. On the surface, it is similar, however an OLPC will send the update packet to all of its peers, not just the ones that ask for it, and peers receiving the update packet passively need not acknowlege or retransmit the packet (except in the sense required by the mesh). A single transmitted packet might reach many peers, as it's a multicast; bit-torrent uses unicast, and puts a higher load on the network bandwidth for multiple (>2) peers.
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If at first you don't ... Posted Jul 6, 2007 13:39 UTC (Fri) by lamikr (subscriber, #2289) [Link] There are however couple of issues to think about in situation where the system is automatically accepting packages from the other machines in the network.- how to make sure that the system is able to save all packages advertized. (for example what happens if new packages will require 150 mb in size even without extracting them and one has only left about 100 mb) - how to prevent someone to make malicious local laptop which advertizes some bad applications for other local OLPC laptops. Should every single chunk of the apps be signed, if yes, then the verification of those chunks will also require some cpu... - some kind of cleaner is needed to make sure that old "uploads" are removed from wasting space, once there is already newer version coming or installed. (situation where you have received 30 % from glib 2.18.14 when that is updated again to something like glib 2.18.15)
I know those are all doable, but making them 100 % bullet proof is not easy task.
Mika
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