Configuring model maintenance settings

You can modify settings for maintaining your data model, including aging limits, in the Model Maintenance settings of the user interface.

To configure model maintenance settings:

1. From the main menu, click the Administration icon.   

   The Administration page opens.

2. In the Model section, click Model Maintenance. 

   

   The options on the page are described in the following table.

   Field Name	Details
   Directly Discovered Data removal	Specify the age past which Discovery Accesses and all the related DDD nodes are removed (the default is 28 days). • Quarterly (90 days) • Monthly (28 days) • Fortnightly • Weekly If the setting does not match one of these options the value will be shown as "--custom settings--". In a demonstration appliance only, the default setting for aging is Never, meaning that demonstration data never ages out of the system. This setting is not available for any other type of appliance, and demonstration appliances should never be used for anything other than demonstrations. For guidelines, see Modifying DDD, host, and software instance aging limits. If you change this option, you must restart scanning for the changes to take effect.
   Import Record removal	Specify the age past which Import records are removed (the default is 28 days).  • Quarterly (90 days)  • Monthly (28 days)  • Fortnightly  • Weekly If you change this option, you must restart scanning for the changes to take effect.
   Time before destroyed nodes are purged	Specify the time elapsed before destroyed nodes are purged from the datastore. The default is one year. To change this, choose one of the following periods from the drop-down list. • Never • 30 days • 90 days • 180 days • One year • Two years
   Time before history entries are purged	Specify the time elapsed before history entries are purged from the datastore. The default is never. To change this, choose one of the following periods from the drop-down list. • Never • 30 days • 90 days • 180 days • One year • Two years If you are using a multi-generational datastore, history purging must be undertaken manually; the Time before history entries are purged setting has no effect. See purging the history for more information.
   Scan optimization timeout	When an IP address is designated the preferred IP address for a host, Discovery does not perform scans on other known IP addresses for that host. This is referred to as scan optimization. After a specified Scan optimization timeout period, Discovery will scan other known IP addresses for that host to ensure that they are still non-preferred and on the same host. BMC Discovery reuses the last successful credential until the Scan optimization timeout expires. It attempts to use other credentials afterwards. The default is seven days. Specify one of the following timeout periods from the drop-down list.  • 1 - 10 days • 14 days • 21 days
   Device aging time limit	Specify the aging time limit for host, network device, storage device, printer, SNMP managed device, mainframe, and management controller nodes. This value must be higher than the Scan optimization timeout. The default is 10 days. • 2 - 10 days • 14 days • 21 days • 28 days For guidelines, see Modifying DDD, host, and software instance aging limits.
   Device aging access failures	Specify the access failure limit for host, network device, storage device, printer, SNMP managed device, mainframe, and management controller nodes. The default is seven failures. • 1 - 10 failures
   Time to elapse before a software instance/container/virtual machine/runtime environment/storage can be aged	Specify the time to elapse before a software instance/container/virtual machine/runtime environment/storage node can be aged. The default is 10 days. • 1 - 20 days • Steps of 5 to 100 days For guidelines, see Modifying DDD, host, and software instance aging limits.
   Minimum number of failed accesses before a software instance/container/virtual machine/runtime environment/storage is aged	Failed accesses before a software instance/container/virtual machine/runtime environment/storage node is aged. • 1 - 20 failures • Steps of 5 to 45 failures
   Number of credential failures that count as one failed access	In situations where a credential on a host (or network device, printer, and so on) is changed on the host but the corresponding access credential is not updated in BMC Discovery, the host or device might age out of the model quite quickly, although it is still there and responding, though BMC Discovery cannot access it. This option slows down the device aging (Device aging access failures above). For example, using the default of five, the device becomes eligible to age out after five times the value of Device aging access failures (5 * 7 = 35). The elapsed time limit (Device aging time limit above) is still respected. If there is no response from the device, aging occurs normally. The default is five failures. Specify one of the following from the drop-down list. • 1 failure • 2 failures • 3 failures ... • 10 failures
   Size Warning	The maximum size of the datastore. When this limit is reached, a warning is displayed in the Appliance Status page. This is a soft limit and does not prevent the datastore growing beyond the specified limit. You can select any value from 10 to 100 GB in steps of 5 GB from the list. The default is 30 GB.
   Checkpoint Interval	The interval between datastore checkpoints. The larger the interval, the more data has to be written to the checkpoint files. The smaller the interval, less data needs to be written to the checkpoint files, though the writing takes place more often. The default is 15 minutes. You must contact Customer Support before you make any changes to this setting.
   Replication Factor Limit	In a cluster, the replication factor is set automatically according to the number of members in the cluster: • For 2 to 8 members, the replication factor is 2. • 9 - 15 members, the replication factor is 3. • 16+ members, the replication factor is 4. In large clusters, where performance has been a problem, it might be improved by limiting the replication factor. This only has an effect on clusters with nine or more members. Select one of the limits from the drop-down list: • None - based on cluster size - the default behavior • Always 2 copies • Up to 3 copies The changes only take effect after a configuration change is performed on the cluster. The replication factor change always causes a cluster rebalance which is a time consuming operation on large clusters.

For information on how host aging works in BMC Discovery, see the following video (03:34):

 https://youtu.be/qIO5G2AE714

Modifying DDD, host, and software instance aging limits 

In general, the expectation that BMC Discovery uses for deriving the default model maintenance settings is based on performing one scan of the estate every 24 hours with a DDD depth of one month. This expectation is also used to derive the sizing data.The default setting for data aging for both hosts and software instances is 10 days, because for most deployments this limit provides the best balance of responsiveness without data thrashing. Putting this in a business example, this gives two weekends plus additional time to detect that a host is aging, investigate why it is doing so, and make changes before the host is destroyed. It gives the software teams the same length of time to sort out any failures in the estate.

However, there might be occasions when modifying the defaults are necessary, particularly if you scan your estate at different intervals and need to keep close control on disk consumption. The following table shows recommended settings based on your scanning frequency.