Novell EDIRECTORY 8.8 SP3, Administration Manual, Page: 552 / 634

552 Novell eDirectory 8.8 Administration Guide
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Figure 18-1
Advanced Referral Costing
Figure 18-1 illustrates an LDAP subtree search to Server A for cn=GHowe , starting at O=MyCorp .
However, the
cn=GHowe
object is located in the
ou=MidWest
partition, which is not represented
on Server A.
To locate a server that holds the data needed to fulfill the client request, Server A must either get the
data from Server B or Server C. To do this, Server A must send the request to either Server B or C.
Server A happens to choose Server B; the process of choosing server is unpredictable. Server B is
available on the network and accepts the request, but is unable to complete the request quickly,
resulting in Server A waiting for Server B even though Server C could also provide the required
data. Until Server B either fulfills the request or is no longer available on the network, the request
from Server A must wait.
The following sections provide information about how you can improve the performance of
eDirectory servers:
Š Section 18.4.1, “Improving Server-to-Server Connection,” on page 552
Š
Section 18.4.2, “Advantages of Referral Costing,” on page 554
Š Section 18.4.3, “Deploying ARC,” on page 555
Š
Section 18.4.4, “Enabling Advanced Referral Costing,” on page 556
Š Section 18.4.5, “Tuning Advanced Referral Costing,” on page 556
Š
Section 18.4.6, “Monitoring Advanced Referral Costing,” on page 557
18.4.1 Improving Server-to-Server Connection
Advanced Referral Costing (ARC) is an improved costing algorithm that is disabled by default. It is
available in eDirectory 8.7.3.9 and eDirectory 8.8.2. The main purpose of ARC is to prevent server
outages. Some of the benefits of ARC can include:
Š
Improved server performance and fault tolerance
Š Better server-to-server communications
Š
Load distribution
Š Remote server health monitoring
Š
Simplified isolation and identification of communication problems
Who Should Use ARC?
Servers that don't hold a local copy of an object or service need to walk the tree for information
benefit from ARC, because they frequently communicate with the other servers. ARC is very
effective in an LDAP environment, especially during prefer chaining.