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FSFREEZE(8)                                     System Administration                                     FSFREEZE(8)



NAME
       fsfreeze - suspend access to a filesystem (Linux Ext3/4, ReiserFS, JFS, XFS)

SYNOPSIS
       fsfreeze --freeze|--unfreeze mountpoint


DESCRIPTION
       fsfreeze suspends and resumes access to an filesystem

       fsfreeze  halts  new  access to the filesystem and creates a stable image on disk.  fsfreeze is intended to be
       used with hardware RAID devices that support the creation of snapshots.

       fsfreeze is unnecessary for device-mapper devices. The device-mapper (and LVM) automatically freezes  filesys‐
       tem on the device when a snapshot creation is requested.  For more details see the dmsetup(8) man page.

       The  mount-point  argument  is  the pathname of the directory where the filesystem is mounted.  The filesystem
       must be mounted to be frozen (see mount(8)).

       Note that access time updates are also suspends if the filesystem is mounted with the traditional atime seman‐
       tics (mount option strictatime, for more details see mount(8)).


OPTIONS
       -h, --help
              Print help and exit.

       -f, --freeze
              This  option  requests  the  specified  a filesystem to be frozen from new modifications.  When this is
              selected, all ongoing transactions in the filesystem are allowed to complete, new  write  system  calls
              are  halted,  other calls which modify the filesystem are halted, and all dirty data, metadata, and log
              information are written to disk.  Any process attempting to write to the frozen filesystem  will  block
              waiting for the filesystem to be unfrozen.

              Note  that  even after freezing, the on-disk filesystem can contain information on files that are still
              in the process of unlinking.  These files will not be unlinked until the filesystem is  unfrozen  or  a
              clean mount of the snapshot is complete.

       -u, --unfreeze
              This option is used to un-freeze the filesystem and allow operations to continue.  Any filesystem modi‐
              fications that were blocked by the freeze are unblocked and allowed to complete.

       -V, --version
              Show version number and exit.

AUTHOR
       Written by Hajime Taira.

NOTES
       This man page based on xfs_freeze.  One of -f or -u must be supplied to fsfreeze.

SEE ALSO
       mount(8)

AVAILABILITY
       The  fsfreeze  command  is  part  of  the  util-linux   package   and   is   available   from   ftp://ftp.ker‐