bring back old docs that were containing missing information (#17146)

* Create deployment-strategies.md

* Create start-stop-restart.md

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+# Deployment strategies
+
+
+## Deployment Options Overview
+
+This section provides a quick overview of a few common deployment options. The next sections go into configuration examples and further reading.
+
+### Stand-alone Deployment
+
+To help our users have a complete experience of Netdata when they install it for the first time, a Netdata Agent with default configuration
+is a complete monitoring solution out of the box, having all these features enabled and available.
+
+The Agent will act as a _stand-alone_ Agent by default, and this is great to start out with for small setups and home labs. By [connecting each Agent to Cloud](https://github.com/netdata/netdata/blob/master/src/claim/README.md), you can see an overview of all your nodes, with aggregated charts and centralized alerting, without setting up a Parent.
+
+![image](https://github.com/netdata/netdata/assets/116741/6a638175-aec4-4d46-85a6-520c283ab6a8)
+
+### Parent – Child Deployment
+
+An Agent connected to a Parent is called a _Child_. It will _stream_ metrics to its Parent. The Parent can then take care of storing metrics on behalf of that node (with longer retention), handle metrics queries for showing dashboards, and provide alerting.
+
+When using Cloud, it is recommended that just the Parent is connected to Cloud. Child Agents can then be configured to have short retention, in RAM instead of on Disk, and have alerting and other features disabled. Because they don't need to connect to Cloud themselves, those children can then be further secured by not allowing outbound traffic.
+
+![image](https://github.com/netdata/netdata/assets/116741/cb65698d-a6b7-43ee-a2d1-c30d0a46f084)
+
+This setup allows for leaner Child nodes and is good for setups with more than a handful of nodes. Metrics data remains accessible if the Child node is temporarily unavailable or decommissioned, although there is no failover in case the Parent becomes unavailable.
+
+
+### Active–Active Parent Deployment
+
+For high availability, Parents can be configured to stream data for their children between them, and keep the data sets in sync. Child Agents are configured with the addresses of both Parent Agents, but will only stream to one of them at a time. When that Parent becomes unavailable, it reconnects to another. When the first Parent becomes available again, that Parent will catch up by receiving the backlog from the second.
+
+With both Parent Agents connected to Cloud, Cloud will route queries to either Parent transparently, depending on their availability. Alerts trigger on either Parent will stream to Cloud, and Cloud will deduplicate and debounce state changes to prevent spurious notifications.
+
+![image](https://github.com/netdata/netdata/assets/116741/6ae2b10c-7f7d-4503-aac4-0a9381c6f80b)
+
+
+## Configuration Details
+
+### Stand-alone Deployment
+
+The stand-alone setup is configured out of the box with reasonable defaults, but please consult our [configuration documentation](https://github.com/netdata/netdata/blob/master/docs/cloud/cheatsheet.md) for details, including the overview of [common configuration changes](https://github.com/netdata/netdata/blob/master/docs/configure/common-changes.md).
+
+### Parent – Child Deployment
+
+For setups involving Child and Parent Agents, the Agents need to be configured for [_streaming_](https://github.com/netdata/netdata/blob/master/src/streaming/README.md), through the configuration file `stream.conf`. This will instruct the Child to stream data to the Parent and the Parent to accept streaming connections for one or more Child Agents. To secure this connection, both need set up a shared API key (to replace the string `API_KEY` in the examples below). Additionally, the Child is configured with one or more addresses of Parent Agents (`PARENT_IP_ADDRESS`).
+
+An API key is a key created with `uuidgen` and is used for authentication and/or customization in the Parent side. I.e. a Child will stream using the API key, and a Parent is configured to accept connections from Child, but can also apply different options for children by using multiple different API keys. The easiest setup uses just one API key for all Child Agents.
+
+#### Child config
+
+As mentioned above, the recommendation is to not claim the Child to Cloud directly during your setup, avoiding establishing an [ACLK](https://github.com/netdata/netdata/blob/master/src/aclk/README.md) connection.
