Ubuntu Manpage: drbdlinks - manages links into a shared DRBD partition

NAME

       drbdlinks - manages links into a shared DRBD partition

SYNOPSIS

       drbdlinks [OPTION]... [start|stop|auto|status|monitor|checklinks]

DESCRIPTION

drbdlinks is a program that will manage creation and removal of symbolic links. It is primarily used
with clusters of machines using either shared storage or the "DRBD" replicated block device.

While the name of the program is "drbdlinks", it can be used in any shared-storage sort of environment
where the shared storage is only mounted on the active node. In cases like NFS where the shared storage
is always mounted on all nodes, drbdlinks is not necessary.

The advantage over creating static symbolic links is that package updates often require that directories
point at real files, so updates can often fail if you do not have the shared storage mounted.

drbdlinks also supports multiple instances of links, in the case of active/active clusters. For example,
if you have MySQL running in one resource group, and Apache running in another, you can use the "-c"
switch to specify a configuration file for each resource group.

A simple configuration file, "/etc/drbdlinks.conf", specifies the links. This can be used to manage
links for /etc/httpd, /var/lib/pgsql, and other system directories that need to appear as if they are
local to the system when running applications after a drbd shared partition has been mounted.

When run with "start" as the mode, drbdlinks will rename the existing files/directories, and then make
symbolic links into the DRBD partition. "stop" does the reverse.

Mode "checklinks" will report any links that do not exist in the destination area. During initial setup
and configuration, this can help check that you have the destination file-system set up with the required
components.

If run with "initialize_shared_storage", destination links specified in the configuration file will be
populated from the source storage. This is useful for initial setup to populate the shared storage.
Preceding paths will be populated if they share the same name from source to destination.

The "monitor" and "status" modes will check the file-system against the configuration file and will
report "running" (monitor mode) or "OK" (status mode) if all links appear to be up. Otherwise they
report "down" or "stopped" (respectively).

By default, the rename appends .drbdlinks to the name, but this can be overridden in the configuration
file.

The "list" mode just show the list of links, with each line showing the link, destination, and a 0/1 flag
for bindMount status. This may be useful for user scripts without having to parse the configuration.

An init script is included which runs "stop" before heartbeat starts, and after heartbeat stops. This is
done to try to ensure that when the shared partition isn't mounted, the links are in their normal state.

OPTIONS

       drbdlinks has several options, using either short or long variants.

       -h, --help
              Print a short help message describing the available options and exit.

       -c, --config-file=CONFIGFILE
              Specify  an  alternate  config  file.   The default config file is /etc/drbdlinks.conf.  Alternate
              config files should have a "drbdlinks-" prefix, e.g. "drbdlinks-httpd.conf".

       -s, --suffix=SUFFIX
              Name to append to the local  file-system  name  when  the  link  is  in  place.   The  default  is
              "drbdlinks", which would result in a renamed file like "/etc/httpd.drbdlinks".

       -v, --verbose
              Increase verbosity level by 1 for every occurrence of this option.

EXAMPLES

       Here are a few examples of how drbdlinks can be used.

       The most straight-forward, and default, method for starting drbdlinks:

              drbdlinks start

       To  use  a  suffix  different  from the default when linking to a file or directory, the -s option can be
       used, specifying the desired string:

              drbdlinks -s orig start

       would rename the file-system name to "name.orig".

       Increase the verbosity to assist in debugging:

              drbdlinks -v -v start

       Use an alternate configuration file, possibly from with a DRBD mounted file-system:

              drbdlinks -c /shared1/drbdlinks-httpd.conf start

       This would use the specified configuration file, found on our DRBD  device  mounted  on  /shared1.   This
       would  allow  us to easily keep drbdlinks configurations tied to a specific set of data on a DRBD disk in
       an active/active sort of HA configuration.

AUTHOR