On Fri, 19 Jun 2009, Matt Lawrence wrote: > On Fri, 19 Jun 2009, [email protected] wrote: > >> On Fri, 19 Jun 2009, Derek J. Balling wrote: >> >> remember that one significant performance bottleneck on current systems is >> the rate at which the various portions of memory (cache) >> _in_the_same_chip_ can propogate updates, and significant performance >> improvements happen by people refactoring things so that it's not >> nessasary to access the same memory from two different cores at the same >> time. >> >> with vmware failover you not only need to go down through several layers >> of cache out to the ram, you then need to go out the PCI buss to the >> network card, over the network to the other machine. >> >> it's not _possible_ to replicate all memory writes in real time to another >> machine with commodity hardware (or with anything close to the same >> performance even on custom hardware) > > You don't have to. As long as you have the memory state at the end of the > last destructive I/O operation, you can just play everything forward from > that point.
the definition of 'last destructive I/O operation' is very slippery, it could consist of sending a network packet (and therefor updating the tcp sequence number) David Lang > -- Matt > It's not what I know that counts. > It's what I can remember in time to use. > _______________________________________________ > Discuss mailing list > [email protected] > http://lopsa.org/cgi-bin/mailman/listinfo/discuss > This list provided by the League of Professional System Administrators > http://lopsa.org/ > _______________________________________________ Discuss mailing list [email protected] http://lopsa.org/cgi-bin/mailman/listinfo/discuss This list provided by the League of Professional System Administrators http://lopsa.org/