+
+To reduce the footprint of the Netdata Agent on your production system, some capabilities can be switched OFF on the Child and kept ON on the Parent. In this example, Machine Learning and Alerting are disabled in the Child, so that the Parent can take the load. We also use RAM instead of disk to store metrics with limited retention, covering temporary network issues.
+
+##### netdata.conf
+
+On the child node, edit `netdata.conf` by using the edit-config script: `/etc/netdata/edit-config netdata.conf` set the following parameters:
+
+```yaml
+[db]
+    # https://learn.netdata.cloud/docs/agent/database
+    # none = no retention, ram = some retention in ram
+    mode = ram
+    # The retention in seconds.
+    # This provides some tolerance to the time the child has to find a parent in
+    # order to transfer the data. For IoT this can be lowered to 120.
+    retention = 1200
+    # The granularity of metrics, in seconds.
+    # You may increase this to lower CPU resources.
+    update every = 1
+[ml]
+    # Disable Machine Learning
+    enabled = no
+[health]
+    # Disable Health Checks (Alerting)
+    enabled = no
+[web]
+    # Disable remote access to the local dashboard
+    bind to = lo
+[plugins]
+    # Uncomment the following line to disable all external plugins on extreme
+    # IoT cases by default.
+    # enable running new plugins = no
+```
+
+##### stream.conf
+
+To edit `stream.conf`, again use the edit-config script: `/etc/netdata/edit-config stream.conf`.
+
+Set the following parameters:
+
+```yaml
+[stream]
+    # Stream metrics to another Netdata
+    enabled = yes
+    # The IP and PORT of the parent
+    destination = PARENT_IP_ADDRESS:19999
+    # The shared API key, generated by uuidgen
+    api key = API_KEY
+```
+
+#### Parent config
+
+For the Parent, besides setting up streaming, the example will also provide an example configuration of multiple [tiers](https://github.com/netdata/netdata/blob/master/src/database/engine/README.md#tiering) of metrics [storage](https://github.com/netdata/netdata/blob/master/docs/store/change-metrics-storage.md), for 10 children, with about 2k metrics each.
+
+- 1s granularity at tier 0 for 1 week
+- 1m granularity at tier 1 for 1 month
+- 1h granularity at tier 2 for 1 year
+
+Requiring:
+
+- 25GB of disk
+- 3.5GB of RAM (2.5GB under pressure)
+
+##### netdata.conf
+
+On the Parent, edit `netdata.conf` with `/etc/netdata/edit-config netdata.conf` and set the following parameters:
+
+```yaml
+[db]
+    mode = dbengine
+    storage tiers = 3
+    # To allow memory pressure to offload index from ram
+    dbengine page descriptors in file mapped memory = yes
+    # storage tier 0
+    update every = 1
+    dbengine multihost disk space MB = 12000
+    dbengine page cache size MB = 1400
+    # storage tier 1
+    dbengine tier 1 page cache size MB = 512
+    dbengine tier 1 multihost disk space MB = 4096
+    dbengine tier 1 update every iterations = 60
+    dbengine tier 1 backfill = new
+    # storage tier 2
+    dbengine tier 2 page cache size MB = 128
+    dbengine tier 2 multihost disk space MB = 2048
+    dbengine tier 2 update every iterations = 60
+    dbengine tier 2 backfill = new
+[ml]
+    # Enabled by default
+    # enabled = yes
+[health]
+    # Enabled by default
+    # enabled = yes
+[web]
+    # Enabled by default
+    # bind to = *
+```
+
+##### stream.conf
+
+On the Parent node, edit `stream.conf` with `/etc/netdata/edit-config stream.conf`, and then set the following parameters:
+
+```yaml
+[API_KEY]
+    # Accept metrics streaming from other Agents with the specified API key
+    enabled = yes
+```
+
+### Active–Active Parent Deployment
+
+In order to setup active–active streaming between Parent 1 and Parent 2, Parent 1 needs to be instructed to stream data to Parent 2 and Parent 2 to stream data to Parent 1. The Child Agents need to be configured with the addresses of both Parent Agents. The Agent will only connect to one Parent at a time, falling back to the next if the previous failed. These examples use the same API key between Parent Agents as for connections from Child Agents.
