diff options
Diffstat (limited to 'mdmon.8')
| -rw-r--r-- | mdmon.8 | 98 |
1 files changed, 33 insertions, 65 deletions
@@ -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). |