nut/docs/config-notes.txt

Configuration notes
===================

This chapter describe most of the configuration and use aspects of NUT,
including establishing communication with the device and configuring safe
shutdowns when the UPS battery runs out of power.

There are many programs and <<Features,features>> in this
package.  You should check out the <<Overview,NUT Overview>>
and other accompanying documentation to see how it all works.

NOTE: NUT does not currently provide proper graphical configuration tools.
However, there is now support for linkdoc:developer-guide[Augeas,augeas_user],
which will enable the easier creation of configuration tools.
Moreover, linkman:nut-scanner[8] is available to discover supported devices
(USB, SNMP, Eaton XML/HTTP and IPMI) and NUT servers (using Avahi or the
classic connection method).

Details about the configuration files
-------------------------------------

Generalities
~~~~~~~~~~~~

All configuration files within this package are parsed with a common
state machine, which means they all can use a number of extras described here.

First, most of the programs use an uppercase word to declare a
configuration directive.  This may be something like MONITOR, NOTIFYCMD,
or ACCESS.  The case does matter here.  "monitor" won't be recognized.

Next, the parser does not care about whitespace between words.  If you
like to indent things with tabs or spaces, feel free to do it here.

If you need to set a value to something containing spaces, it has to be
contained within "quotes" to keep the parser from splitting up the line.
That is, you want to use something like this:

	SHUTDOWNCMD "/sbin/shutdown -h +0"

Without the quotes, it would only see the first word on the line.

OK, so let's say you really need to embed that kind of quote within your
configuration directive for some reason.  You can do that too.

	NOTIFYCMD "/bin/notifyme -foo -bar \"hi there\" -baz"

In other words, `\` can be used to escape the `"`.

Finally, for the situation where you need to put the `\` character into your
string, you just escape it.

	NOTIFYCMD "/bin/notifyme c:\\dos\\style\\path"

The `\` can actually be used to escape any character, but you only really
need it for `\`, `"`, and `#` as they have special meanings to the parser.

When using file names with space characters, you may end up having tricky
things since you need to write them inside `""` which must be escaped:

	NOTIFYCMD "\"c:\\path with space\\notifyme\" \"c:\\path with space\\name\""

`#` is the comment character.  Anything after an unescaped `#` is ignored.

Something like this...

	identity = my#1ups

will actually turn into `identity = my`, since the `#` stops the
parsing. If you really need to have a `#` in your configuration, then
escape it.

	identity = my\#1ups

Much better.

The `=` character should be used with care too. There should be only one
"simple" `=` character in a line: between the parameter name and its value.
All other `=` characters should be either escaped or within "quotes".

	password = 123=123

is incorrect. You should use:

	password = 123\=123

or:

	password = "123=123"

Line spanning
~~~~~~~~~~~~~

You can put a backslash at the end of the line to join it to the next
one.  This creates one virtual line that is composed of more than one
physical line.

Also, if you leave the `""` quote container open before a newline, it will
keep scanning until it reaches another one.  If you see bizarre behavior
in your configuration files, check for an unintentional instance of
quotes spanning multiple lines.


Basic configuration
-------------------

This chapter describes the base configuration to establish communication with
the device.

This will be sufficient for PDU. But for UPS and SCD, you will also need to
configure <<UPS_shutdown,automatic shutdowns for low battery events>>.

image:images/simple.png[]

On operating systems with service management frameworks (such as Linux
systemd and Solaris/illumos SMF), the life-cycle of driver, data server
and monitoring client daemons is managed respectively by `nut-driver`
(multi-instance service), `nut-server` and `nut-monitor` services.
These are in turn wrapped by an "umbrella" service (or systemd "target")
conveniently called `nut` which allows to easily start or stop all those
of the bundled services, which are enabled on a particular deployment.

