NVME_IDENTIFY_NAMESPACE_DATA structure (nvme.h)

Article
03/13/2023

Contains values that indicate capabilities and settings that are specific to a particular namespace.

The capabilities and settings that are common to all namespaces are contained in the NVME_IDENTIFY_NAMESPACE_DATA data structure for the namespace with the Namespace Identifier of 0xFFFFFFFF.

The nvme.h header file defines the constant NVME_NAMESPACE_ALL with a value of 0xFFFFFFFF.

If the controller supports Namespace Management and the Namespace Identifier (NSID) field of the NVME_COMMAND structure is set to NVME_NAMESPACE_ALL, the controller returns an NVME_IDENTIFY_NAMESPACE_DATA data structure that specifies capabilities that are common across all namespaces.

Syntax

typedef struct {
  ULONGLONG                    NSZE;
  ULONGLONG                    NCAP;
  ULONGLONG                    NUSE;
  struct {
    UCHAR ThinProvisioning : 1;
    UCHAR NameSpaceAtomicWriteUnit : 1;
    UCHAR DeallocatedOrUnwrittenError : 1;
    UCHAR SkipReuseUI : 1;
    UCHAR NameSpaceIoOptimization : 1;
    UCHAR Reserved : 3;
  } NSFEAT;
  UCHAR                        NLBAF;
  struct {
    UCHAR LbaFormatIndex : 4;
    UCHAR MetadataInExtendedDataLBA : 1;
    UCHAR Reserved : 3;
  } FLBAS;
  struct {
    UCHAR MetadataInExtendedDataLBA : 1;
    UCHAR MetadataInSeparateBuffer : 1;
    UCHAR Reserved : 6;
  } MC;
  struct {
    UCHAR ProtectionInfoType1 : 1;
    UCHAR ProtectionInfoType2 : 1;
    UCHAR ProtectionInfoType3 : 1;
    UCHAR InfoAtBeginningOfMetadata : 1;
    UCHAR InfoAtEndOfMetadata : 1;
    UCHAR Reserved : 3;
  } DPC;
  struct {
    UCHAR ProtectionInfoTypeEnabled : 3;
    UCHAR InfoAtBeginningOfMetadata : 1;
    UCHAR Reserved : 4;
  } DPS;
  struct {
    UCHAR SharedNameSpace : 1;
    UCHAR Reserved : 7;
  } NMIC;
  NVM_RESERVATION_CAPABILITIES RESCAP;
  struct {
    UCHAR PercentageRemained : 7;
    UCHAR Supported : 1;
  } FPI;
  struct {
    UCHAR ReadBehavior : 3;
    UCHAR WriteZeroes : 1;
    UCHAR GuardFieldWithCRC : 1;
    UCHAR Reserved : 3;
  } DLFEAT;
  USHORT                       NAWUN;
  USHORT                       NAWUPF;
  USHORT                       NACWU;
  USHORT                       NABSN;
  USHORT                       NABO;
  USHORT                       NABSPF;
  USHORT                       NOIOB;
  UCHAR                        NVMCAP[16];
  USHORT                       NPWG;
  USHORT                       NPWA;
  USHORT                       NPDG;
  USHORT                       NPDA;
  USHORT                       NOWS;
  USHORT                       MSSRL;
  ULONG                        MCL;
  UCHAR                        MSRC;
  UCHAR                        Reserved2[11];
  ULONG                        ANAGRPID;
  UCHAR                        Reserved3[3];
  struct {
    UCHAR WriteProtected : 1;
    UCHAR Reserved : 7;
  } NSATTR;
  USHORT                       NVMSETID;
  USHORT                       ENDGID;
  UCHAR                        NGUID[16];
  UCHAR                        EUI64[8];
  NVME_LBA_FORMAT              LBAF[16];
  UCHAR                        Reserved4[192];
  UCHAR                        VS[3712];
} NVME_IDENTIFY_NAMESPACE_DATA, *PNVME_IDENTIFY_NAMESPACE_DATA;

Members

NSZE

Indicates the total size of the namespace in logical blocks.

