Novell EDIRECTORY 8.8 SP3, Administration Manual, Page: 557 / 634

Maintaining Novell eDirectory 557
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server, and also detects if a server is now less busy, or is healthy, so a client doesn't need to suffer
adverse effects to check the server's health. There are two permanent configuration parameters that
can be changed for the background thread:
Š
ARC_MAX_WAIT: How stale a timer is before a request to the server to check its health (180
seconds by default).
Š ARC_BG_INTERVAL: How often the background thread runs (60 seconds by default,: 0
means disabled and the thread doesn't run).
For additional information, see section 8.4.24 setting permanent configuration parameters.
Remote Health Information
Servers using ARC periodically request health information from a remote server. These are not
additional requests on the wire, but additional health information that is returned in standard resolve
name requests that servers frequently make. This information is then used in the costing algorithm to
further enhance reactions to servers that are under heavy loads. When a resolve name request is
being made to a remote server, if it has been more than 15 seconds since the last update, health
information is requested from the remote server and is added to the reply of the resolve name
request.
There is one tunable parameter for Remote Health Monitoring:
Š
ARC_DS_INFO_INTERVAL: This is how often to request lock (health) information in ARC
(15 seconds by default).
18.4.6 Monitoring Advanced Referral Costing
You can print the ResolveTimes table to observe Advanced Referral Costing in action.
Use the following commands to print the ResolveTimes table:
Š
set DSTRACE = +DBG
Š set DSTRACE = !ARC
This prints the Resolve Times table and the current stored information for each server. It shows the
transport address, the milliseconds since the address was last used, the last cost that was used in a
referral decision, and the number of outstanding requests for that address.
A high number of outstanding requests is not necessarily a problem. It might simply mean that that
server is used frequently.
Using ARC for Troubleshooting
One of the most useful features of ARC is the ability to quickly identify communication problems
with servers.
The following is an example of a ResolveTimesTable printout:
ARC is currently enabled.