[[Driver_configuration]]
Driver configuration
~~~~~~~~~~~~~~~~~~~~

Create one section per UPS in 'ups.conf'

NOTE: The default path for a source installation is `/usr/local/ups/etc`,
while packaged installation will vary.
For example, `/etc/nut` is used on Debian and derivatives,
while `/etc/ups` or `/etc/upsd` is used on RedHat and derivatives.

To find out which driver to use, check the
<<HCL,Hardware Compatibility List>>,
or `data/driver.list(.in)` source file.

Once you have picked a driver, create a section for your UPS in
'ups.conf'.  You must supply values at least for "driver" and "port".

Some drivers may require other flags or settings.  The "desc" value
is optional, but is recommended to provide a better description of
what useful load your UPS is feeding.

A typical device without any extra settings looks like this:

	[mydevice]
		driver = mydriver
		port = /dev/ttyS1
		desc = "Workstation"

[NOTE]
======
USB drivers (such as `usbhid-ups` for non-SHUT mode, `nutdrv_qx` for
non-serial mode, `bcmxcp_usb`, `tripplite_usb`, `blazer_usb`, `riello_usb`
and `richcomm_usb`) are special cases and ignore the 'port' value.

You must still set this value, but it does not matter what you set
it to; a common and good practice is to set 'port' to *auto*, but you
can put whatever you like.

If you only own one USB UPS, the driver will find it automatically.

If you own more than one, refer to the driver's manual page for more
information on matching a specific device.
======

References: linkman:ups.conf[5],
linkman:nutupsdrv[8],
linkman:bcmxcp_usb[8],
linkman:blazer[8],
linkman:nutdrv_qx[8],
linkman:richcomm_usb[8],
linkman:riello_usb[8],
linkman:tripplite_usb[8],
linkman:usbhid-ups[8]


[[Starting_drivers]]
Starting the driver(s)
~~~~~~~~~~~~~~~~~~~~~~

Generally, you can just start the driver(s) for your hardware (all sections
defined in 'ups.conf') using the following command:

	upsdrvctl start

Make sure the driver doesn't report any errors.  It should show a
few details about the hardware and then enter the background.  You
should get back to the command prompt a few seconds later.  For
reference, a successful start of the `usbhid-ups` driver looks like this:

	# upsdrvctl start
	Network UPS Tools - Generic HID driver 0.34 (2.4.1)
	USB communication driver 0.31
	Using subdriver: MGE HID 1.12
	Detected EATON - Ellipse MAX 1100 [ADKK22008]

If the driver doesn't start cleanly, make sure you have picked the
right one for your hardware.  You might need to try other drivers
by changing the "driver=" value in 'ups.conf'.

Be sure to check the driver's man page to see if it needs any extra
settings in 'ups.conf' to detect your hardware.

If it says `can't bind /var/state/ups/...` or similar, then your
state path probably isn't writable by the driver.  Check the
<<StatePath,permissions and mode on that directory>> vs. the
user account your driver starts as.

After making changes, try the <<Ownership, Ownership and permissions>>
step again.

