Viewing: lfs-setstripe.1
.TH LFS-SETSTRIPE 1 2017-08-23 "Lustre" "Lustre Utilities"
.SH NAME
lfs-setstripe \- set striping pattern of a file or directory default
.SH SYNOPSIS
.B lfs setstripe \fR[\fISTRIPE_OPTIONS\fR] \fIDIRECTORY\fR|\fIFILENAME\fR
.br
.B lfs setstripe -E \fICOMP_END\fR [\fISTRIPE_OPTIONS\fR] ... \
\fIDIRECTORY\fR|\fIFILENAME\fR
.br
.B lfs setstripe --comp-add -E \fICOMP_END\fR [\fISTRIPE_OPTIONS\fR] ... \
\fIFILENAME\fR
.br
.B lfs setstripe --comp-del \fR[\fB-I \fICOMP_ID\fR|\
\fB--comp-flags=\fICOMP_FLAGS\fR] \fIFILENAME\fR
.br
.B lfs setstripe --comp-set \fR[\fB-I \fICOMP_ID\fR|\
\fB--comp-flags=\fICOMP_FLAGS\fR] \fIFILENAME\fR
.br
.B lfs setstripe -N\fR[\fIMIRROR_COUNT\fR] \fR[\fISTRIPE_OPTIONS\fR] \fIDIRECTORY\fR|\fIFILENAME\fR
.br
.B lfs setstripe -d \fR\fIDIRECTORY\fR
.br
.B lfs setstripe --yaml=\fR\fIYAML_TEMPLATE_FILE.LYL\fR \fIFILENAME\fR
.br
.B lfs setstripe --copy=\fR\fISOURCE_TEMPLATE_FILE\fR \fIFILENAME\fR
.br
.B lfs setstripe --foreign\fR[\fB=\fR\fIFOREIGN_TYPE\fR] \
\fR[\fB--flags=\fR\fIHEX\fR] \fB--xattr=\fR\fILAYOUT_STRING\fR \fIFILENAME\fR
.SH DESCRIPTION
.nh
.ad l
The
.B lfs setstripe
command is used to create a new
.I FILENAME
in a Lustre filesystem with the specified layout, or to specify the default
layout for new files created in
.IR DIRECTORY ,
or anywhere in the filesystem if
.I DIRECTORY
is the filesystem root and no other layout takes precedence.
.PP
Files with composite layouts allow different
.I STRIPE_OPTIONS
to be specified for non-overlapping extents of the file. Files will
inherit options not explicitly specified on the command line either from
the default layout on the parent directory, or from the filesystem-wide
default. New subdirectories created under root directory will not explicitly
copy the default layout at creation time, but will implicitly inherit the
default layout at runtime. The default layout set on a non-root directory
will be copied to any new subdirectories created within that directory
at the time they are created.
Setstripe can be restricted to privileged users
.RB (with CAP_SYS_RESOURCE ,
see
.BR setcap (8))
by setting the parameter
.BR llite.*.enable_setstripe_gid=0 ,
to an administrator group (e.g.
.BR wheel )
by using its numeric group ID, or
.B -1
to permit all users this functionality (the default).
.TP
.B lfs setstripe \fR[\fISTRIPE_OPTIONS\fR ...] \fIDIRECTORY\fR|\fIFILENAME\fR
Create a new
.I FILENAME
with specified plain layout using the specified
.IR STRIPE_OPTIONS ,
or replace the default file layout on an existing
.IR DIRECTORY .
.TP
.B lfs setstripe -E \fIEND_OFFSET\fR [\fISTRIPE_OPTIONS\fR] ... \
\fIDIRECTORY\fR|\fIFILENAME\fR
.br
Create a new composite
.I FILENAME
with one or more component layouts (where \fIEND_OFFSET\fR marks the end of the
current component), or set or replace the default file layout on an existing
.IR DIRECTORY.
.TP
.B lfs setstripe --component-add -E \fIEND_OFFSET\fR [\fISTRIPE_OPTIONS\fR] \
... \fIFILENAME\fR
.br
Add one or more components after the last component of an existing composite
file that does not yet have a component at
.BR eof .
.TP
.B lfs setstripe --comp-del \fR[\fB-I \fICOMP_ID\fR | \
\fB--comp-flags \fICOMP_FLAGS\fR] \fIFILENAME\fR
Remove the component(s) specified by component ID or flags from
.IR FILENAME .
