mdmon: remove switch-root functionality.

[thirdparty/mdadm.git] / mdmon.8

diff --git a/mdmon.8 b/mdmon.8
index 9be03271430ea31ad85b1902d68c059a6ef37585..2720b45257bae68e3c4601e48dd7c2d3c748f995 100644 (file)
--- a/mdmon.8
+++ b/mdmon.8
@@ -5,7 +5,7 @@ mdmon \- monitor MD external metadata arrays
 
 .SH SYNOPSIS
 
-.BI mdmon " CONTAINER [NEWROOT | PID]"
+.BI mdmon " [--all] [--takeover] CONTAINER"
 
 .SH OVERVIEW
 The 2.6.27 kernel brings the ability to support external metadata arrays.
@@ -128,66 +128,35 @@ device>/<member index>" if the array is to remain readonly.
 CONTAINER
 The
 .B container
-device to monitor.  It can be a full path like /dev/md/container, a simple md
-device name like md127, or
-.I \-\-all
- which tells
-.I mdmon
-to scan for containers and launch an
-.I mdmon
-instance for each one found.
+device to monitor.  It can be a full path like /dev/md/container, or a
+simple md device name like md127.
 .TP
-[NEWROOT]
-In order to support an external metadata raid array as the rootfs
-.I mdmon
-needs to be started in the initramfs environment.  Once the initramfs
-environment mounts the final rootfs
-.I mdmon
-needs to be restarted in the new namespace.  When NEWROOT is specified
-.I mdmon
-will terminate any
-.I mdmon
-instances that are running in the current namespace,
-.IR chroot (2)
-to NEWROOT, and continue monitoring the container.
-
-Alternately the new
-.I mdmon
-can be started after the new root has been installed with
-.I pivotroot
-by passing
-.B /
-as the NEWROOT.  For
-.I mdmon
-to be able to find and kill the old
-.I mdmon
-there must be some part of the filesystem that persists from before
-the
-.I pivotroot
-to afterwards.  This can be
-.B /var/run/mdadm
-or some other directory.  The default other directory is
-.B /lib/init/rw/mdadm
-but this can easily be changed when
-.I mdmon
-is compiled.
-If
-.I mdmon
-cannot store the pid file in
-.B /var/run/mdadm
-it will store it in the other directory until
-.B /var/run/mdadm
-becomes available, or until it is killed.
+.B \-\-takeover
+This instructs
+.I mdmon
+to replace any active
+.I mdmon
+which is currently monitoring the array.  This is primarily used late
+in the boot process to replace any
+.I mdmon
+which was started from an
+.B initramfs
+before the root filesystem was mounted.  This avoids holding a
+reference on that
+.B initramfs
+indefinitely and ensures that the
+.I pid
+and
+.I sock
+files used to communicate with
+.I mdmon
+are in a standard place.
 .TP
-[PID]
-If the second argument to
-.I mdmon
-does not start with a slash it is assumed to be the pid of a previous
-instance of
-.I mdmon
-to kill.  This is used internally by
-.I mdmon
-to pass the pid across a chroot/exec and should not be used otherwise.
+.B \-\-all
+This tells mdmon to find any active containers and start monitoring
+each of them if appropriate.  This is normally used with
+.B \-\-takeover
+late in the boot sequence.
 
 .PP
 Note that
@@ -200,17 +169,16 @@ RAID arrays.  The only times it is run other that by
 is when the boot scripts need to restart it after mounting the new
 root filesystem.
 
-.SH EXMAPLES
+.SH EXAMPLES
 
-.B "  mdmon --all /"
+.B "  mdmon \-\-all \-\-takeover"
 .br
 Any
 .I mdmon
 which is currently running is killed and a new instance is started.
-This should be run early in the boot sequence after a
-.I pivotroot
-to the final root filesystem, but before that filesystem is remounted
-read-write.
+This should be run late in the boot sequence and particularly after
+.B /var
+is mounted and writable.
 .SH SEE ALSO
 .IR mdadm (8),
 .IR md (4).