Driver(s) as a service
~~~~~~~~~~~~~~~~~~~~~~

On operating systems with init-scripts managing life-cycle of the operating
environment, the `upsdrvctl` program is also commonly used in those scripts.
It has a few downsides, such as that if the device was not accessible during
OS startup and the driver connection timed out, it would remain not-started
until an administrator (or some other script) "kicks" the driver to retry
startup. Also, startup of the `upsd` data server daemon and its clients
like `upsmon` is delayed until all the NUT drivers complete their startup
(or time out trying).

This can be a big issue on systems which monitor multiple devices, such as
big servers with multiple power sources, or administrative workstations
which monitor a datacenter full of UPSes.

For this reason, NUT starting with version 2.8.0 supports startup of its
drivers as independent instances of a `nut-driver` service under the Linux
systemd and Solaris/illumos SMF service-management frameworks (corresponding
files and scripts may be not pre-installed in packaging for other systems).

Such service instances have their own and independent life-cycle, including
parallel driver start and stop processing, and retries of startup in case of
failure as implemented by the service framework in the OS. The Linux systemd
solution also includes a `nut-driver.target` as a checkpoint that all defined
drivers have indeed started up (as well as being a singular way to enable or
disable startup of drivers).

In both cases, a service named `nut-driver-enumerator` is registered, and
when it is (re-)started it scans the currently defined device sections in
'ups.conf' and the currently defined instances of `nut-driver` service,
and brings them in sync (adding or removing service instances), and if
there were changes -- it restarts the corresponding drivers (via service
instances) as well as the data server which only reads the list of sections
at its startup. This helper service should be triggered whenever your system
(re-)starts the `nut-server` service, so that it runs against an up-to-date
list of NUT driver processes.

A service-oriented solution also allows to consider that different drivers
have different dependencies -- such as that networked drivers should begin
startup after IP addresses have been assigned, while directly-connected
devices might need nothing beside a mounted filesystem (or an activated
USB stack service or device rule, in case of Linux). Likewise, systems
administrators can define further local dependencies between services and
their instances as needed on particular deployments.

This solution also adds the `upsdrvsvcctl` script to manage NUT drivers as
system service instances, whose CLI mimics that of `upsdrvctl` program.
One addition is the `resync` argument to trigger `nut-driver-enumerator`,
another is a `list` argument to display current mappings of service
instances to NUT driver sections. Also, original tool's arguments such
as the `-u` (user to run the driver as) or `-D` (debug of the driver)
do not make sense in the service context -- the accounts to use and
other arguments to the driver process are part of service setup (and
an administrator can manage it there).

Note that while this solution tries to register service instances with same
names as NUT configuration sections for the devices, this can not always be
possible due to constraints such as syntax supported by a particular service
management framework. In this case, the enumerator falls back to MD5 hashes
of such section names, and the `upsdrvsvcctl` script supports this to map
the user-friendly NUT configuration section names to actual service names
that it would manage.

References: man pages: linkman:nutupsdrv[8], linkman:upsdrvctl[8],
linkman:upsdrvsvcctl[8]


Data server configuration (upsd)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Configure `upsd`, which serves data from the drivers to the clients.

First, edit 'upsd.conf' to allow access to your client systems. By
default, `upsd` will only listen to `localhost` port 3493/tcp. If you want
to connect to it from other machines, you must specify each interface you
want `upsd` to listen on for connections, optionally with a port number.

	LISTEN 127.0.0.1 3493
	LISTEN ::1 3493

NOTE: Refer to the NUT user manual <<NUT_Security,security chapter>> for
information on how to access and secure upsd clients connections.

Next, create 'upsd.users'.  For now, this can be an empty file.
You can come back and add more to it later when it's time to
configure `upsmon` or run one of the management tools.

Do not make either file world-readable, since they both hold
access control data and passwords.  They just need to be readable by
the user you created in the preparation process.

The suggested configuration is to `chown` it to `root`, `chgrp` it to the
group you created, then make it readable by the group.

	chown root:nut upsd.conf upsd.users
	chmod 0640 upsd.conf upsd.users

References: man pages: linkman:upsd.conf[5],
linkman:upsd.users[5],
linkman:upsd[8]

[[Starting_upsd]]
Starting the data server
~~~~~~~~~~~~~~~~~~~~~~~~

Start the network data server:

	upsd

Make sure it is able to connect to the driver(s) on your system.
A successful run looks like this:

	# upsd
	Network UPS Tools upsd 2.4.1
	listening on 127.0.0.1 port 3493
	listening on ::1 port 3493
	Connected to UPS [eaton]: usbhid-ups-eaton

`upsd` prints dots while it waits for the driver to respond.  Your
system may print more or less depending on how many drivers you
have and how fast they are.

NOTE: If `upsd` says that it can't connect to a UPS or that the data
is stale, then your 'ups.conf' is not configured correctly, or you
have a driver that isn't working properly.  You must fix this before
going on to the next step.

NOTE: Normally `upsd` requires that at least one driver section is
defined in the 'ups.conf' file, and refuses to start otherwise.
If you intentionally do not have any driver sections defined (yet)
but still want the data server to run, respond and report zero devices
(e.g. on an automatically managed monitoring deployment), you can enable
the `ALLOW_NO_DEVICE true` option in the 'upsd.conf' file.

On operating systems with service management frameworks, the data server
life-cycle is managed by `nut-server` service.

