'\" t
.\"     Title: nvme-read
.\"    Author: [FIXME: author] [see http://www.docbook.org/tdg5/en/html/author]
.\" Generator: DocBook XSL Stylesheets vsnapshot <http://docbook.sf.net/>
.\"      Date: 04/24/2020
.\"    Manual: NVMe Manual
.\"    Source: NVMe
.\"  Language: English
.\"
.TH "NVME\-READ" "1" "04/24/2020" "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 <device> [\-\-start\-block=<slba> | \-s <slba>]
                        [\-\-block\-count=<nlb> | \-c <nlb>]
                        [\-\-data\-size=<size> | \-z <size>]
                        [\-\-metadata\-size=<size> | \-y <size>]
                        [\-\-ref\-tag=<reftag> | \-r <reftag>]
                        [\-\-data=<data\-file> | \-d <data\-file>]
                        [\-\-metadata=<metadata\-file> | \-M <metadata\-file>]
                        [\-\-prinfo=<prinfo> | \-p <prinfo>]
                        [\-\-app\-tag\-mask=<appmask> | \-m <appmask>]
                        [\-\-app\-tag=<apptag> | \-a <apptag>]
                        [\-\-limited\-retry | \-l]
                        [\-\-force\-unit\-access | \-f]
                        [\-\-dir\-type=<type> | \-T <type>]
                        [\-\-dir\-spec=<spec> | \-S <spec>]
                        [\-\-dsm=<dsm> | \-D <dsm>]
                        [\-\-show\-command | \-v]
                        [\-\-dry\-run | \-w]
                        [\-\-latency | \-t]
.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=<slba>, \-s <slba>
.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=<size>, \-z <size>
.RS 4
Size of data, in bytes\&.
.RE
.PP
\-\-metadata\-size=<size>, \-y <size>
.RS 4
Size of metadata in bytes\&.
.RE
.PP
\-\-data=<data\-file>, \-d <data\-file>
.RS 4
Data file\&. If none provided, contents are sent to STDOUT\&.
.RE
.PP
\-\-metadata=<metadata\-file>, \-M <metadata\-file>
.RS 4
Metadata file, if necessary\&.
.RE
.PP
\-\-prinfo=<prinfo>, \-p <prinfo>
.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=<reftag>, \-r <reftag>
.RS 4
Optional reftag when used with protection information\&.
.RE
.PP
\-\-app\-tag\-mask=<appmask>, \-m <appmask>
.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 <type>, \-\-dir\-type=<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 specifcation (1\&.3a) defines only one directive, 01h, for write stream idenfiers\&.
.RE
.PP
\-S <spec>, \-\-dir\-spec=<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>, \-\-dsm=<dsm>
.RS 4
The optional data set management attributes for this command\&. The argument for this is the lower 16 bits of the DSM field in a write command; the upper 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
.SH "EXAMPLES"
.sp
No examples yet\&.
.SH "NVME"
.sp
Part of the nvme\-user suite