Why, When, and How Often Should You Do Health Checks?

     

Do you keep tabs on the noises that your car makes and notes what is normal and what is not? Do you change the oil regularly, check the various fluid levels, and monitor the tires for wear and tear? Of course you do. You know you must take good care of your car, or problems can (and do) happen. If not detected early, these problems can be very expensive to repair in terms of both time and money. Your directory services (DS) tree is no different from your car in this regard.

A network administrator's role is to ensure a healthy and working environment so all users can access shared resources quickly when they need them. Unfortunately, users generally only retain memories of the times when the network is unavailable and not of the times the network is running flawlessly. Therefore, it is your responsibility to make sure your network runs like clockwork, and you should perform regular DS health checks to ensure this.

Depending on the environment, the frequency of health checks varies between perhaps once per week to once per quarter. The frequency of health checks depends on whether you the tree is static or dynamic. To determine whether you have a dynamic tree or static tree, consider the following definitions:

• Static DS tree ” A static tree has minimal routine changes. For example, you only make simple changes such as adding or deleting user objects, or you create a partition or add a server every couple months. Because you make fewer changes to a static DS tree than to a dynamic one, you only need to perform DS health checks infrequently.

• Dynamic DS tree ” A dynamic tree sees frequent nonroutine changes. For example, you create a partition or add a server weekly, or you are in the process of developing the tree.

If you have a dynamic DS tree, you should perform a DS health check once per week or whenever a major change is about to be made. However, as the pace of change decreases and the DS tree becomes more static, you can relax a little and perform DS health checks less frequently. Table 13.1 shows some general guidelines for the frequency of performing a DS tree health check tasks .

Table 13.1. Recommended NDS/eDirectory Health Check Task Frequency

DS HEALTH CHECK TASK	FREQUENCY
DS versions check	Monthly or quarterly
Time synchronization check	Monthly or every two months
DS (server-to-server) synchronization status check	Monthly
Replica synchronization (partition continuity) check	Monthly
Backlink/external references check	Monthly
Obituaries check	Monthly
Replica state check	Monthly or quarterly
Replica ring consistency check	Monthly or quarterly
Schema sync status check	Quarterly
Partition size check	Quarterly
Renamed and unknown object check	Monthly or quarterly
Schema consistency check	Quarterly or after a schema extension operation
Duplicate tree name check	Monthly or quarterly
DS tunable parameter check	Quarterly
eDirectory cache statistics check	Monthly or bimonthly

The first four tasks in Table 13.1 are considered basic DS tree health check steps. If you do not perform the full health check, these are the minimal checks that should be performed.

TIP

Not only should you perform regular health checks as preventive measures, but you should perform a health check on the DS tree before you execute a major DS operation such as moving or deleting large numbers of objects, performing a partition operation, or adding or deleting servers.