Reference: man page: linkman:upsd[8]

Check the UPS data
~~~~~~~~~~~~~~~~~~

Status data
^^^^^^^^^^^

Make sure that the UPS is providing good status data.
You can use the `upsc` command-line client for this:

	upsc myupsname@localhost ups.status

You should see just one line in response:

	OL

`OL` means your system is running on line power.  If it says something
else (like `OB` -- on battery, or `LB` -- low battery), your driver was
probably misconfigured during the <<Driver_configuration, Driver configuration>>
step.  If you reconfigure the driver, use `upsdrvctl stop` to stop it, then
start it again as shown in the <<Starting_drivers, Starting driver(s)>> step.

Reference: man page: linkman:upsc[8]


All data
^^^^^^^^

Look at all of the status data which is being monitored.

	upsc myupsname@localhost

What happens now depends on the kind of device and driver you have.
In the list, you should see `ups.status` with the same value you got
above.  A sample run on an UPS (Eaton Ellipse MAX 1100) looks like this:

	battery.charge: 100
	battery.charge.low: 20
	battery.runtime: 2525
	battery.type: PbAc
	device.mfr: EATON
	device.model: Ellipse MAX 1100
	device.serial: ADKK22008
	device.type: ups
	driver.name: usbhid-ups
	driver.parameter.pollfreq: 30
	driver.parameter.pollinterval: 2
	driver.parameter.port: auto
	driver.version: 2.4.1-1988:1990M
	driver.version.data: MGE HID 1.12
	driver.version.internal: 0.34
	input.sensitivity: normal
	input.transfer.boost.low: 185
	input.transfer.high: 285
	input.transfer.low: 165
	input.transfer.trim.high: 265
	input.voltage.extended: no
	outlet.1.desc: PowerShare Outlet 1
	outlet.1.id: 2
	outlet.1.status: on
	outlet.1.switchable: no
	outlet.desc: Main Outlet
	outlet.id: 1
	outlet.switchable: no
	output.frequency.nominal: 50
	output.voltage: 230.0
	output.voltage.nominal: 230
	ups.beeper.status: enabled
	ups.delay.shutdown: 20
	ups.delay.start: 30
	ups.firmware: 5102AH
	ups.load: 0
	ups.mfr: EATON
	ups.model: Ellipse MAX 1100
	ups.power.nominal: 1100
	ups.productid: ffff
	ups.serial: ADKK22008
	ups.status: OL CHRG
	ups.timer.shutdown: -1
	ups.timer.start: -1
	ups.vendorid: 0463

Reference: man page: linkman:upsc[8],
<<nut-names,NUT command and variable naming scheme>>

Startup scripts
~~~~~~~~~~~~~~~

NOTE: This step is not necessary if you installed from packages.

Edit your startup scripts, and make sure `upsdrvctl` and `upsd` are run
every time your system starts. In newer versions of NUT, you may have a
'nut.conf' file which sets the `MODE` variable for bundled init-scripts,
to facilitate enabling of certain features in the specific end-user
deployments.

If you installed from source, check the `scripts` directory for reference
init-scripts, as well as systemd or SMF service methods and manifests.


[[UPS_shutdown]]
Configuring automatic shutdowns for low battery events
------------------------------------------------------

The whole point of UPS software is to bring down the OS cleanly when you
run out of battery power. Everything else is roughly eye candy.

To make sure your system shuts down properly, you will need to perform some
additional configuration and run upsmon. Here are the basics.