A namespace of size n consists of Logical Block Address (LBA) 0 through (n - 1). The number of logical blocks is based on the formatted LBA size. This field is undefined prior to the namespace being formatted.

NCAP

Indicates the maximum number of logical blocks that may be allocated in the namespace at any point in time.

The number of logical blocks is based on the formatted LBA size. This field is undefined prior to the namespace being formatted.

The NCAP field is used in the case of thin provisioning and reports a value that is smaller than or equal to the Namespace Size (NSZE).

Spare LBAs are not reported as part of this field. A value of 0h for the Namespace Capacity (NCAP) indicates that the namespace ID is an inactive namespace ID. A logical block is allocated when it is written with a Write or Write Uncorrectable command. A logical block may be deallocated using the Dataset Management command.

NUSE

Indicates the current number of logical blocks allocated in the namespace.

The value of this field is smaller than or equal to the value of the Namespace Capacity NCAP field.

The number of logical blocks is based on the formatted LBA size. When using the NVM command set: A logical block is allocated when it is written with a Write or Write Uncorrectable command. A logical block may be deallocated using the Dataset Management command.

A controller may report a NUSE value equal to an NCAP value at all times if the product is not targeted for thin provisioning environments.

NSFEAT

A Namespace Features (NSFEAT) structure containing fields that define features of the namespace.

NSFEAT.ThinProvisioning

Bit 0 of the NSFEAT structure indicates whether the namespace supports thin provisioning.

When this value is set to 1, the namespace supports thin provisioning. Specifically, the Namespace Capacity (NCAP) reported may be less than the Namespace Size (NSZE). When this feature is supported and the Dataset Management command is supported, then deallocating LBAs will be reflected in the Namespace Utilization (NUSE) field.

When this value is cleared to 0, it indicates that thin provisioning is not supported and the NSZE and NCAP fields report the same value.

NSFEAT.NameSpaceAtomicWriteUnit

Bit 1 of the NSFEAT structure indicates whether Namespace Atomic Boundary Parameters are defined for this namespace.

When this value is set to 1, the fields NAWUN, NAWUPF, and NACWU are defined for this namespace and should be used by the host for this namespace instead of the AWUN, AWUPF, and ACWU fields in the Identify Controller data structure.

When this value is cleared to 0, the controller does not support the fields NAWUN, NAWUPF, and NACWU for this namespace. In this case, the host should use the AWUN, AWUPF, and ACWU fields defined in the Identify Controller data structure.

NSFEAT.DeallocatedOrUnwrittenError

Bit 2 of the NSFEAT structure indicates whether the controller supports the Deallocated or Unwritten Logical Block error for this namespace.

When this value is set to 1, the controller supports the Deallocated or Unwritten Logical Block (NVME_STATUS_NVM_DEALLOCATED_OR_UNWRITTEN_LOGICAL_BLOCK) error for this namespace. When this value is cleared to 0, the controller does not support the NVME_STATUS_NVM_DEALLOCATED_OR_UNWRITTEN_LOGICAL_BLOCK error for this namespace.

NSFEAT.SkipReuseUI

Bit 3 of the NSFEAT structure is a setting for the Skip Reuse UI feature.

NSFEAT.NameSpaceIoOptimization

NSFEAT.Reserved

Bits 4:7 of the NSFEAT structure are reserved.

NLBAF

Defines the number of supported LBA data size and metadata size combinations supported by the namespace.

LBA formats are allocated in order (starting with 0) and packed sequentially. This is a 0’s based value. The maximum number of LBA formats that may be indicated as supported is 16.

