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10.22 Storage Element Depopulation Feature Set
10.22.1 Overview
The Storage Element Depopulation feature set provides a mechanism for a host to depopulate a storage element
from a device (i.e., make a specified storage element inaccessible for user data).
The media in a device may consist of a number of storage elements. Each of these storage elements:
a) is associated with some number of physical sectors; and
b) has a health status (see Section 12.10).
A storage element is a type of physical element. Physical elements are associated with a unique element identifier
that is assigned by the device. The element identifier shall be non-zero. The association of element identifiers to
physical elements shall persist across all resets. Activating microcode may change the association between element
identifiers and physical elements.
The health status of a given element may become degraded (i.e., outside manufacturer’s specification limit). Such
degradation may affect the overall performance of the device as seen by the host.
10.22.2 Status Change Notification
The device may monitor the status of storage elements as a background operation. The device may notify the host
that the status of one or more storage elements is not within manufacturer’s specification limit (see Section
12.10.6.7.5). The device notifies the host of the change in status of a storage element by incrementing the value in
the PHYSICAL ELEMENT STATUS CHANGED field (see Section 12.21.3.4).
To determine the status of storage elements, the host requests physical element status (see Section 12.10).
10.22.3
Repurposing Depopulation
10.22.3.1 Overview
Repurposing depopulation uses the REMOVE ELEMENT AND TRUNCATE command to perform the actions
specified in Section 10.22.3.3 to reduce the capacity of the device.
Upon completion of the REMOVE ELEMENT AND TRUNCATE command, the actions performed by repurposing
depopulation may continue as background processes. Upon the completion of the actions performed by repurposing
depopulation, the contents of the user data area may have no relation to the contents of the user data area before
the processing of the REMOVE ELEMENT AND TRUNCATE command. If any of the actions performed by
repurposing depopulation fails, then the device may abort subsequent media access commands with additional sense
code set to DEPOPULATION FAILED.
The device will maintain the current GList of the remaining elements.
A REMOVE ELEMENT AND TRUNCATE command may be issued for each storage element that is to be removed
from the current operating configuration. The effect of processing multiple REMOVE ELEMENT AND TRUNCATE
commands shall be cumulative.
This device limits the number of storage elements that may be depopulated to two. If the device is requested to
depopulate a storage element in excess of this limit, the device may return command aborted with the additional
sense code set to INVALID FIELD IN CDB.
The capacity values are reported by the IDENTIFY DEVICE command and the IDENTIFY DEVICE data log.
10.22.3.2 Actions Performed by Repurposing Depopulation
Repurposing depopulation uses the REMOVE ELEMENT AND TRUNCATE command, which specifies that the
device:
a) shall perform a depopulation operation;
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Hard Disk Drive Specification