1 .TH lfs_migrate 1 "Dec 19, 2017" Lustre "utilities"
4 \- migrate files between Lustre OSTs
9 .RB [ --no-rsync | --rsync ]
16 .RB [ -A [ -C \fI<cap> \fR] [ -M \fI<min_free> \fR] [ -X \fI<max_free> \fR]]
17 .RB [ --stripe-count|-c \fI<stripe_count> \fR]
18 .RB [ --stripe-size|-S \fI<stripe_size> \fR]
20 .RI [ FILE | DIR ] ...
24 is a tool to assist migration of files between Lustre OSTs, possibly also
25 restriping the files as it goes. It copies each specified file to a new file,
26 verifies the file contents have not changed, and then replaces the original
27 filename with the new file (either atomically via
29 on Lustre 2.5 and later, or
31 on older versions of Lustre). This allows balancing space usage between OSTs,
32 moving files off OSTs that are starting to show hardware problems but are still
33 functional, or OSTs that will be removed from the filesystem.
35 Files to be migrated can be specified as command-line arguments. If a
36 directory is specified on the command-line then all files within that
37 directory are migrated. If no files are specified on the command-line,
38 then a list of files is read from the standard input, making
42 to locate files on specific OSTs and/or matching other file attributes,
43 or any other tools that generate a list of files.
45 Any options and arguments not explicitly recognized by
47 are passed through to the underlying
53 for a complete list of options.
55 To maintain backward compatibility, the \fI-n \fRoption is used by the
56 script to indicate a dry-run (no modifications made), and is not passed to
58 as the non-block option. To specify non-block, use the long option
61 The current file allocation policies on MDS dictate where the new files
62 are placed, taking into account whether specific OSTs have been disabled
65 (preventing new files from being allocated there), whether
66 some OSTs are overly full (reducing the number of files placed on those
67 OSTs), or if there is a specific default file striping for the target
68 directory (potentially changing the stripe count, stripe size, OST pool,
69 or OST index of a new file).
73 Only print the names of files to be migrated.
76 Do not use direct I/O to copy file contents.
79 Automatically determine the stripe count for the file, using the algorithm
80 count = sqrt(filesize_in_GB) + 1. This option may not be specified at the
81 same time as the \fB-c \fRor \\-R \fRoptions.
83 .B \\--stripe-count|-c \fI<stripe_count>
84 Restripe file using the specified \fIstripe_count\fR. This option may not be
85 specified at the same time as the \fB-A \fRor \fB-R \fRoptions.
88 When \fB-A \fRis set, limit the migrated file to use on each OST at most
89 1/\fIcap \fRof the available space of the smallest OST. If this option is not
90 set, a default value of 100 is used, limiting the object size to 1% of available
94 Display help information.
97 Do not fall back to using rsync if
98 .BR lfs-migrate (1) " fails."
99 Cannot be used at the same time as \fB--rsync\fR.
100 .B \\--min-free|-M \fI<min_free>
101 When \fB-A \fRis set, only consider OSTs with free space greater than the
102 \fImin_free \fRvalue to be available for migration. The value is specified in
103 KB. If this option is not set, a default of 256MB is used.
106 Run quietly (don't print filenames or status).
109 Force rsync to be used instead of
110 .BR lfs-migrate (1) .
111 May not be used at the same time as
115 Restripe file using default directory striping instead of keeping striping.
116 This option may not be specified at the same time as the \fB-A\fR, \fB-c\fR, or
117 \fB-S \fRoptions. (these options are passed through to
119 and are therefore not listed here).
122 Skip file data comparison after migrate. Default is to compare migrated file
123 against original to verify correctness.
126 Show verbose debug messages.
127 .B \\--max-free|-X \fI<max_free>
128 When \fB-A \fRis set, \fImax_free \fRis the maximum amount of free space that
129 can be considered available for the migration of the file on each OST. The
130 value is specified in KB. This option is useful for testing, by simulating
131 OSTs that are nearly full.
134 Answer 'y' to usage warning without prompting (for scripts; use with caution).
136 To rebalance all files within
138 .B \\--stripe-size|-S
140 Restripe file using the specified stripe size. This option may not be
141 specified at the same time as the \fB-R \fRoption.
144 Answer 'y' to usage warning without prompting (for scripts, use with caution).
147 Input file names on stdin are separated by a null character.
149 To rebalance all files within
151 (which are known not to be modified by in-use programs):
153 lfs_migrate /testfs/jobs/2011
155 To migrate files within the
157 filesystem on OST0004 (perhaps because it is much more full than other OSTs),
158 larger than 4GB (because it is more efficient to just migrate large files),
159 and older than two days (to avoid files that are in use, though this is NOT
160 a guarantee the files are not being modified, that is workload specific) after
161 disabling file creation on testfs-OST0004 (this is needed on all MDS nodes):
164 mds# lctl set_param osp.testfs-OST0004*.max_create_count=0
165 client# lfs find /testfs -obd testfs-OST0004 -size +4G -mtime +2d | lfs_migrate -y
166 mds# lctl set_param osp.testfs-OST0004*.max_create_count=20000
169 To use automatic striping, and limit the object size per OST to 5% of current
172 lfs_migrate -A -C 20 /testfs/jobs/2011
174 In versions prior to 2.5,
178 closely integrated with the MDS, and cannot determine whether a file
179 is currently open and/or in-use by other applications or nodes. That makes
182 for use on files that might be modified by other applications, since the
183 migrated file is only a copy of the current file. This will result in the
184 old file becoming an open-unlinked file, and any modifications to that file
190 filesystem package. Added in the 1.8.4 release.