The supported LBA formats are indicated in the LBAF field (bytes 128 – 191 of this data structure). The metadata may be either transferred as part of the LBA (creating an extended LBA which is a larger LBA size that is exposed to the application) or it may be transferred as a separate contiguous buffer of data. The metadata cannot be split between the LBA and a separate metadata buffer.

It is recommended that software and controllers transition to an LBA size that is 4KB or larger for ECC efficiency at the controller. If providing metadata, it is recommended that at least 8 bytes are provided per logical block to enable use with end-to-end data protection.

FLBAS

A Formatted LBA Size (FLBAS) structure containing fields that indicate the LBA data size and metadata size combination that the namespace has been formatted with.

FLBAS.LbaFormatIndex

Bits 0:3 of the FLBAS structure specify one of the 16 supported LBA Formats indicated in this data structure.

FLBAS.MetadataInExtendedDataLBA

Bit 4 of the FLBAS structure indicates whether metadata is transferred at the end of the data LBA, creating an extended data LBA.

When this value is set to 1, the metadata is transferred at the end of the data LBA, creating an extended data LBA. When this value is cleared to 0, it indicates that all of the metadata for a command is transferred as a separate contiguous buffer of data.

Bit 4 is not applicable when there is no metadata.

FLBAS.Reserved

Bits 5:7 of the FLBAS structure are reserved.

MC

A Metadata Capabilities (MC) structure containing fields that indicate the capabilities for metadata.

MC.MetadataInExtendedDataLBA

Bit 0 of the MC structure indicates whether the namespace supports the metadata being transferred as part of an extended data LBA.

When this value is set to 1, the namespace supports the metadata being transferred as part of an extended data LBA. When this value is cleared to 0, it indicates that the namespace does not support the metadata being transferred as part of an extended data LBA.

MC.MetadataInSeparateBuffer

Bit 1 of the MC structure indicates whether the namespace supports the metadata being transferred as part of a separate buffer.

When this value is set to 1, the namespace supports the metadata being transferred as part of a separate buffer that is specified in the Metadata Pointer (MPTR) field of the Command structure. When this value is cleared to 0, the namespace does not support the metadata being transferred as part of a separate buffer.

MC.Reserved

Bits 7:2 of the MC structure are reserved.

DPC

An End-to-end Data Protection Capabilities (DPC) structure containing fields that indicate the capabilities for the end-to-end data protection feature.

Multiple bits may be set in this field.

DPC.ProtectionInfoType1

Bit 0 of the DPC structure indicates whether the namespace supports Protection Information Type 1.

When this value is set to 1, the namespace supports Protection Information Type 1. When this value is cleared to 0, the namespace does not support Protection Information Type 1.

DPC.ProtectionInfoType2

Bit 1 of the DPC structure indicates whether the namespace supports Protection Information Type 2.

When this value is set to 1, the namespace supports Protection Information Type 2. When this value is cleared to 0, the namespace does not support Protection Information Type 2.

DPC.ProtectionInfoType3

Bit 2 of the DPC structure indicates whether the namespace supports Protection Information Type 3.

When this value is set to 1, the namespace supports Protection Information Type 3. When this value is cleared to 0, the namespace does not support Protection Information Type 3.

DPC.InfoAtBeginningOfMetadata

Bit 3 of the DPC structure indicates whether the namespace supports protection information transferred as the first eight bytes of metadata.

When this value is set to 1, the namespace supports protection information transferred as the first eight bytes of metadata. When this value is cleared to 0, the namespace does not support protection information transferred as the first eight bytes of metadata.

DPC.InfoAtEndOfMetadata

Bit 4 of the DPC structure indicates whether the namespace supports protection information transferred as the last eight bytes of metadata.

When this value is set to 1, the namespace supports protection information transferred as the last eight bytes of metadata. When this value is cleared to 0, the namespace does not support protection information transferred as the last eight bytes of metadata.

DPC.Reserved

Bits 7:5 of the DPC structure are reserved.

