The core table that requires migration when extending ITSM Asset Management with Hardware Asset Management is the alm_asset table1.
The alm_asset table stores the records of all the assets in the system, regardless of their type or class1.
When you activate the Hardware Asset Management plugin, a migration script runs that converts the existing asset records in the alm_asset table to hardware asset records in the alm_hardware table2.
The alm_hardware table is a child table of the alm_asset table that stores the records of the hardware assets only2.
The migration script also updates the references and relationships of the migrated assets to the new table2.
The migration script runs only once and does not affect the future creation or update of asset records2. Reference:
Asset table - Product Documentation: San Diego - ServiceNow
Hardware Asset Management - Product Documentation: Tokyo - ServiceNow

* The current value of an asset is the amount that the asset is worth at the present time, based on its original cost and the accumulated depreciation1.
* The current value of an asset is also known as the residual value or the book value12.
* The residual value is the estimated value of the asset at the end of its useful life2.
* The residual value is used to calculate the depreciation expense of the asset over its useful life2.
* The residual value is different from the salvage value, which is the estimated value of the asset if it is sold or disposed of2.
* The cost of ownership is the total amount of money spent on acquiring, maintaining, and operating an asset over its lifetime3.
* The current balance is the amount of money available in an account at a given time4.
References: 1: Asset depreciation 2: Depreciation 3: Cost of ownership 4: Current balance

Hardware model normalization is a feature that enables users to normalize the details, such as manufacturer, product, model, and device type, of hardware and consumable models1 Hardware model normalization uses the data from the models and compares it against the data in the Hardware Model Normalization Content Service, which is a cloud-based service that provides standardized and enriched information about hardware models1 Hardware model normalization sets the normalized display name for each model record based on three attributes: Name, Manufacturer, and Model number2 The Model Management tab of the Hardware Asset dashboard shows the status of the hardware models in the Product Catalog, such as Matched, Match Not Found, or Not Normalized3 Several of your models are listed as Match Not Found on the Model Management tab of the Hardware Asset dashboard. This means that the normalization process could not find a matching rule in the Content Service for those models3 The potential causes of this are34:
The hardware model content has not yet been downloaded from the Content Service. The Content Service is updated periodically with new and updated rules for hardware models. You need to download the latest content from the Content Service to ensure that your models are normalized with the most accurate and complete information. You can download the content manually or schedule it to run automatically.
Normalization could not match any of the three key fields in the hardware model form with a rule in the Content Service. The three key fields are Name, Manufacturer, and Model number. If any of these fields are missing, incorrect, or inconsistent with the data in the Content Service, the normalization process will fail to find a matching rule. You need to review and correct the data in these fields to ensure that they match the data in the Content Service.
A normalization rule for the hardware model does not exist in the Content Service. The Content Service may not have a rule for some hardware models, especially if they are new, rare, or custom-made. In this case, you can create a custom rule for the hardware model in the Hardware Model Normalization Rules module, or submit a request to the Content Service team to add a rule for the hardware model.