.TP
.B lfs setstripe --comp-set \fR[\fB-I \fICOMP_ID\fR | \
\fB--comp-flags \fICOMP_FLAGS\fR] \fIFILENAME\fR
Set or clear
.I COMP_FLAGS
on the specified component. This command can be only
be applied to mirrored files.
.TP
.B lfs setstripe -N \fR[\fIMIRROR_COUNT\fR] \fR[\fICOMPONENT_OPTIONS\fR] \fIDIRECTORY\fR|\fIFILENAME\fR
Create a new
.I FILENAME
with the specified number of mirrors and other specified layout options, or
set or replace the default file layout on an existing
.IR DIRECTORY .
.TP
.B lfs setstripe -d \fR\fIDIRECTORY\fR
.br
Delete the default layout on the specified directory. It is not necessary
to delete the default layout on a directory before replacing it, only if
the directory should revert from a directory-specific default layout
to using the global filesystem default layout stored on the root directory.
.TP
.B lfs setstripe --yaml=\fR\fIYAML_TEMPLATE_FILE.LYL\fR \fIFILENAME\fR
.br
Create a new
.I FILENAME
using the Lustre YAML Layout template
.IR YAML_TEMPLATE_FILE.LYL ,
created from
.I EXISTING_FILE
via:
.br
.B lfs getstripe --yaml \fR\fIEXISTING_FILE\fR > \fIYAML_TEMPLATE_FILE.LYL\fR
.br
.I YAML_TEMPLATE_FILE.LYL
is a plain-text file that may be saved and/or modified after creation.
This allows complex file layouts to be created once and re-used later.
.TP
.B lfs setstripe --copy=\fR\fISOURCE_TEMPLATE_FILE\fR \fIFILENAME\fR
.br
Create a new
.I file
using the same layout as an existing
.IR SOURCE_TEMPLATE_FILE .
This is similar to the
.B --yaml
option but avoids the need for the intermediate
.B .lyl
file.
.TP
.B lfs setstripe --foreign[=\fR\fIFOREIGN_TYPE\fR\fB] \
[--flags=\fR\fIHEX\fR\fB] --xattr=\fR\fILAYOUT_STRING\fR \fIFILENAME\fR
.br
Create a new
.I FILENAME
with a foreign/non-lustre layout of type
.I FOREIGN_TYPE \fR(\fBnone\fR, \fBdaos\fR, ...)
with flags
.I HEX
and a free-format layout value of
.I LAYOUT_STRING.
.SH STRIPE_OPTIONS
The various OST stripe related options are listed and explained below:
.TP
.B -c\fR, \fB--stripe-count \fR\fISTRIPE_COUNT\fR
The number of OSTs to stripe a file over. \fB0 \fRmeans to use the
filesystem-wide default stripe count (default 1), and \fB-1 \fRmeans to stripe
over all available OSTs.
.TP
.B -C\fR, \fB--overstripe-count \fR\fISTRIPE_COUNT\fR
The number of stripes to create, creating > 1 stripe per OST if count exceeds
the number of OSTs in the file system. \fB0 \fRmeans to use the filesystem-wide
default stripe count (default 1), and \fB range -1 to -32\fRmeans to stripe
over all available OSTs in multiple of OST count. For example, \fB-1\fR means
one stripe per OST, -2 means two stripes per OST, and so on.
.TP
.B -S\fR, \fB--stripe-size \fR\fISTRIPE_SIZE\fR
The number of bytes to store on each OST before moving to the next OST. A
stripe size of
.B 0
means the file should use the filesystem-wide default stripe size
(default 4MiB). An optional suffix can be used to specify the units in
.BR K ibi-,
.BR M "ebi-, or"
.BR G ibibytes.
The
.I STRIPE_SIZE
must be a multiple of 64KiB. Values below 4096 are assumed to be in KiB units.
.TP
.B -i\fR, \fB--stripe-index \fR\fISTART_OST_IDX\fR
The OST index (starting at 0) on which to start striping for this file. A
.I START_OST_IDX
of
.B -1
allows the MDS to choose the starting index and it is strongly recommended, as
this allows space and load balancing to be done by the MDS as needed.