DPS

A End-to-end Data Protection Type Settings (DPS) structure containing fields that indicate the Type settings for the end-to-end data protection feature.

NVME_PROTECTION_INFORMATION_TYPES

DPS.ProtectionInfoTypeEnabled

Bits 2:0 of the DPS structure is an NVME_PROTECTION_INFORMATION_TYPES value that indicates whether Protection Information is enabled and the type of Protection Information enabled.

DPS.InfoAtBeginningOfMetadata

Bit 3 of the DPS structure indicates whether the protection information, if enabled, is transferred as the first eight bytes of metadata.

When this value is set to 1, the protection information, if enabled, is transferred as the first eight bytes of metadata. When this value is cleared to 0, the protection information, if enabled, is transferred as the last eight bytes of metadata.

DPS.Reserved

Bits 7:4 of the DPS structure are reserved.

NMIC

A Namespace Multi-path I/O and Namespace Sharing Capabilities (NMIC) structure containing fields that specify the multi-path I/O and namespace sharing capabilities of the namespace.

NMIC.SharedNameSpace

Bit 0 of the NMIC structure indicates whether the namespace may be a shared namespace.

When this value is set to 1, the namespace may be accessible by two or more controllers in the NVM subsystem. When this value is cleared to 0, the namespace is a private namespace and may only be accessed by the controller that returned this namespace data structure.

NMIC.Reserved

Bits 7:1 of the NMIC structure are reserved.

RESCAP

A Reservation Capabilities (RESCAP) structure containing fields that specify the reservation capabilities of the namespace.

A value of 00h in this field indicates that reservations are not supported by this namespace.

FPI

A Format Progress Indicator (FPI) structure containing fields that indicate the percentage of the namespace that remains to be formatted when a format operation is in progress.

FPI.PercentageRemained

Bits 0:6 of the FPI structure indicate the percentage of the namespace that remains to be formatted. For example, a value of 25 indicates that 75% of the namespace has been formatted and 25% remains to be formatted.

A value of 0 indicates that the namespace is formatted with the format specified by the FLBAS and DPS fields in this data structure.

FPI.Supported

Bit 7 of the FPI structure indicates whether the namespace supports the Format Progress Indicator defined by the FPI.PercentageRemained field.

When this value is set to 1, the namespace supports the Format Progress Indicator defined by the FPI.PercentageRemained field. When this value is cleared to 0, the namespace does not support the Format Progress Indicator and the FPI.PercentageRemained field will be cleared to 0h.

DLFEAT

DLFEAT.ReadBehavior

DLFEAT.WriteZeroes

DLFEAT.GuardFieldWithCRC

DLFEAT.Reserved

NAWUN

Indicates the namespace specific size of the write operation guaranteed to be written atomically to the NVM during normal operation.

A value of 0h indicates that the size for this namespace is the same size as that reported in the AWUN field of the Identify Controller data structure. All other values specify a size in terms of logical blocks using the same encoding as the AWUN field.

NAWUPF

Indicates the namespace specific size of the write operation guaranteed to be written atomically to the NVM during a power fail or error condition.

A value of 0h indicates that the size for this namespace is the same size as that reported in the AWUPF field of the Identify Controller data structure. All other values specify a size in terms of logical blocks using the same encoding as the AWUPF field.

NACWU

Indicates the namespace specific size of the write operation guaranteed to be written atomically to the NVM for a Compare and Write fused command.

A value of 0h indicates that the size for this namespace is the same size as that reported in the ACWU field of the Identify Controller data structure. All other values specify a size in terms of logical blocks using the same encoding as the ACWU field.

NABSN

Indicates the atomic boundary size for this namespace for the NAWUN value.

This field is specified in logical blocks. Writes to this namespace that cross atomic boundaries are not guaranteed to be atomic to the NVM with respect to other read or write commands.

A value of 0h indicates that there are no atomic boundaries for normal write operations. All other values specify a size in terms of logical blocks using the same encoding as the AWUN field.

