-.TH LFS-MIGRATE 1 2015-12-07 "Lustre" "Lustre Utilities"
+.TH LFS-MIGRATE 1 2021-11-08 "Lustre" "Lustre Utilities"
.SH NAME
lfs migrate \- migrate files or directories between MDTs or OSTs.
.SH SYNOPSIS
.B lfs migrate
.RB [ -h "] [" -v ]
.RI [ SETSTRIPE_OPTIONS " ... ]"
-.RI < file "> ..."
+.IR FILE " ..."
.br
-.B lfs migrate -m \fIstart_mdt_index
+.B lfs migrate -m \fISTART_MDT_INDEX
.RB [ -cHv ]
-.RI < directory >
+.I DIRECTORY
.br
.SH DESCRIPTION
-Migrate OST objects or MDT inodes between MDTs and OSTs respectively.
+Migrate OST objects between OSTs for the specified
+.IR FILE ,
+or recursively migrate
+.I DIRECTORY
+and all inodes/directories therein between MDTs.
+.SH OST MIGRATE OPTIONS
.P
The
.B lfs migrate
.I SETSTRIPE_OPTIONS
listed in
.BR lfs-setstripe (1)
-to specify the layout of the target file. The migrate command differs
-from
+to specify the layout of the target file. The migrate command differs from
.B lfs setstripe
in that
.B lfs migrate
to the new OST(s). In contrast,
.B lfs setstripe
is used for creating new (empty) files with the specified layout.
-.SH OST MIGRATE OPTIONS
For OST object migration, there additional options available:
.TP
.BR -b , --block
for details.
.SH MDT MIGRATE OPTIONS
.TP
-.BR -m , --mdt-index=\fIstart_mdt_index\fR
-Directory will be migrated to MDTs starting with
-.I start_mdt_index
-, or specific MDTs if multiple MDTs are specified in a comma-seperated list.
+.BR -m , --mdt-index=\fIMDT_INDEX [, \fIMDT_INDEX ,...]
+The specified
+.I DIRECTORY
+.B and all subdirectories and inodes
+will be migrated to the MDT with the specified
+.IR MDT_INDEX .
This is useful if new MDTs have been added to a filesystem and existing user or
project directories should be migrated off old MDTs to balance the space usage
and future metadata workload. If
-.I start_mdt_index
-is set to -1, the MDT will be chosen by space and inode usage.
+.I MDT_INDEX
+is -1, the MDT index will be balanced by free space and inodes among
+available MDTs. If multiple
+.I MDT_INDEX
+values are specified in a comma-seperated list, then all
+subdirectories will be
+.B striped
+across all of the specified MDT indices as if an equivalent
+.BI -c N
+option were given.
.TP
.BR -c , --mdt-count=\fICOUNT\fR
-Directory will be migrated to
+All directories and subdirectories in the tree will be striped across
+.I COUNT
+MDTs, always using
+.I MDT_INDEX
+as the primary MDT for the directory. If
+.I MDT_INDEX is
+.B -1
+then
.I COUNT
-MDTs.
+directory stripes will be chosen from MDTs proportional to the amount
+of free inodes and space on each MDT. If multiple
+.I MDT_INDEX
+values are specified in a comma-separated list, then the number of specified
+.I MDT_INDEX
+values must match
+.IR COUNT .
.TP
.BR -H , --mdt-hash=\fIHASH_TYPE\fR
Use
.I HASH_TYPE
-for the new layout.
+for the new directory layout.
.RS 1.2i
.TP
.B all_char (type 1)
during directory restripe.
.RE
.P
+.TP
+.B NOTE
Only the root user can migrate directories. Files that have been archived by
HSM or are currently opened will fail to migrate, user can run the same migrate
command again to finish migration when files are ready. Both inode and
directory entry will be migrated. During migration directory and sub files can
-be accessed like normal ones.
+be accessed like normal ones, but the migration itself cannot be interrupted.
+.TP
+.B NOTE
+It is not currently possible to migrate files with an
+.B mdt
+component (Data-on-MDT, DoM). If it is necessary to migrate such files off
+a particular MDT, they must first be migrated to have a non-DoM file layout
+and then the inodes migrated separately. See
+.B EXAMPLES
+for details on how to migrate DoM files between MDTs.
.TP
-\fIWARNING\fR
-A migrated file or directory will have a new FID, and hence a new inode
+.B WARNING
+Each migrated file or directory will have a new FID, and hence a new inode
number. As a consequence, files archived by Lustre HSM that depend on
the FID as the identifier in the HSM archive cannot currently be migrated.
Having a new inode number may also cause backup tools to consider the
.SH EXAMPLES
.TP
.B $ lfs migrate -c 2 /mnt/lustre/file1
-This migrates the file into a new layout with 2 stripes.
+This migrates the data in
+.B file1
+into a new layout with 2 stripes.
.TP
-.B $ lfs migrate -E 64M -c 1 -E 256M -c 4 -E -1 -c -1 /mnt/lustre/file1
-This migrates the file into a three component composite layout.
+.B $ lfs migrate -E 256M -c 1 -E 16G -c 4 -E eof -c 40 /mnt/lustre/file2
+.br
+This migrates the data in
+.B file2
+into a three component composite layout (number of stripes depends on
+file size).
.TP
-.B $ lfs migrate -m 0,2 ./testremote
-Move the inodes contained in directory ./testremote from their current
-MDT to the MDT with index 0 and 2.
+.B # lfs migrate -m 0,2 testremote
+.br
+Recursively move the subdirectories and inodes contained in directory
+.B remotedir
+from its current MDT to MDT0000 and MDT0002. The
+.B testremote
+directory and all of its subdirectories will be striped across both MDTs.
+.TP
+.B # lfs setstripe -E 256M -c 1 -E 16G -c 4 -E eof -c 40 topdir
+Set a default PFL layout (without any DoM component) on the directory
+.BR topdir ,
+.TP
+.B # lfs find dir -type f -L mdt -0 | xargs -0 lfs migrate --copy topdir
+then find and migrate all regular files that have an
+.B mdt
+component to copy the default layout from the specified
+.BR topdir ,
+.TP
+.B # lfs migrate -m 2 topdir
+.br
+and finally migrate the directory
+.B topdir
+and all files and subdirectories in that tree to MDT0002. This allows
+migrating files with DoM components off an MDT.
.SH AUTHOR
The lfs command is part of the Lustre filesystem.
.SH SEE ALSO
git://git.whamcloud.com / fs / lustre-release.git / blobdiff