[[Shutdown_design]]
Shutdown design
~~~~~~~~~~~~~~~

When your UPS batteries get low, the operating system needs to be brought
down cleanly.  Also, the UPS load should be turned off so that all devices
that are attached to it are forcibly rebooted, and subsequently start in
the predictable order and state suitable for your data center.

Here are the steps that occur when a critical power event happens,
for the simpler case of one UPS device feeding one or several systems:

1. The UPS goes on battery

2. The UPS reaches low battery (a "critical" UPS), that is to say,
   `upsc` displays:
+
   ups.status: OB LB
+
The exact behavior depends on the specific device, and is related to
such settings and readings as:

   - `battery.charge` and `battery.charge.low`
   - `battery.runtime` and `battery.runtime.low`

3. The `upsmon` primary notices the "critical UPS" situation and sets
   "FSD" -- the "forced shutdown" flag to tell all secondary systems
   that it will soon power down the load.
+
[WARNING]
=========
By design, since we require power-cycling the load and don't
want some systems to be powered off while others remain running
if the "wall power" returns at the wrong moment as usual, the "FSD"
flag can not be removed from the data server unless its daemon is
restarted. If we do take the first step in critical mode, then we
intend to go all the way -- shut down all the servers gracefully,
and power down the UPS.

Keep in mind that some UPS devices and corresponding drivers would
latch the "FSD" again even if "wall power" is available, but the
remaining battery charge is below a threshold configured as "safe"
in the device (usually if you manually power on the UPS after a long
power outage). This is by design of respective UPS vendors, since
in such situation they can not guarantee that if a new power outage
happens, their UPS would safely shut down your systems again.
So it is deemed better and safer to stay dark until batteries
become sufficiently charged.
=========
+
(If you have no secondary systems, skip to step 6)

4. `upsmon` secondary systems see "FSD" and:

   - generate a `NOTIFY_SHUTDOWN` event
   - wait `FINALDELAY` seconds -- typically `5`
   - call their `SHUTDOWNCMD`
   - disconnect from `upsd`

5. The `upsmon` primary system waits up to `HOSTSYNC` seconds (typically `15`)
   for the secondary systems to disconnect from `upsd`.  If any are still
   connected after this time, `upsmon` primary stops waiting and proceeds
   with the shutdown process.

6. The `upsmon` primary:

   - generates a `NOTIFY_SHUTDOWN` event
   - waits `FINALDELAY` seconds -- typically `5`
   - creates the `POWERDOWNFLAG` file in its local filesystem --
     usually `/etc/killpower`
   - calls the `SHUTDOWNCMD`

7. On most systems, `init` takes over, kills your processes, syncs and
   unmounts some filesystems, and remounts some read-only.

8. `init` then runs your shutdown script.  This checks for the
   `POWERDOWNFLAG`, finds it, and tells the UPS driver(s) to power off
   the load by sending commands to the connected UPS device(s) they manage.

9. All the systems lose power.

10. Time passes.  The power returns, and the UPS switches back on.

11. All systems reboot and go back to work.

///////////////////////////////////
https://github.com/networkupstools/nut/issues/1370

TODO: Check other docs and code to spell out expected behavior with
multiple UPS devices (when not all of them go critical or even on battery)
and servers with multiple inputs.

Does the `upsmon` primary system power-cycle a "critical" UPS if that
is not the only one feeding it, so it is not shutting down now?
///////////////////////////////////

How you set it up
~~~~~~~~~~~~~~~~~

[[NUT_user_creation]]
NUT user creation
^^^^^^^^^^^^^^^^^

Create a `upsd` user for `upsmon` to use while monitoring this UPS.

Edit 'upsd.users' and create a new section.  The `upsmon` will connect
to `upsd` and use these user name (in brackets) and password to
authenticate (as specified in its configuration via `MONITOR` line).

This example is for defining a user called "monuser":

	[monuser]
		password = mypass
		upsmon primary
		# or upsmon secondary

References: linkman:upsd[8], linkman:upsd.users[5]

Reloading the data server
^^^^^^^^^^^^^^^^^^^^^^^^^

Reload `upsd`.  Depending on your configuration, you may be able to
do this without stopping the `upsd` daemon process:

	upsd -c reload

If that doesn't work (check the syslog), just restart it:

	upsd -c stop
	upsd

For systems with integrated service management (Linux systemd,
illumos/Solaris SMF) their corresponding `reload` or `refresh`
service actions should handle this as well.

NOTE: If you want to make reloading work later, see the entry in the
link:FAQ.html[FAQ] about starting `upsd` as a different user.

Power Off flag file
^^^^^^^^^^^^^^^^^^^

Set the `POWERDOWNFLAG` location for `upsmon`.

In 'upsmon.conf', add a `POWERDOWNFLAG` directive with a filename.
The `upsmon` will create this file when the UPS needs to be powered off
during a power failure when low battery is reached.

We will test for the presence of this file in a later step.

	POWERDOWNFLAG /etc/killpower

References: man pages: linkman:upsmon[8],
linkman:upsmon.conf[5]

Securing upsmon.conf
^^^^^^^^^^^^^^^^^^^^

The recommended setting is to have it owned by `root:nut`, then make it
readable by the group and not by the world.  This file contains passwords
that could be used by an attacker to start a shutdown, so keep it secure.

	chown root:nut upsmon.conf
	chmod 0640 upsmon.conf

This step has been placed early in the process so you secure this file
before adding sensitive data in the next step.


Create a MONITOR directive for upsmon
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Edit 'upsmon.conf' and create a `MONITOR` line with the UPS definition
(<upsname>@<hostname>), username and password from the
<<NUT_user_creation, NUT user creation>> step, and the
"primary" or "secondary" setting.

