[nvme2.0b 12] NVM capacity model

3.8NVM Capacity model

3.8.1 summary

NVM The subsystem can report NVM Capacity related information of multiple entities in the subsystem . This capacity reporting model includes NVM subsystem、 Domain （Domain, Please refer to the first 3.2.4 section ）、 Endurance group （Endurance Group, Please refer to the first 3.2.3 section ）、NVM Set（ Please refer to the first 3.2.2 section ）、 Namespace （namespace, Please refer to the first 3.2.1 section ） And media unit （Media Unit, See page 1.5.34 section ）.NVM The subsystem may support some 、 All or no such reports .

Figure 12 Shows NVM Used in subsystem to manage NVM The hierarchical relationship of the entities of capacity .

NVM Set The capacity in can be allocated to one or more namespaces , And each namespace exists entirely in the NVM Set in （ Please refer to the first 3.2.2 section ）. Is not NVM Set All capacity in the needs to be allocated to the namespace .

If the controller supports NVM Set, be Endurance Group The capacity in can be allocated to one or more NVM Set, And each NVM Set Completely existing in the Endurance Group in （ Please refer to the first 3.2.3 section ）. Is not Endurance Group All capacity in the needs to be allocated to NVM Set.

If the controller supports Endurance Groups And does not indicate support NVM Set, Then in all include NVMSETID In the data structure of the field ,NVMSETID The field should be cleared to 0h.

If the controller does not support Endurance Groups, Then in all include ENDGID In the data structure of the field ,ENDGID The field should be cleared to 0h.

If the controller supports Endurance Groups, The capacity in the domain can be allocated to one or more Endurance Groups, And each Endurance Group Completely exists in this domain （ Please refer to the first 3.2.4 section ）. Not all capacity in the domain needs to be allocated to Endurance Group.

NVM The subsystem can be based on Media Units The report Endurance Groups and NVM Set The composition of . Every Media Units Are assigned to one Endurance Group. If the support NVM Set, Then each Media Unit Are assigned to one NVM Set. Data is passed through Channels In and out Media Units. Every Media Units Are connected to one or more Channels. Every Channel Are connected to one or more Media Units.

Host use Capacity Management（ See also 8.3 section ） To allocate ：

1. Domain Capacity to Endurance Groups;
2. Endurance Group Capacity to NVM Sets;
3. Media Units to Endurance Groups; and
4. Media Units to NVM Sets,

As part of creating these entities .

Host use Namespace Management （ Please refer to the first 8.11 section ） Allocate capacity for the namespace .

3.8.2Media Unit Organization example of

Media Units The distribution of is used to organize NVM Physics in subsystems NVM Resources to meet specific performance The goal is . The following example shows a NVM Subsystem , It contains all the resources in a single domain . The domain has four Channels, Every Channel There are four of them Media Units.

3.8.2.1 ordinary NVM Subsystem

Figure 104 Shows a single field NVM Examples of subsystems , Which manages across all media units endurance.

performance The goal is maximum bandwidth , This is done by allowing each read or write Operation accesses all at the same time Media Units To achieve . all Media Units All in the same Endurance Group And the same NVM Set in .

Figure 104: Simple NVM Subsystem

Of this example Capacity Configuration Descriptor Contains a Endurance Group Configuration Descriptor.Endurance Group Configuration Descriptor Contains a NVM Set Identifier And four Channel Configuration Descriptors. Every Channel Configuration Descriptor Contains four Media Unit Configuration Descriptors. 3.8.2.2 Vertically organized NVM Subsystem

Figure 105 Shows a single domain NVM Examples of subsystems , among performance The goal is to pay for bandwidth in four NVM Sets And isolate them from each other .Endurance Manage individually for each group . Share a Channel Of Media Units Assigned to the same Endurance Group.Endurance Group All in Media Units All assigned to the same NVM Set. whatever NVM Set The bandwidth of may be less than or equal to this NVM Set Of Channel bandwidth .

Figure 105: Vertically-Organized NVM Subsystem

Of this example Capacity Configuration Descriptor Contains four Endurance Group Configuration Descriptors. Every Endurance Group Configuration Descriptor Contains a NVM Set Identifier And a Channel Configuration Descriptor. Every Channel Configuration Descriptor Contains four Media Unit Configuration Descriptors.

3.8.2.3 Horizontal organization of double NAND NVM Subsystem

Figure 106 Shows a single domain NVM Examples of subsystems , among Media Units Is able to act as QLC Or at a lower density NAND.Performance The goal is to act as SLC Running small NVM Set And as QLC Large operation NVM Set Provide maximum bandwidth .

Figure 106: Horizontally-Organized Dual NAND NVM Subsystem

Capacity Configuration Descriptor Will contain two Endurance Group Configuration Descriptors. The first of this example Endurance Group Configuration Descriptor：

• Express Capacity Adjustment Factor about 1,600;
• Contains a NVM Set Identifier;
• Contains four Channel Configuration Descriptors. Every Channel Configuration Descriptor Contains a Media Unit Configuration Descriptor.

The second of this example Endurance Group Configuration Descriptor：

• Express Capacity Adjustment Factor by 100;
• Contains a NVM Set Identifier;
• Contains four Channel Configuration Descriptors. Every Channel Configuration Descriptor Contains three Media Unit Configuration Descriptors.

3.8.3 Capacity report

For those that do not support multiple domains NVM Subsystem ,Identify Controller data structure Capacity information reported in （ namely Figure 275 Medium TNVMCAP Fields and UNVMCAP Field ） It describes NVM Capacity of subsystem . If MEGCAP Field is not 0, This field indicates that you can NVM The largest entity created in the subsystem （ for example ,Endurance Group、NVM Set、namespace）.

For those that support multiple domains NVM Subsystem ,Identify Controller data structure The capacity information reported in describes the processing Identify The capacity that the controller of the command can access . The host can use Identify Command access Domain List data structure（ Please refer to the first 5.17.2.17 section ） To determine which domains the controller can access and the capacity information of each domain . If Max Endurance Group Domain Capacity Field is not 0, Then this field describes that the controller can Domain Attributes Entry The largest entity created in the domain described （ for example ,Endurance Group、namespace）.

For support Endurance Groups Of NVM Subsystem （ Please refer to the first 3.2.3 section ）, The host can use Identify Command access Endurance Group List data structure（ Please refer to the first 5.17.2.18 section ） To determine which can be accessed by the controller Endurance Groups. Make sure each Endurance Group Capacity information , Host use Get Log Page Command access Endurance Group Information log page（ Please refer to the first 5.16.1.10 section ）.

For support NVM Set Of NVM Subsystem （ Please refer to the first 3.2.2 section ）, The host can use the identification command to access NVM Set List data structure （ Please refer to the first 5.17.2.4 section ） To determine what the host can access NVM Set Controller and each NVM Set Capacity information .

about Endurance Groups、NVM Sets And namespace management ,Figure 107 Describes support for NVM Sets、Endurance Groups and Domains The effect of , On these domains , Capacity information is used for each management operation .

Figure 107: Capacity Information Field Usage