LU-10918 llite: Rule based auto PCC caching when create files

[fs/lustre-release.git] / lustre / doc / lfs-mirror-create.1

diff --git a/lustre/doc/lfs-mirror-create.1 b/lustre/doc/lfs-mirror-create.1
index 31310af..28092fa 100644 (file)
--- a/lustre/doc/lfs-mirror-create.1
+++ b/lustre/doc/lfs-mirror-create.1
@@ -4,7 +4,7 @@ lfs mirror create \- create a mirrored file or directory
 .SH SYNOPSIS
 .B lfs mirror create
 <\fB\-\-mirror\-count\fR|\fB\-N\fR[\fImirror_count\fR]>
 .SH SYNOPSIS
 .B lfs mirror create
 <\fB\-\-mirror\-count\fR|\fB\-N\fR[\fImirror_count\fR]>

-.RI [ setstripe_options | \fB--parent ] ...
+[\fIsetstripe_options\fR|[\fB--flags\fR<=\fIflags\fR>]] ...

 .RI < filename | directory >
 .SH DESCRIPTION
 This command creates a mirrored file or directory specified by the path name
 .RI < filename | directory >
 .SH DESCRIPTION
 This command creates a mirrored file or directory specified by the path name


@@ -21,10 +21,9 @@ be a plain layout with specific striping pattern or a composite layout like
 Progressive File Layout (PFL) (see \fBlfs-setstripe\fR(1)).
 If \fIsetstripe_options\fR are not specified,
 then the stripe options inherited from the previous component will be used. If
 Progressive File Layout (PFL) (see \fBlfs-setstripe\fR(1)).
 If \fIsetstripe_options\fR are not specified,
 then the stripe options inherited from the previous component will be used. If

-there is no previous component or \fB\-\-parent\fR option is specified, then the
-default stripe options inherited from parent directory will be used. For stripe
-options, only \fIstripe_count\fR, \fIstripe_size\fR and OST \fIpool_name\fR can
-be inherited.
+there is no previous component, then the \fIstripe_count\fR and
+\fIstripe_size\fR options inherited from filesystem-wide default values will be
+used, and OST \fIpool_name\fR inherited from parent directory will be used.

 .br
 If no option is specified, then the command will return an error.
 .SH OPTIONS
 .br
 If no option is specified, then the command will return an error.
 .SH OPTIONS


@@ -41,14 +40,33 @@ The layout of one mirror. The options are the same as those for
 If \fIsetstripe_options\fR are not specified, then
 the stripe options inherited from the previous component will be used.
 .TP
 If \fIsetstripe_options\fR are not specified, then
 the stripe options inherited from the previous component will be used.
 .TP

-.B \-\-parent
-This option indicates that the default stripe options inherited from parent
-directory will be used.
+.B --flags<=\fIflags\fR>
+Where available \fIflags\fR are as follows:
+.RS
+.TP
+.BI prefer
+is supported in mirror creation. This flag will be set to all components that
+belong to ths corresponding mirror. The \fBprefer\fR flag gives hint to Lustre
+for which mirrors should be used to serve I/O. When a mirrored file is being
+read, the component(s) with \fBprefer\fR are likely to be picked to serve the
+read; and when a mirrored file is prepared to be written, the MDT will
+tend to choose the component with \fBprefer\fR flag set and stale the other
+components with overlapping extents. This flag just provides a hint to Lustre,
+which means Lustre may still choose mirrors without this flag set, for instance,
+if all preferred mirrors are unavailable when the I/O occurs. This flag could be
+set on multiple components.
+.LP
+Please note that this flag will be set to all components that belong to the
+corresponding mirror. There also exists option \fB--comp-flags\fR that can be
+set to individual components at mirror creation time.
+.RE

 .SH EXAMPLES
 .TP
 .B lfs mirror create -N2 /mnt/lustre/file1
 Create a mirrored file with 2 mirrors. Each mirror has the same default striping
 .SH EXAMPLES
 .TP
 .B lfs mirror create -N2 /mnt/lustre/file1
 Create a mirrored file with 2 mirrors. Each mirror has the same default striping

-pattern inherited from parent directory or filesystem-wide default.
+pattern with \fIstripe_count\fR and \fIstripe_size\fR inherited from
+filesystem-wide default values, and OST \fIpool_name\fR inherited from
+parent directory.

 .TP
 .B lfs mirror create -N2 -E 1M -E eof -c -1 /mnt/lustre/dir1
 Create a mirrored directory with 2 PFL mirrors. Each mirror has the same
 .TP
 .B lfs mirror create -N2 -E 1M -E eof -c -1 /mnt/lustre/dir1
 Create a mirrored directory with 2 PFL mirrors. Each mirror has the same


@@ -59,21 +77,31 @@ specified PFL layout.
 .in
 Create a mirrored file with 3 PFL mirrors. Each mirror has the same specified
 PFL layout.
 .in
 Create a mirrored file with 3 PFL mirrors. Each mirror has the same specified
 PFL layout.

-.TP
-.B lfs mirror create -N -c 1 -S 4M -N -c 2 -o 2,3 -N --parent /mnt/lustre/file1
+.LP
+.B lfs mirror create -N -c 1 -S 4M -N -c 2 -o 2,3 -p flash
+.B -N -p none /mnt/lustre/file1
+.in

 Create a mirrored file with 3 plain layout mirrors. The first mirror has a
 single stripe and 4MB stripe size. The second mirror has two stripes and locates
 Create a mirrored file with 3 plain layout mirrors. The first mirror has a
 single stripe and 4MB stripe size. The second mirror has two stripes and locates

-on OSTs with indices 2 and 3. It also has 4MB stripe size inherited from the
-first mirror. The third mirror has default striping pattern inherited from
-parent directory.
+on OSTs with indices 2 and 3 allocated from the \fBflash\fR OST pool.
+It also has 4MB stripe size inherited from the first mirror.
+The third mirror has two stripes and 4MB stripe size inherited from the previous
+mirror, and also has inherited OST \fIpool_name\fR from parent directory.

 .LP
 .LP

-.B lfs mirror create -N2 -E 4M -c 2 --pool flash -E eof -c 4 -N3 -E 16M -c 4 -S
-.B 16M --pool archive -E eof -c -1 /mnt/lustre/file1
+.B lfs mirror create -N2 -E 4M -c 2 --pool flash --flags prefer -E eof -c 4
+.B -N3 -E 16M -c 4 -S 16M --pool archive --comp-flags=prefer -E eof -c -1
+.B /mnt/lustre/file1

 .in
 Create a mirrored file with 5 PFL mirrors. The first and second mirrors have the
 same PFL layout, and both of the components are allocated from the \fBflash\fR
 .in
 Create a mirrored file with 5 PFL mirrors. The first and second mirrors have the
 same PFL layout, and both of the components are allocated from the \fBflash\fR

-OST pool. The last three mirrors have the same PFL layout, and each of these
+OST pool. Also, flag \fBprefer\fR is applied to all the components of the first
+two mirrors, which tells the client to read data from those components whenever
+they are available.
+.br
+The last three mirrors have the same PFL layout, and each of these

 components have a stripe size of 16MB and use OSTs in the \fBarchive\fR pool.
 components have a stripe size of 16MB and use OSTs in the \fBarchive\fR pool.

+However, the flag \fBprefer\fR is only applied to the first component of each
+mirror.

 .SH AUTHOR
 The \fBlfs mirror create\fR command is part of the Lustre filesystem.
 .SH SEE ALSO
 .SH AUTHOR
 The \fBlfs mirror create\fR command is part of the Lustre filesystem.
 .SH SEE ALSO