.TP
.BR -L ", " --layout " \fILAYOUT_TYPE"
The type of layout for that component, which can be one of:
.RS
.B raid0\fR - stripe the file data across
\fISTRIPE_COUNT\fR OST objects in units of
\fISTRIPE_SIZE\fR chunks. This is the default layout if not specified.
.RE
.RS
.B mdt\fR - place the first component of the file data on the MDT for faster
access where the inode is located. This can be used for small files, and with
composite file layouts. The
.B mdt
type may only be used for first component of a file. The
.IR STRIPE_SIZE
of the MDT component is always equal to the component size. There is also a
per-MDT tunable parameter
.IR lod.dom_stripesize
that limits the maximum size of a DoM stripe. It can be changed on the MDS via
.B lctl set_param lod.*.dom_stripesize=\fR\fISTRIPE_SIZE\fR ,
where
.I STRIPE_SIZE
must be a multiple of 64KiB in size,
see also
.BR lctl (8)
for details.
.RE
.TP
.B -o\fR, \fB--ost \fR\fIOST_IDX\fR
Used to specify the exact stripe layout on the file system. \fIOST_IDX\fR
is a list of OSTs referenced by their indices, which are specified in decimal
or hex form and can be obtained using the
.B lfs osts
command. The list format consists of individual OST indices and index ranges
separated by commas, e.g. 1,2-4,7. The
.B -o
option may be specified multiple times to stripe across the union of all listed
OSTs. If the
.B -c
option is combined with
.B -o
the
.I STRIPE_COUNT
must agree with the number of OSTs in
.IR OST_IDX .
If the
.B -i
option is combined with
.B -o
the
.I START_OST_IDX
must be in the OST list, and it will be used as the index on which to start
striping the file. Otherwise the striping will occur in the order specified in
.IR OST_IDX .
.TP
.B -p\fR, \fB--pool \fR\fIPOOL_NAME\fR
Allocate objects from the predefined OST pool
.I POOL_NAME
for the layout of this file or component. The
.IR STRIPE_COUNT ,
.IR STRIPE_SIZE ,
and
.I START_OST_IDX
can be used to select a subset of the OSTs within the pool; the
.I START_OST_IDX
must be part of the pool or an error will be returned.
It is possible to specify a different pool for each component of a file. If
no pool is specified, it will be inherited from the previous component (for
later components of a composite layout) or the parent or root directory (for
plain
.B raid0
layouts, or the first component of a composite file).
Use
.BR pool_name=ignore
to force a component without a pool set (no inheritance from last component,
root or parent).
Use
.BR pool_name=''
or
.BR pool_name=inherit
(since Lustre 2.15) to force a component to inherit the pool from the parent
or root directory instead of the previous component.
.TP
.B --foreign \fR[\fIFOREIGN_TYPE\fR]
file layout is non-lustre/free-format and of type
.IR FOREIGN_TYPE
, if specified (see also
.IR --xattr
and
.IR --flags
options).
Current known types are
.BR none
and
.BR symlink
, default is
.BR none
.
.B -x\fR, \fB--xattr \fR\fILAYOUT_STRING\fR
Mandatory non-lustre/free-format layout/LOV EA content for
.I foreign
file.
.TP
.B -F\fR, \fB--flags \fR\fIHEX\fR
Optional bitmap of flags for foreign type.
.SH COMPONENT_OPTIONS
The various component related options are listed and explained below. The
.B --component-*
options can be shortened to
.B --comp-*
if desired.
.TP
.B -E\fR, \fB--component-end \fR\fIEND_OFFSET\fR
Add a new component to a file using the
.I STRIPE_OPTIONS
following the
.B -E
argument. These options apply to the component ending at offset
.I END_OFFSET
in bytes, or by using a suffix (KMGTP) to specify base-two units,
such as 256M for 2^28 bytes. An offset of
.B -1
or
.B eof
means the following options extend to the end of the file. The first
component starts at offset 0, and each subsequent component starts at
the end of the previous component, so they must be specified in increasing
file offset order, and must be a multiple of 64KiB to align with the
minimum
.I STRIPE_SIZE
value. Values below 4096 are assumed to be in KiB units.
.PP
.RS
The first component specified will inherit default parameters from the
parent directory or the root directory like a plain layout, as specified
above. Later components will inherit the default layout parameters from
the previous component. Multiple
.B -E
options are used to separate the
.I STRIPE_OPTIONS
parameters for different regions of the file.