If this system is the UPS manager (i.e. it's connected to this UPS directly
and can manage it using a suitable NUT driver), its `upsmon` is the primary:

	MONITOR myupsname@mybox 1 monuser mypass primary

If it's just monitoring this UPS over the network, and some other
system is the primary, then this one is a secondary:

	MONITOR myupsname@mybox 1 monuser mypass secondary

The number `1` here is the "power value".  This should always be set
to 1, unless you have a very special (read: expensive) system with
redundant power supplies. In such cases, refer to the User Manual:

- <<BigServers,typical setups for big servers>>,
- <<DataRoom,typical setups for data rooms>>.

Note that the "power value" may also be 0 for a monitoring (administrative)
system which only observes the remote UPS status but is not impacted by its
power events, and so does not shut down when the UPS does.

References: linkman:upsmon[8], linkman:upsmon.conf[5]

Define a SHUTDOWNCMD for upsmon
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Still in 'upsmon.conf', add a directive that tells `upsmon` how to
shut down your system.  This example seems to work on most systems:

	SHUTDOWNCMD "/sbin/shutdown -h +0"

Notice the presence of "quotes" here to keep it together.

If your system has special needs (e.g. system-provided shutdown handler
is ungracefully time constrained), you may want to set this to a script
which does customized local shutdown tasks before calling `init` or
`shutdown` programs to handle the system side of this operation.


Start upsmon
^^^^^^^^^^^^

	upsmon

If it complains about something, then check your configuration.

On operating systems with service management frameworks, the monitoring client
life-cycle is managed by `nut-monitor` service.

Checking upsmon
^^^^^^^^^^^^^^^

Look for messages in the `syslog` to indicate success.
It should look something like this:

	May 29 01:11:27 mybox upsmon[102]: Startup successful
	May 29 01:11:28 mybox upsd[100]: Client monuser@192.168.50.1
	logged into UPS [myupsname]

Any errors seen here are probably due to an error in the config files of either
`upsmon` or `upsd`.  You should fix them before continuing.


Startup scripts
^^^^^^^^^^^^^^^

NOTE: This step is not need if you installed from packages.

Edit your startup scripts, and add a call to `upsmon`.

Make sure `upsmon` starts when your system comes up.
On systems with `upsmon` primary (also running the data server),
do it after `upsdrvctl` and `upsd`, or it will complain about not
being able to contact the server.

You may delete the `POWERDOWNFLAG` in the startup scripts, but it is not
necessary. `upsmon` will clear that file for you when it starts.

NOTE: Init script examples are provide in the 'scripts' directory of
the NUT source tree, and in the various <<_binary_packages,packages>>
that exist.

Shutdown scripts
^^^^^^^^^^^^^^^^

NOTE: This step is not need if you installed from packages.

Edit your shutdown scripts, and add `upsdrvctl shutdown`.

You should configure your system to power down the UPS after the
filesystems are remounted read-only.  Have it look for the presence
of the `POWERDOWNFLAG` (from linkman:upsmon.conf[5]), using this
as an example:

------------------------------------------------------------------------------

	if (/sbin/upsmon -K)
	then
		echo "Killing the power, bye!"
		/sbin/upsdrvctl shutdown

		sleep 120

		# uh oh... the UPS power-off failed
		# you probably want to reboot here so you don't get stuck!
		# *** see also the section on power races in the FAQ! ***
	fi

------------------------------------------------------------------------------

[WARNING]
==============================================================================
- Be careful that `upsdrvctl shutdown` command will probably power off
your machine and others fed by the UPS(es) which it manages.
Don't use it unless your system is ready to be halted by force.
If you run RAID, read the <<_raid_warning,RAID warning>> below!

- Make sure the filesystem(s) containing `upsdrvctl`, `upsmon`,
the `POWERDOWNFLAG` file, 'ups.conf' and your UPS driver(s) are
mounted (possibly in read-only mode) when the system gets to
this point.  Otherwise it won't be able to figure out what to do.

