'\" t
.\" Title: nvme-read
.\" Author: [FIXME: author] [see http://www.docbook.org/tdg5/en/html/author]
.\" Generator: DocBook XSL Stylesheets vsnapshot
.\" Date: 06/30/2023
.\" Manual: NVMe Manual
.\" Source: NVMe
.\" Language: English
.\"
.TH "NVME\-READ" "1" "06/30/2023" "NVMe" "NVMe Manual"
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.SH "NAME"
nvme-read \- Send an NVMe Read command, provide results
.SH "SYNOPSIS"
.sp
.nf
\fInvme\-read\fR [\-\-start\-block= | \-s ]
[\-\-block\-count= | \-c ]
[\-\-data\-size= | \-z ]
[\-\-metadata\-size= | \-y ]
[\-\-ref\-tag= | \-r ]
[\-\-data= | \-d ]
[\-\-metadata= | \-M ]
[\-\-prinfo= | \-p ]
[\-\-app\-tag\-mask= | \-m ]
[\-\-app\-tag= | \-a ]
[\-\-limited\-retry | \-l]
[\-\-force\-unit\-access | \-f]
[\-\-dir\-type= | \-T ]
[\-\-dir\-spec= | \-S ]
[\-\-dsm= | \-D ]
[\-\-show\-command | \-v]
[\-\-dry\-run | \-w]
[\-\-latency | \-t]
[\-\-storage\-tag | \-g ]
[\-\-storage\-tag\-check | \-C ]
[\-\-force]
.fi
.SH "DESCRIPTION"
.sp
The Read command reads the logical blocks specified by the command from the medium and copies to the data data buffer provided\&. Will use stdout by default if you don\(cqt provide a file\&.
.SH "OPTIONS"
.PP
\-\-start\-block=, \-s
.RS 4
Start block\&.
.RE
.PP
\-\-block\-count, \-c
.RS 4
The number of blocks to transfer\&. This is a zeroes based value to align with the kernel\(cqs use of this field\&. (ie\&. 0 means transfer 1 block)\&.
.RE
.PP
\-\-data\-size=, \-z
.RS 4
Size of data, in bytes\&.
.RE
.PP
\-\-metadata\-size=, \-y
.RS 4
Size of metadata in bytes\&.
.RE
.PP
\-\-data=, \-d
.RS 4
Data file\&. If none provided, contents are sent to STDOUT\&.
.RE
.PP
\-\-metadata=, \-M
.RS 4
Metadata file, if necessary\&.
.RE
.PP
\-\-prinfo=, \-p
.RS 4
Protection Information field definition\&.
.TS
allbox tab(:);
lt lt
lt lt
lt lt
lt lt
lt lt
lt lt.
T{
Bit
T}:T{
Description
T}
T{
3
T}:T{
PRACT: Protection Information Action\&. When set to 1, PI is stripped/inserted on read/write when the block format\(cqs metadata size is 8\&. When set to 0, metadata is passes\&.
T}
T{
2:0
T}:T{
PRCHK: Protection Information Check:
T}
T{
2
T}:T{
Set to 1 enables checking the guard tag
T}
T{
1
T}:T{
Set to 1 enables checking the application tag
T}
T{
0
T}:T{
Set to 1 enables checking the reference tag
T}
.TE
.sp 1
.RE
.PP
\-\-ref\-tag=, \-r
.RS 4
Optional reftag when used with protection information\&.
.RE
.PP
\-\-app\-tag\-mask=, \-m
.RS 4
Optional application tag mask when used with protection information\&.
.RE
.PP
\-\-force\-unit\-access, \-f
.RS 4
Set the force\-unit access flag\&.
.RE
.PP
\-T , \-\-dir\-type=
.RS 4
Optional directive type\&. The nvme\-cli only enforces the value be in the defined range for the directive type, though the NVMe specification (1\&.3a) defines only one directive, 01h, for write stream identifiers\&.
.RE
.PP
\-S , \-\-dir\-spec=
.RS 4
Optional field for directive specifics\&. When used with write streams, this value is defined to be the write stream identifier\&. The nvme\-cli will not validate the stream requested is within the controller\(cqs capabilities\&.
.RE
.PP
\-D , \-\-dsm=
.RS 4
The optional data set management attributes for this command\&. The argument for this is the least significant 8 bits of the DSM field in a write command; the most significant 16 bits of the field come from the directive specific field, if used\&. This may be used to set attributes for the LBAs being written, like access frequency, type, latency, among other things, as well as yet to be defined types\&. Please consult the NVMe specification for detailed breakdown of how to use this field\&.
.RE
.PP
\-v, \-\-show\-cmd
.RS 4
Print out the command to be sent\&.
.RE
.PP
\-w, \-\-dry\-run
.RS 4
Do not actually send the command\&. If want to use \-\-dry\-run option, \-\-show\-cmd option
\fImust\fR
be set\&. Otherwise \-\-dry\-run option will be
\fIignored\fR\&.
.RE
.PP
\-t, \-\-latency
.RS 4
Print out the latency the IOCTL took (in us)\&.
.RE
.PP
\-g , \-\-storage\-tag=
.RS 4
Variable Sized Expected Logical Block Storage Tag(ELBST)\&.
.RE
.PP
\-C, \-\-storage\-tag\-check
.RS 4
This flag enables Storage Tag field checking as part of end\-to\-end data protection processing\&.
.RE
.PP
\-\-force
.RS 4
Ignore namespace is currently busy and performed the operation even though\&.
.RE
.SH "EXAMPLES"
.sp
No examples yet\&.
.SH "NVME"
.sp
Part of the nvme\-user suite