Losing the entire system is. Environmental disasters are the prime candidates
for causing complete system loss.
Log shipping is an excellent mitigation technique for environmental, hardware, or
media-related disasters. It??™s superior to many other techniques because it requires no
information about the state of any other system (with one exception, which I??™ll get to
when I discuss architecture), it has no limitations to the number of servers acting as
standby databases, it has almost no resource overhead on the primary server, and you
can actually use the standby servers for read-only access. Let??™s look at each of these benefits
in detail.
Log Shipping Is Stateless
Mitigation techniques such as clustering and mirroring require a constant connection
between the primary and secondary servers to establish the state of each system. A constant,
repetitive conversation is occurring:
Primary server: Are you OK?
Secondary server: Yup, how about you?
Primary server: I??™m fine. Are you still OK?
CHAPTER 6 n MAINTAINING A WARM STANDBY SERVER VIA LOG SHIPPING 143
Secondary server: I said yes.
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