CI reclassification is the process of changing the class of a CI in the CMDB based on the discovery data. It can be done manually or automatically, depending on the configuration settings. CI reclassification can result in data loss if the new class has fewer or different attributes than the original class, and the existing attribute values are not preserved or mapped to the new class. This can happen when a CI is switched to a different class hierarchy, such as from a Linux Server to a Windows Server, or when a CI is downgraded to a less specific class, such as from a Database to a Software Instance. Therefore, switching and downgrading have a higher chance of leading to lost data during CI reclassification.
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CI reclassification
Reclassify CIs
Configure automatic CI reclassification

The default thread count for a MID Server is 25. This means that the MID Server can run up to 25 worker threads simultaneously to execute the jobs assigned to it by the ServiceNow instance. The worker threads are divided into different thread pools based on the priority of the jobs. The MID Server can also adjust the thread count dynamically based on the system resources and the workload. The thread count can be configured by changing the MID Server parameters in the ServiceNow instance12. References = 1: MID Server Max Threads - Worker Groups - Priority and Queues - ServiceNow 2: Product Documentation | ServiceNow

A horizontal discovery pattern is a set of steps that execute operations to identify, classify, and populate attributes for configuration items (CIs) of a specific category or class, such as infrastructure or application. A horizontal pattern can be applied to any operating system or platform that supports the required protocols and commands12.
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Horizontal discovery patterns
Discovery pattern types

The Credential Affinity table is a table that associates an IP address and a credential in Discovery1. It is used to store the credential that was successfully used to access a device during Discovery2. It can also be used to manually assign a credential to an IP address or a range of IP addresses3. The other options are not tables that associate an IP address and a credential in Discovery. The Service Affinity table is a table that associates a business service and a credential. The Service CI Association table is a table that associates a business service and a configuration item (CI). The Tags table is a table that stores tags that can be applied to records in any table.
1: Credential Affinity table 2: Credential affinity 3: Manually assign a credential to an IP address : Service Affinity table : Service CI Association table : Tags table

The mid.discovery.max_pattern_payload_size property defines the maximum overall size for the returned payload that comes from patterns. This property is set on the MID Server and applies to all patterns that run on that MID Server. If the payload size exceeds this limit, the pattern execution fails and an error message is logged in the ECC queue. The default value of this property is 10 MB1.
1: ServiceNow Docs - MID Server properties for Discovery and Service Mapping 2: ServiceNow Docs - Discovery payload size and processing