.RE
.PP
.RS
If a file does not have a component extending to
.B eof
it will generate an error when trying to write beyond the last component
.IR end .
This can be useful to limit the size of a file to the end of the last
specified component, or use
.B --component-add
to add more components to the end of the file.
.RE
.TP
.B -z, --extension-size, --ext-size\fR \fIEXT_SIZE\fR
This option modifies the \fB-E\fR option, components which have this
option specified are created as pairs of components, extendable and
extension ones.
.PP
.RS
The extendable component starts at offset 0 if this is the first
component of the file. In this case it ends at offset \fIEXT_SIZE\fR and
it gets the flag \fBinit\fR (initialized). The extendable component starts
at the end of the previous component if this is not the first component of
the file. In this case it ends at the same offset (0-length component).
.PP
The extension component covers the rest of the specified region up to
the \fIEND_OFFSET\fR specified by \fB-E\fR option and gets
the flag \fBextension\fR.
This component covers the space reserved for the extendable component but
not used immediately, the later extension of the extendable component is done
by \fIEXT_SIZE\fR each time until the extension component is used up. This is
used to control the space on OSTs the stripe is located on, in case one of
them is low on space, the remaining extension component region is added to the
next component.
.RE
.TP
.B --ec\fR, \fB--ec-stripe-count \fR\fIDATA_STRIPES\fB+\fIPARITY_STRIPES\fR
Enable Erasure Coding (EC) for the file or directory layout by specifying
the number of
.I DATA_STRIPES
per RAID Set and
.I PARITY_STRIPES
per RAID Set in the format
.IB DATA+PARITY
or
.IB DATA:PARITY.
For example,
.B --ec 8+2
specifies RAID Sets with 8 data stripes and 2 parity stripes each,
providing fault tolerance for up to 2 OST failures per RAID Set.
.PP
.RS
When \fB--ec\fR is specified, a parity mirror is automatically created
that matches the structure of the data mirror using Lustre's File Level
Replication (FLR) mechanism. The parity mirror contains the erasure coding
information needed to reconstruct data in case of OST failures.
.PP
The current EC implementation is "read-only" or "offline" erasure coding.
Any write operation to the file causes the parity mirror to become stale.
While stale, the parity information cannot be used for data reconstruction.
The parity mirror must be resynchronized using the
.BR lfs-mirror-resync (1)
command to bring it back into sync with the data mirror. Once resynchronized,
the parity mirror provides protection for read operations, allowing data
recovery in case of OST failures. This behavior is identical to how
non-parity Lustre mirrors work. See
.BR lfs-mirror-create (1)
and
.BR lfs-mirror-resync (1)
for more information on mirror operations.
.PP
For data components with
.I STRIPE_COUNT
greater than
.IR DATA_STRIPES ,
the data component's stripes are divided into one or more independent RAID
sets, each containing at most
.I DATA_STRIPES
data stripes, each with
.I PARITY_STRIPES
parity stripes. Each RAID Set is an independent protection domain. For example,
a 16-stripe RAID0 data component with \fB--ec 8+2\fR is divided into 2 RAID
Sets of 8+2 (requiring 4 total parity stripes in two independent domains).
A 15-stripe data component with \fB--ec 8+2\fR is divided into one 8+2 RAID
set and one 7+2 RAID Set.
.PP
The
.I DATA_STRIPES
value must be at least 2, and
.I PARITY_STRIPES
must be at least 1 and less than or equal to
.I DATA_STRIPES.
The supported limits are 32 data stripes and 4 parity stripes.
.PP
For 1-stripe components the EC mirror will be created with only 1
parity stripe (ie. only single device redundancy). If 2 (or more)
device redundancy is required for all components, then files should be
created with
.I STRIPE_COUNT=2
(or more) data stripes.
.PP
.B EC Option Inheritance and Order Independence
.PP
The \fB--ec\fR option can appear anywhere in the command line and applies
to all components within the same mirror to ensure the file data can be
recovered even when
.I PARITY_STRIPES
OSTs used by the file have failed. When a single \fB--ec\fR option
is specified, it applies to all components in the parity mirror. When
multiple \fB--ec\fR options are used, each one inherits to subsequent
components until it is replaced by another \fB--ec\fR option. The first
\fB--ec\fR option applies to any components earlier in the command.
