+.TP
+.B MDADM_NO_SYSTEMCTL
+If
+.I mdadm
+detects that
+.I systemd
+is in use it will normally request
+.I systemd
+to start various background tasks (particularly
+.IR mdmon )
+rather than forking and running them in the background. This can be
+suppressed by setting
+.BR MDADM_NO_SYSTEMCTL=1 .
+
+.TP
+.B IMSM_NO_PLATFORM
+A key value of IMSM metadata is that it allows interoperability with
+boot ROMs on Intel platforms, and with other major operating systems.
+Consequently,
+.I mdadm
+will only allow an IMSM array to be created or modified if detects
+that it is running on an Intel platform which supports IMSM, and
+supports the particular configuration of IMSM that is being requested
+(some functionality requires newer OROM support).
+
+These checks can be suppressed by setting IMSM_NO_PLATFORM=1 in the
+environment. This can be useful for testing or for disaster
+recovery. You should be aware that interoperability may be
+compromised by setting this value.
+
+.TP
+.B MDADM_GROW_ALLOW_OLD
+If an array is stopped while it is performing a reshape and that
+reshape was making use of a backup file, then when the array is
+re-assembled
+.I mdadm
+will sometimes complain that the backup file is too old. If this
+happens and you are certain it is the right backup file, you can
+over-ride this check by setting
+.B MDADM_GROW_ALLOW_OLD=1
+in the environment.
+
+.TP
+.B MDADM_CONF_AUTO
+Any string given in this variable is added to the start of the
+.B AUTO
+line in the config file, or treated as the whole
+.B AUTO
+line if none is given. It can be used to disable certain metadata
+types when
+.I mdadm
+is called from a boot script. For example
+.br
+.B " export MDADM_CONF_AUTO='-ddf -imsm'
+.br
+will make sure that
+.I mdadm
+does not automatically assemble any DDF or
+IMSM arrays that are found. This can be useful on systems configured
+to manage such arrays with
+.BR dmraid .
+
+