+
+On both Netdata Parent and all Child Agents, edit `stream.conf` with `/etc/netdata/edit-config stream.conf`:
+
+##### stream.conf on Parent 1
+
+```yaml
+[stream]
+    # Stream metrics to another Netdata
+    enabled = yes
+    # The IP and PORT of Parent 2
+    destination = PARENT_2_IP_ADDRESS:19999
+    # This is the API key for the outgoing connection to Parent 2
+    api key = API_KEY
+[API_KEY]
+    # Accept metrics streams from Parent 2 and Child Agents
+    enabled = yes
+```
+
+##### stream.conf on Parent 2
+
+```yaml
+[stream]
+    # Stream metrics to another Netdata
+    enabled = yes
+    # The IP and PORT of Parent 1
+    destination = PARENT_1_IP_ADDRESS:19999
+    api key = API_KEY
+[API_KEY]
+    # Accept metrics streams from Parent 1 and Child Agents
+    enabled = yes
+```
+
+##### stream.conf on Child Agents
+
+```yaml
+[stream]
+    # Stream metrics to another Netdata
+    enabled = yes
+    # The IP and PORT of the parent
+    destination = PARENT_1_IP_ADDRESS:19999 PARENT_2_IP_ADDRESS:19999
+    # The shared API key, generated by uuidgen
+    api key = API_KEY
+```
+
+## Further Reading
+
+We strongly recommend the following configuration changes for production deployments:
+
+1. Understand Netdata's [security and privacy design](https://github.com/netdata/netdata/blob/master/docs/security-and-privacy-design/README.md) and 
+   [secure your nodes](https://github.com/netdata/netdata/blob/master/docs/category-overview-pages/secure-nodes.md)
+
+   To safeguard your infrastructure and comply with your organization's security policies.
+
+2. Set up [streaming and replication](https://github.com/netdata/netdata/blob/master/src/streaming/README.md) to:
+
+   - Offload Netdata Agents running on production systems and free system resources for the production applications running on them.
+   - Isolate production systems from the rest of the world and improve security.
+   - Increase data retention.
+   - Make your data highly available.
+
+3. [Optimize the Netdata Agents system utilization and performance](https://github.com/netdata/netdata/blob/master/docs/guides/configure/performance.md)
+
+   To save valuable system resources, especially when running on weak IoT devices.
+
+We also suggest that you:
+
+1. [Use Netdata Cloud to access the dashboards](https://github.com/netdata/netdata/blob/master/docs/quickstart/infrastructure.md)
+
+   For increased security, user management and access to our latest tools for advanced dashboarding and troubleshooting.
+
+2. [Change how long Netdata stores metrics](https://github.com/netdata/netdata/blob/master/docs/store/change-metrics-storage.md)
+
+   To control Netdata's memory use, when you have a lot of ephemeral metrics. 
+
+3. [Use host labels](https://github.com/netdata/netdata/blob/master/docs/guides/using-host-labels.md)
+
+   To organize systems, metrics, and alerts.
diff --git a/docs/maintenance/start-stop-restart.md b/docs/maintenance/start-stop-restart.md
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+# Start, stop, or restart the Netdata Agent
+
+When you install the Netdata Agent, the [daemon](https://github.com/netdata/netdata/blob/master/src/daemon/README.md) is 
+configured to start at boot and stop and restart/shutdown.
+
+You will most often need to _restart_ the Agent to load new or editing configuration files. 
+[Health configuration](#reload-health-configuration) files are the only exception, as they can be reloaded without restarting
+the entire Agent.
+
+Stopping or restarting the Netdata Agent will cause gaps in stored metrics until the `netdata` process initiates
+collectors and the database engine.
+
+## Using `systemctl`, `service`, or `init.d`
+
+This is the recommended way to start, stop, or restart the Netdata daemon.
+
+- To **start** Netdata, run `sudo systemctl start netdata`.
+- To **stop** Netdata, run `sudo systemctl stop netdata`.