.PP
The \fB--ec\fR option is per-mirror and only applies within a single mirror
definition (specified by \fB-N\fR). Different mirrors can have different
EC configurations or no EC at all.
.RE
.TP
.B --ec-expert
Equivalent to \fB--ec\fR but allows EC stripe counts that exceed the
supported limits of 32 data stripes or 4 parity stripes. This option
is intended for expert users who understand the performance and
reliability implications, or for testing purposes.
.PP
.RS
The maximum allowed values are 255 for \fIDATA\fR and 15 for \fIPARITY\fR.
.RE
.TP
.B --component-add
Add components to the end an existing composite file. It is not possible
to add components incrementally to the default directory layout, since the
entire default layout can be replaced with a single
.B lfs setstripe
command. Adding components to mirrored files is not currently allowed.
.TP
.B --component-del
Delete specified the components from an existing file using either the
.BR --component-id | -I
or
.BR --component-flags .
Deletion must start with the last component. The ID specified by the
.B -I
option is the numerical unique ID of the component, it can be obtained using
the
.B lfs getstripe -I
command. It is not possible to delete components from a default directory
layout, since the entire default layout can be replaced with a single
.B lfs setstripe
call.
The \fB--component-flags\fR option is used to specify certain type of
components. The only allowed component flag for deleting a component is
.B ^init
to indicate an uninstantiated component. Deleting a single component from
mirrored files is not currently allowed, see the
.BR lfs-mirror-split (1)
command.
.TP
.B --component-flags \fR\fICOMP_FLAGS\fR
Find, set, or clear
.B flags
on a specific component. Allowed
.I flags
are:
.RS
.B * init\fR - component is initialized (has allocated objects). Used with
.B --component-del --component-flags ^init
to find uninitialized components.
.RE
.RS
.B * prefer\fR - component preferred for read/write in a mirrored file
.RE
.RS
.B * prefrd\fR - component preferred for read in a mirrored file
.RE
.RS
.B * prefwr\fR - component preferred for write in a mirrored file
.RE
.RS
.B * stale\fR - component has outdated data in a mirrored file. This flag is
not allowed to be set on a component of the last non-stale mirror.
Once a component is marked
.BR stale ,
it isn't permitted to clear this flag directly. \fBlfs-mirror-resync\fR(1)
is required to clear the flag.
.RE
.RS
.B * nosync\fR - mirror components will not be resynched by default when the
.BR lfs-mirror-resync (1)
command is run. This option is useful to freeze a file mirror as an old
version or snapshot of the file.
.RE
.RS
A leading '^' before \fIflags\fR clears the flags, or finds components not
matching the flags. Multiple flags can be separated by comma(s).
.RE
.TP
.B -I\fR, \fB--component-id \fR\fICOMP_ID\fR
The numerical unique component ID to identify a component to be modified.
.TP
.BR -N, \fB--mirror-count \fR[\fIMIRROR_COUNT\fR]
Create a file with
.I MIRROR_COUNT
identical replicas on the file or directory. The
.I MIRROR_COUNT
argument is optional and defaults to 1 if it's not specified; if specified,
it must follow the
.B -N
option without a space. The maximum possible value for the mirror count is 16.
.br
The \fISTRIPE_OPTIONS\fR specify the specific layout for the mirror. It
can be a plain layout with specific striping pattern or a composite layout.
If not specified, the stripe options are inherited from the previous
component. If there is no previous component, the
.I STRIPE_COUNT
and
.I STRIPE_SIZE
options are inherited from filesystem-wide default values, and OST
.I POOL_NAME
will be inherited from the parent directory.
.br
Multiple
.B -N
options may be specified, each with its own
.I STRIPE_OPTIONS
if there is a reason to have different layouts for the replicas, such as
flash pools and archive pools (see
.BR lfs-mirror-create (1)
for full details).
.br
.B NOTE
that in the current client implementation, only
.B one
replica will be written by client nodes, and the other replicas need to
be resynched using the
.B lfs mirror resync
command, or an external resync agent.
.SH EXAMPLES
.TP
.B lfs setstripe -S 128K -c 2 /mnt/lustre/file1
This creates a file striped on two OSTs with 128KiB on each stripe.
.TP
.B lfs setstripe -d /mnt/lustre/dir
This deletes a default stripe pattern on dir. New files created in that
directory will use the filesystem global default instead.
