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This architecture allows you to add more machines to a cluster of machines, which
in turn adds more overall horsepower to the system. But there was a problem with
the implementation of this architecture for OPS, stemming from the fact that a page
can contain more than a single row. If one machine in a cluster wanted to modify a
row in a page that was already being modified by another machine, that page had to
be flushed to the database file on the shared disk??”a scenario that was termed a ping.
This chain of events caused extra disk I/O, which in turn decreased the overall performance
of the solution.
The traditional way around this problem was simply to avoid it??”to use OPS only
when a database would not cause pings with a lot of write operations, or to segregate
writes so that they would not require data in use on another node. This
limitation required you to carefully consider the type of application to which you
would deploy OPS and sometimes forced you to actually modify the design of your
application to work around OPS??™s limitations.


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