- If for some reason you can not ensure `upsmon` program is executable
at this point, your script can `(test -f /etc/killpower)` in a somewhat
non-portable manner, instead of asking `upsmon -K` for the verdict
according to its current configuration.
==============================================================================


[[Testing_shutdowns]]
Testing shutdowns
^^^^^^^^^^^^^^^^^

UPS equipment varies from manufacturer to manufacturer and even within
model lines.  You should test the <<Shutdown_design,shutdown sequence>>
on your systems before leaving them unattended.  A successful sequence
is one where the OS halts before the battery runs out, and the system
restarts when power returns.

The first step is to see how `upsdrvctl` will behave without actually
turning off the power. To do so, use the `-t` argument:

	upsdrvctl -t shutdown

It will display the sequence without actually calling the drivers.


You can finally test a forced shutdown sequence (FSD) using:

	upsmon -c fsd

This will execute a full shutdown sequence, as presented in
<<Shutdown_design,Shutdown design>>, starting from the 3rd step.

If everything works correctly, the computer will be forcibly powered
off, may remain off for a few seconds to a few minutes (depending on
the driver and UPS type), then will power on again.

If your UPS just sits there and never resets the load, you are vulnerable
to a power race and should add the "reboot after timeout" hack at the very
least.

Also refer to the section on power races in the link:FAQ.html[FAQ].

Using suspend to disk
~~~~~~~~~~~~~~~~~~~~~

Support for suspend to RAM and suspend to disk has been available in
the Linux kernel for a while now. For obvious reasons, suspending to
RAM isn't particularly useful when the UPS battery is getting low,
but suspend to disk may be an interesting concept.

This approach minimizes the amount of disruption which would be caused
by an extended outage.  The UPS goes on battery, then reaches low
battery, and the system takes a snapshot of itself and halts.  Then it
is turned off and waits for the power to return.

Once the power is back, the system reboots, pulls the snapshot back in,
and keeps going from there.  If the user happened to be away when it
happened, they may return and have no idea that their system actually
shut down completely in the middle (although network connections will drop).

In order for this to work, you need to shutdown NUT (UPS driver, `upsd`
server and `upsmon` client) in the `suspend` script and start them again in
the `resume` script.  Don't try to keep them running.  The `upsd` server
will latch the FSD state (so it won't be usable after resuming) and so
will the `upsmon` client.  Some drivers may work after resuming, but many
don't and some UPS devices will require re-initialization, so it's best not
to keep them running either.

After stopping NUT driver, server and client you'll have to send the UPS
the command to shutdown only if the `POWERDOWNFLAG` is present.  Note
that most likely you'll have to allow for a grace period after calling
`upsdrvctl shutdown` since the system will still have to take a
snapshot of itself after that.  Not all drivers and devices support this,
so before going down this road, make sure that the one you're using does.

- see if you can query or configure settings named like `load.off.delay`,
  `ups.delay.shutdown`, `offdelay` and/or `shutdown_delay`

RAID warning
~~~~~~~~~~~~

If you run any sort of RAID equipment, make sure your arrays are
either halted (if possible) or switched to "read-only" mode.
Otherwise you may suffer a long resync once the system comes back up.

The kernel may not ever run its final shutdown procedure, so you must take
care of all array shutdowns in userspace before `upsdrvctl shutdown` runs.

If you use software RAID (md) on Linux, get `mdadm` and try using
`mdadm --readonly` to put your arrays in a safe state. This has to
happen after your shutdown scripts have remounted the filesystems.

On hardware RAID or other kernels, you have to do some detective work. It may
be necessary to contact the vendor or the author of your driver to find out
how to put the array in a state where a power loss won't leave it "dirty".

Our understanding is that most if not all RAID devices on Linux will be fine
unless there are pending writes.  Make sure your filesystems are remounted
read-only and you should be covered.


[[DataRoom]]
Typical setups for enterprise networks and data rooms
-----------------------------------------------------

The split nature of this UPS monitoring software allows a wide variety of
power connections.  This chapter will help you identify how things should
be configured using some general descriptions.

There are two main elements:

1. There's a UPS attached to a communication (serial, USB or network) port
   on this system.
2. This system depends on a UPS for power.

You can play "mix and match" with those two to arrive at these descriptions
for individual hosts:

- A: 1 but not 2
- B: 2 but not 1
- C: 1 and 2

A small to medium sized data room usually has one 'C' and a bunch of 'Bs'.
This means that there's a system (type 'C') hooked to the UPS which depends
on it for power.  There are also some other systems in there (type 'B')
which depend on that same UPS for power, but aren't directly connected to
it communications-wise.