.TP
.B lfs setstripe -N2 -E 1M -E eof -c -1 /mnt/lustre/dir1
This sets a default mirror layout on a directory with 2 PFL mirrors. Each mirror
has the same specified PFL layout.
.TP
.B lfs setstripe -N -E 1M -L mdt -E eof --component-flags=prefer -p flash \
-N -E 1G -c 1 -p disk -E eof -c -1 /mnt/lustre/file1
This creates a mirrored file with 2 replicas. The first replica is using the
MDT for files smaller than 1MB, and the remainder of the file is on the
.B flash
OST pool with filesystem-wide default values. The second replica is on the
.B disk
OST pool, with 1 stripe for the first 1GB of the file, and striped across
all OSTs in the
.B disk pool for the remainder of the file. Clients will
.B prefer
the first (flash) replica for both reads and writes.
.TP
.B lfs setstripe -E 4M -c 1 -E 64M -c 4 -E -1 -c -1 /mnt/lustre/file1
This creates a file with composite layout, the component has 1 stripe and
covers [0, 4MiB), the second component has 4 stripes and covers [4MiB, 64MiB),
the last component stripes over all available OSTs and covers [64MiB, EOF).
.TP
.B lfs setstripe -E -1 -z 64M /mnt/lustre/file1
This creates a file with a composite layout, the component one covers [0, 64MiB)
and the second component the rest [64MiB, EOF) originally. Once written beyond
64MiB the component one is extended to [0, 128MiB), once written beyond 128MiB
it is extended to [0, 192MiB), etc; the second component is shortened
appropriately.
.PP
.RS
When one of the OSTs of the first component layout is low on space, e.g. while
writing beyond 192MiB, the first component is left as [0, 192MiB), and a new
component is allocated between them, its layout repeats the first component
layout but initialized on different OSTs so that the full OSTs are avoided.
It is allocated and immediately extended to [192MiB, 256MiB), the following
extension component is shortened again.
.RE
.TP
.B lfs setstripe -E 1G -z 64M -E 100G -z 256M -E -1 -z 1G /mnt/lustre/file1
This creates a file with a composite layout, the component one covers [0,
64MiB), the third component covers [1G, 1G), the fifth component covers
[100GiB, 100GiB) originally. The second, fourth and sixth extension components
cover the left space accordingly. The process of writing is similar to above,
but when one of the OSTs of the first component layout is low on space, e.g.
while writing beyond 192MiB in the example above, the first component is left
as [0, 192MiB), the second (extension) component is removed, and its range
spills over to the third and the fourth components - they are moved left to
start at 192MiB instead of 100GiB; the third component is immediately extended
and becomes [192MiB, 448MiB), the fourth (the extension one) component becomes
[448MiB, 100GiB).
.TP
.B lfs setstripe --component-add -E eof -c 4 /mnt/lustre/file1
This add a component which starts at the end of last existing component to
the end of file.
.TP
.B lfs setstripe --component-del -I 1 /mnt/lustre/file1
This deletes the component with ID equal to 1 from an existing file.
.TP
.B lfs setstripe --comp-set -I 1 --comp-flags=^prefer,stale /mnt/lustre/file1
This command will clear the \fBprefer\fR flag and set the \fBstale\fR flag on
.B file1
component ID 1.
.TP
.B lfs setstripe -E 1M -L mdt -E -1 /mnt/lustre/file1
Create
.B file1
with Data-on-MDT layout. The first 1MiB of the file data is placed on the
MDT and rest of file is placed on OST(s) with default striping.
.TP
.B lfs setstripe --yaml=/tmp/layout_yaml /mnt/lustre/file2
This creates
.B file2
with layout stored in the layout template
file
.B layout_yaml
which can be created with the
.B lfs getstripe --yaml
command.
.TP
.B lfs setstripe --foreign=symlink --flags=0xda08 \
--xattr=PUUID:CUUID /mnt/lustre/file1
This creates foreign
.BR file1
of type
.BR symlink
with non-lustre/free-format
.BR PUUID:CUUID
layout/LOV EA and flags
.BR 0xda08
.
.TP
.B lfs setstripe -E -1 -c 8 --ec 8+2 /mnt/lustre/file1
This creates
.B file1
with an Erasure Coding layout using 8 data stripes and 2 parity stripes.