+- To **restart** Netdata, run `sudo systemctl restart netdata`.
+
+If the above commands fail, or you know that you're using a non-systemd system, try using the `service` command:
+
+- **service**: `sudo service netdata start`, `sudo service netdata stop`, `sudo service netdata restart`
+
+## Using `netdata`
+
+Use the `netdata` command, typically located at `/usr/sbin/netdata`, to start the Netdata daemon. 
+
+```bash
+sudo netdata
+```
+
+If you start the daemon this way, close it with `sudo killall netdata`.
+
+## Using `netdatacli`
+
+The Netdata Agent also comes with a [CLI tool](https://github.com/netdata/netdata/blob/master/src/cli/README.md) capable of performing shutdowns. Start the Agent back up
+using your preferred method listed above.
+
+```bash
+sudo netdatacli shutdown-agent
+```
+
+## Netdata MSI installations
+
+Netdata provides an installer for Windows using WSL, on those installations by using a Windows terminal (e.g. the Command prompt or Windows Powershell) you can:
+
+- Start Netdata, by running `start-netdata`
+- Stop Netdata, by running `stop-netdata`
+- Restart Netdata, by running `restart-netdata`
+
+## Reload health configuration
+
+You do not need to restart the Netdata Agent between changes to health configuration files, such as specific health
+entities. Instead, use [`netdatacli`](#using-netdatacli) and the `reload-health` option to prevent gaps in metrics
+collection.
+
+```bash
+sudo netdatacli reload-health
+```
+
+If `netdatacli` doesn't work on your system, send a `SIGUSR2` signal to the daemon, which reloads health configuration
+without restarting the entire process.
+
+```bash
+killall -USR2 netdata
+```
+
+## Force stop stalled or unresponsive `netdata` processes
+
+In rare cases, the Netdata Agent may stall or not properly close sockets, preventing a new process from starting. In
+these cases, try the following three commands:
+
+```bash
+sudo systemctl stop netdata
+sudo killall netdata
+ps aux| grep netdata
+```
+
+The output of `ps aux` should show no `netdata` or associated processes running. You can now start the Netdata Agent
+again with `service netdata start`, or the appropriate method for your system.
+
+## Starting Netdata at boot
+
+In the `system` directory you can find scripts and configurations for the
+various distros.
+
+### systemd
+
+The installer already installs `netdata.service` if it detects a systemd system.
+
+To install `netdata.service` by hand, run:
+
+```sh
+# stop Netdata
+killall netdata
+
+# copy netdata.service to systemd
+cp system/netdata.service /etc/systemd/system/
+
+# let systemd know there is a new service
+systemctl daemon-reload
+
+# enable Netdata at boot
+systemctl enable netdata
+
+# start Netdata
+systemctl start netdata
+```
+
+### init.d
+
+In the system directory you can find `netdata-lsb`. Copy it to the proper place according to your distribution
+documentation. For Ubuntu, this can be done via running the following commands as root.
+
+```sh
+# copy the Netdata startup file to /etc/init.d
+cp system/netdata-lsb /etc/init.d/netdata
+
+# make sure it is executable
+chmod +x /etc/init.d/netdata
+
+# enable it
+update-rc.d netdata defaults
+```
+
+### openrc (gentoo)
+
+In the `system` directory you can find `netdata-openrc`. Copy it to the proper
+place according to your distribution documentation.
+
+### CentOS / Red Hat Enterprise Linux
+
+For older versions of RHEL/CentOS that don't have systemd, an init script is included in the system directory. This can
+be installed by running the following commands as root.
+
+```sh
+# copy the Netdata startup file to /etc/init.d
+cp system/netdata-init-d /etc/init.d/netdata
+
+# make sure it is executable
+chmod +x /etc/init.d/netdata
+
+# enable it
+chkconfig --add netdata
+```
+
+_There have been some recent work on the init script, see PR
+<https://github.com/netdata/netdata/pull/403>_
+
+### other systems
+
+You can start Netdata by running it from `/etc/rc.local` or equivalent.