On Thu, 2014-01-23 at 10:44 -0600, Andrew Deason wrote:
> > For example in an ideal world putting more or less DB servers in > > the client 'CellServDB' should not matter, as long as one that > > belongs to the cell is up; again if the logic were for all types > > of client: "scan quickly the list of potential DB servers, find > > one that is up and belongs to the cell and reckons is part of > > the quorum, and if necessary get from it the address of the sync > > site". The problem is that you the client to scan "quickly" to find a server that is up, but because networks are not perfectly reliable and drop packets all the time, it cannot know that a server is not up until that server has failed to respond to multiple retransmissions of the request. Those retransmissions cannot be sent "quickly"; in fact, they _must_ be sent with exponentially-increasing backoff times. Otherwise, when your network becomes congested, the retransmission of dropped packets will act as a runaway positive feedback loop, making the congestion worse and saturating the network. -- Jeff _______________________________________________ OpenAFS-info mailing list OpenAFS-info@openafs.org https://lists.openafs.org/mailman/listinfo/openafs-info
