реорганизатор файловой системы для XFS (filesystem reorganizer for XFS)
Имя (Name)
xfs_fsr - filesystem reorganizer for XFS
Синопсис (Synopsis)
xfs_fsr [-vdg] [-t seconds] [-p passes] [-f leftoff] [-m mtab]
xfs_fsr [-vdg] [xfsdev | file] ...
xfs_fsr -V
Описание (Description)
xfs_fsr is applicable only to XFS filesystems.
xfs_fsr improves the organization of mounted filesystems. The
reorganization algorithm operates on one file at a time,
compacting or otherwise improving the layout of the file extents
(contiguous blocks of file data).
The following options are accepted by xfs_fsr. The -m, -t, and
-f options have no meaning if any filesystems or files are
specified on the command line.
-m mtab
Use this file for the list of filesystems to reorganize.
The default is to use /etc/mtab.
-t seconds
How long to reorganize. The default is 7200 seconds (2
hours).
-p passes
Number of passes before terminating global re-org. The
default is 10 passes.
-f leftoff
Use this file instead of /var/tmp/.fsrlast to read the
state of where to start and as the file to store the state
of where reorganization left off.
-v Verbose. Print cryptic information about each file being
reorganized.
-d Debug. Print even more cryptic information.
-g Print to syslog (default if stdout not a tty).
-V Prints the version number and exits.
When invoked with no arguments xfs_fsr reorganizes all regular
files in all mounted filesystems. xfs_fsr makes many cycles over
/etc/mtab each time making a single pass over each XFS
filesystem. Each pass goes through and selects files that have
the largest number of extents. It attempts to defragment the top
10% of these files on each pass.
It runs for up to two hours after which it records the filesystem
where it left off, so it can start there the next time. This
information is stored in the file /var/tmp/.fsrlast_xfs. If the
information found here is somehow inconsistent or out of date it
is ignored and reorganization starts at the beginning of the
first filesystem found in /etc/mtab.
xfs_fsr can be called with one or more arguments naming
filesystems (block device name), and files to reorganize. In
this mode xfs_fsr does not read or write /var/tmp/.fsrlast_xfs
nor does it run for a fixed time interval. It makes one pass
through each specified regular file and all regular files in each
specified filesystem. A command line name referring to a
symbolic link (except to a file system device), FIFO, or UNIX
domain socket generates a warning message, but is otherwise
ignored. While traversing the filesystem these types of files
are silently skipped.
Файлы (Files)
/etc/mtab
contains default list of filesystems to reorganize.
/var/tmp/.fsrlast_xfs
records the state where reorganization left off.
Смотри также (See also)
xfs_fsr(8), mkfs.xfs(8), xfs_ncheck(8), xfs(5).
Примечание (Note)
xfs_fsr improves the layout of extents for each file by copying
the entire file to a temporary location and then interchanging
the data extents of the target and temporary files in an atomic
manner. This method requires that enough free disk space be
available to copy any given file and that the space be less
fragmented than the original file. It also requires the owner of
the file to have enough remaining filespace quota to do the copy
on systems running quotas. xfs_fsr generates a warning message
if space is not sufficient to improve the target file.
A temporary file used in improving a file given on the command
line is created in the same parent directory of the target file
and is prefixed by the string '.fsr'. The temporary files used
in improving an entire XFS device are stored in a directory at
the root of the target device and use the same naming scheme.
The temporary files are unlinked upon creation so data will not
be readable by any other process.
xfs_fsr does not operate on files that are currently mapped in
memory. A 'file busy' error can be seen for these files if the
verbose flag (-v) is set.
Files marked as no-defrag will be skipped. The xfs_io(8) chattr
command with the f attribute can be used to set or clear this
flag. Files and directories created in a directory with the
no-defrag flag will inherit the attribute.
An entry in /etc/mtab or the file specified using the -m option
must have the rw option specified for read and write access. If
this option is not present, then xfs_fsr skips the filesystem
described by that line. See the fstab(5) reference page for more
details.
In general we do not foresee the need to run xfs_fsr on system
partitions such as /, /boot and /usr as in general these will not
suffer from fragmentation. There are also issues with
defragmenting files lilo(8) uses to boot your system. It is
recommended that these files should be flagged as no-defrag with
the xfs_io(8) chattr command. Should these files be moved by
xfs_fsr then you must rerun lilo before you reboot or you may
have an unbootable system.