The file will have two mirrors: a data mirror with 8 stripes and a parity
mirror with the erasure coding information. Since the data component has
8 stripes and the EC specification is 8+2, this creates a single RAID Set
with 8 data stripes and 2 parity stripes, providing fault tolerance for
up to 2 OST failures with 25% storage overhead.
.TP
.B lfs setstripe --ec 8+2 -E -1 -c 8 /mnt/lustre/file1a
This is equivalent to the previous example, demonstrating if only a single
\fB--ec\fR option is specified, it applies to all components.
.TP
.B lfs setstripe -E 1G -c 4 --ec 4+2 -E -1 -c 8 --ec 8+2 /mnt/lustre/file2
This creates
.B file2
with a composite EC layout. The first component (0 to 1GiB) uses 4 data
stripes with 2 parity stripes (4+2 EC), and the second component (1GiB to
EOF) uses 8 data stripes with 2 parity stripes (8+2 EC). Each component
has both data and parity mirrors.
.TP
.B lfs setstripe -E 128M --ec 8+2 -E -1 -c 4 /mnt/lustre/file2a
This creates
.B file2a
with a composite EC layout where a single \fB--ec 8+2\fR applies to all
components. Both the first component (0 to 128MiB) and the second component
(128MiB to EOF) will use 8+2 EC, demonstrating that one \fB--ec\fR option
applies to all components in the parity mirror.
.TP
.B lfs setstripe -E 128M --ec 4+2 -E 512M -E -1 --ec 8+2 /mnt/lustre/file2b
This creates
.B file2b
with three components demonstrating multiple \fB--ec\fR options. The first
component (0 to 128MiB) uses 4+2 EC. The second component (128MiB to 512MiB)
also uses 4+2 EC (inherited from the first \fB--ec\fR). The third component
(512MiB to EOF) uses 8+2 EC, as specified by the second \fB--ec\fR option.
.TP
.B lfs setstripe -E -1 -c 16 --ec 8+2 /mnt/lustre/file3
This creates
.B file3
with 16 data stripes divided into 2 independent RAID Sets. Each RAID Set
contains 8 data stripes and 2 parity stripes (8+2), for a total of 4 parity
stripes across both RAID Sets. Each RAID Set can tolerate up to 2 OST
failures independently.
.TP
.B lfs setstripe -E -1 -c 20 --ec 8+2 /mnt/lustre/file3a
This creates
.B file3a
with 20 data stripes; this does not evenly divide into 8+2 RAID Sets. The
stripes are automatically divided into multiple RAID Sets of optimal size:
two 7+2 RAID Sets (14 data stripes, 4 parity stripes) and one 6+2 RAID Set
(6 data stripes, 2 parity stripes). This maintains the requested level of
redundancy while creating RAID Sets which are as close to the requested
dimensions as possible.
.TP
.B lfs setstripe -E -1 -c 256 --ec-expert 64+4 /mnt/lustre/file4
This creates
.B file4
with an EC layout that exceeds the supported limits (32 data stripes,
4 parity stripes). The \fB--ec-expert\fR option allows the use of up to
255 data stripes and up to 15 parity stripes per RAID Set. With 256 data
stripes and 64+4 EC, this creates four 64+4 RAID Sets, for a total of 16
parity stripes. This is intended for advanced users who understand the
performance and reliability implications.
.TP
.B lfs setstripe -N -E 128M -E -1 --ec 8+2 -N -E 256M -E -1 /mnt/lustre/file5
This creates
.B file5
with two mirrors. The first mirror has two components with 8+2 EC applied
to both. The second mirror has two components with no EC (plain RAID0).
This demonstrates that \fB--ec\fR is per-mirror: the \fB--ec 8+2\fR only
applies to the first mirror (between the first and second \fB-N\fR), and
does not affect the second mirror.
.TP
.B lfs setstripe -E -1 -c 8 --ec 8+2 /mnt/lustre/dir1
This sets the default EC layout on
.B dir1
so that new files created in this directory will automatically use an
8+2 EC layout with 8 data stripes and 2 parity stripes.
.SH SEE ALSO
.BR lctl (1),
.BR lfs (1),
.BR lfs-migrate (1),
.BR lfs-mirror-create (1),
.BR lfs-mirror-split (1),
.BR lustre (7)
.BR setcap (8)
