Ubuntu Manpage: s3qllock - Make trees on an S3QL file system immutable

Provided by: s3ql_3.3.2+dfsg-1ubuntu1_amd64

NAME

       s3qllock - Make trees on an S3QL file system immutable

SYNOPSIS

          s3qllock [options] <directory>

DESCRIPTION

       S3QL  is  a  file  system  for  online  data  storage.  Before  using S3QL, make sure to consult the full
       documentation (rather than just the man  pages  which  only  briefly  document  the  available  userspace
       commands).

       The  s3qllock  command  makes  a  directory tree in an S3QL file system immutable. Immutable trees can no
       longer be changed in any way whatsoever. You can not add new files or directories and you can not  change
       or  delete  existing  files  and  directories. The only way to get rid of an immutable tree is to use the
       s3qlrm command.

       s3qllock can only be called by the user that mounted the file system and (if the file system was  mounted
       with --allow-other or --allow-root) the root user.

RATIONALE

Immutability is a feature designed for backups. Traditionally, backups have been made on external tape
drives. Once a backup was made, the tape drive was removed and locked somewhere in a shelf. This has the
great advantage that the contents of the backup are now permanently fixed. Nothing (short of physical
destruction) can change or delete files in the backup.

In contrast, when backing up into an online storage system like S3QL, all backups are available every
time the file system is mounted. Nothing prevents a file in an old backup from being changed again later
on. In the worst case, this may make your entire backup system worthless. Imagine that your system gets
infected by a nasty virus that simply deletes all files it can find -- if the virus is active while the
backup file system is mounted, the virus will destroy all your old backups as well!

Even if the possibility of a malicious virus or trojan horse is excluded, being able to change a backup
after it has been made is generally not a good idea. A common S3QL use case is to keep the file system
mounted at all times and periodically create backups with rsync -a. This allows every user to recover her
files from a backup without having to call the system administrator. However, this also allows every user
to accidentally change or delete files in one of the old backups.

Making a backup immutable protects you against all these problems. Unless you happen to run into a virus
that was specifically programmed to attack S3QL file systems, backups can be neither deleted nor changed
after they have been made immutable.

OPTIONS

       The s3qllock command accepts the following options:

          --log <target>
                 Destination for log messages. Specify none for standard output or syslog for the system logging
                 daemon.  Anything  else will be interpreted as a file name. Log files will be rotated when they
                 reach 1 MiB, and at most 5 old log files will be kept. Default: None

          --debug-modules <modules>
                 Activate debugging output from specified modules (use commas  to  separate  multiple  modules).
                 Debug messages will be written to the target specified by the --log option.

          --debug
                 Activate  debugging  output from all S3QL modules. Debug messages will be written to the target
                 specified by the --log option.

          --quiet
                 be really quiet

          --version
                 just print program version and exit

EXIT CODES

       s3qllock may terminate with the following exit codes:

       0      Everything went well.

       1      An unexpected error occured. This may indicate a bug in the program.

       2      Invalid command line argument or configuration file key.

COPYRIGHT

       © 2008 Nikolaus Rath <Nikolaus@rath.org>