NABO

Indicates the Logical Block Address (LBA) on this namespace where the first atomic boundary starts.

If the NABSN and NABSPF fields are cleared to 0h, then the NABO field is cleared to 0h. The value of NABO should be less than or equal to NABSN and NABSPF.

NABSPF

Indicates the atomic boundary size for this namespace specific to the Namespace Atomic Write Unit Power Fail value.

This field is specified in logical blocks. Writes to this namespace that cross atomic boundaries are not guaranteed to be atomic with respect to other read or write commands and there is no guarantee of data returned on subsequent reads of the associated logical blocks.

A value of 0h indicates that there are no atomic boundaries for power fail or error conditions. All other values specify a size in terms of logical blocks using the same encoding as the AWUPF field.

NOIOB

Indicates the Namespace Optimal IO Boundary (NOIOB).

NVMCAP[16]

Indicates the total size of the NVM allocated to this namespace.

The value of this field is in bytes. This field is supported if the Namespace Management and Namespace Attachment commands are supported.

Note: This field may not correspond to the logical block size multiplied by the Namespace Size (NSZE) field. Due to thin provisioning or other settings (such as, endurance), this field may be larger or smaller than the NSZE reported.

NPWG

NPWA

NPDG

NPDA

NOWS

MSSRL

MCL

MSRC

Reserved2[11]

A reserved field.

ANAGRPID

Reserved3[3]

Bytes 192:383A are reserved.

NSATTR

NSATTR.WriteProtected

NSATTR.Reserved

NVMSETID

Indicates the Associated NVM Set Identifier (NVMSETID).

ENDGID

Indicates the Associated Endurance Group Identifier (ENDGID).

NGUID[16]

Contains a 128-bit value that is globally unique and assigned to the namespace when the namespace is created.

The Namespace Globally Unique Identifier (NGUID) field remains fixed throughout the life of the namespace and is preserved across namespace and controller operations (such as controller reset and namespace format).

This field uses the EUI-64 based 16-byte designator format.

Bytes 114:112 contain the 24-bit company_id value assigned by the IEEE Registration Authority.
Bytes 119:115 contain an extension identifer assigned by the corresponding organization.
Bytes 111:104 contain the vendor specific extension identifier assigned by the corresponding organization.

See the IEEE EUI-64 guidelines for more information. The controller should specify a globally unique namespace identifier in this field or the EUI64 field when the namespace is created.

EUI64[8]

Contains a 64-bit IEEE Extended Unique Identifier (EUI-64) that is globally unique and assigned to the namespace when the namespace is created.

The EUI64 field remains fixed throughout the life of the namespace and is preserved across namespace and controller operations (such as controller reset and namespace format).

The EUI-64 is a concatenation of a 24-bit or 36-bit company_id value assigned by the IEEE Registration Authority and an extension identifier assigned by the corresponding organization. See the IEEE EUI-64 guidelines for more information.

The controller should specify a globally unique namespace identifier in this field or the NGUID field when the namespace is created. If the controller is not able to allocate a globally unique 64-bit identifier then this field will be cleared to 0h.

LBAF[16]

Contains an array of 16 NVME_LBA_FORMAT structures. Each structure in the array specifies an LBA Format and indicates that it is supported by the controller.

The zero-based position of a structure in the array corresponds to the name of the LBA Format, such that LBA Format 0 (LBAF0) is in position 0, LBA Format 1 (LBAF1) is in position 1, and so on, up to LBA Format 15 (LBAF15) in position 15.

Reserved4[192]

VS[3712]

This range of bytes (384:4095) is allocated for Vendor Specific (VS) usage.

Requirements

Requirement	Value
Minimum supported client	Windows 10
Header	nvme.h

Share via

NVME_IDENTIFY_NAMESPACE_DATA structure (nvme.h)

Syntax

Members

Requirements

Feedback

Additional resources