Larger data rooms or those with multiple UPSes may have several "clusters"
of the "single 'C', many 'Bs'" depending on how it's all wired.

Finally, there's a special case.  Type 'A' systems are connected to
an UPS's communication port, but don't depend on it for power.
This usually happens when an UPS is physically close to a box and can
reach the serial port, but the power wiring is such that it doesn't
actually feed that box.

Once you identify a system's type, use this list to decide which of the
programs need to be run for monitoring:

- A: driver and `upsd`
- B: `upsmon` (in secondary mode)
- C: driver, `upsd`, and `upsmon` (in primary mode, as the UPS manager)

image:images/advanced.png[]

To further complicate things, you can have a system that is hooked to
multiple UPSes, but only depends on one for power.  This particular
situation makes it an `A` relative to one UPS, and a `C` relative to the
other.  The software can handle this -- you just have to tell it what to do.

NOTE: NUT can also serve as a data proxy to increase the number of clients,
or share the communication load between several `upsd` instances.

If you are running large server-class systems that have more than one
power feed, see the next section for information on how to handle it
properly.

[[BigServers]]
Typical setups for big servers with UPS redundancy
--------------------------------------------------

By using multiple `MONITOR` statements in 'upsmon.conf', you can configure
an environment where a large machine with redundant power monitors multiple
separate UPSes.

image:images/bigbox.png[]

Example configuration
~~~~~~~~~~~~~~~~~~~~~

For the examples in this section, we will use a server with four power
supplies installed and locally running the full NUT stack, including
`upsmon` in primary mode -- as the UPS manager.

Two UPSes, 'Alpha' and 'Beta', are each driving two of the power supplies
(by adding up, we know about the four power supplies of the current system).
This means that either 'Alpha' *or* 'Beta' can totally shut down and the
server will be able to keep running.

The 'upsmon.conf' configuration which reflects this is the following:

	MONITOR ups-alpha@myhost 2 monuser mypass primary
	MONITOR ups-beta@myhost  2 monuser mypass primary
	MINSUPPLIES 2

With such configuration, `upsmon` on this system will only shut down when
both UPS devices reach a critical (on battery + low battery) condition,
since 'Alpha' and 'Beta' each provide the same power value.

As an added bonus, this means you can move a running server from one UPS
to another (for maintenance purpose for example) without bringing it down
since the minimum sufficient power will be provided at all times.

The `MINSUPPLIES` line tells `upsmon` that we need at least 2 power supplies
to be receiving power from a good UPS (on line or on battery, just not
on battery *and* low battery).

NOTE: We could have used a 'Power Value' of `1` for both UPS, and have
`MINSUPPLIES` set to `1` too. These values are purely arbitrary, so
you are free to use your own rules. Here, we have linked these values
to the number of power supplies that each UPS is feeding (2) since this
maps better to physical topology and allows to throw a third or fourth
UPS into the mix without much configuration headache.


Multiple UPS shutdowns ordering
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

If you have multiple UPSes connected to your system, chances are that you
need to shut them down in a specific order.  The goal is to shut down
everything but the one keeping `upsmon` alive at first, then you do that
one last.

To set the order in which your UPSes receive the shutdown commands, define
the `sdorder` value in your 'ups.conf' device sections.

	[bigone]
		driver = usbhid-ups
		port = auto
		sdorder = 2

	[littleguy]
		driver = mge-shut
		port = /dev/ttyS0
		sdorder = 1

	[misc]
		driver = blazer_ser
		port = /dev/ttyS1
		sdorder = 0

The order runs from 0 to the highest number available.  So, for this
configuration, the order of shutdowns would be 'misc', 'littleguy',
and then 'bigone'.

NOTE: If you have a UPS that shouldn't be powered off when running
`upsdrvctl shutdown`, set its `sdorder` to `-1`.


Other redundancy configurations
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

There are a lot of ways to handle redundancy and they all come down to how many
power supplies, power cords and independent UPS connections you have.  A
system with a 1:1 cord:supply ratio has more wires stuffed behind it, but
it's much easier to move things around since any given UPS drives a smaller
percentage of the overall power.

More information can be found in the linkdoc:user-manual[NUT user manual],
and the various link:man/index.html[user manual pages].