# Deploy CockroachDB on Microsoft Azure

This page shows you how to manually deploy a secure multi-node CockroachDB cluster on Microsoft Azure, using Azure's managed load balancing service to distribute client traffic.

If you are only testing CockroachDB, or you are not concerned with protecting network communication with TLS encryption, you can use an insecure cluster instead. Select Insecure above for instructions.

Tip:

To try CockroachDB Cloud instead of running CockroachDB yourself, refer to the Cloud Quickstart.

## Before you begin

### Requirements

- You must have CockroachDB installed locally. This is necessary for generating and managing your deployment's certificates.

- You must have SSH access to each machine. This is necessary for distributing and starting CockroachDB binaries.

- Your network configuration must allow TCP communication on the following ports:

  - `26257` for intra-cluster and client-cluster communication
  - `8080` to expose your Admin UI

- Carefully review the Production Checklist and recommended Topology Patterns.

- Run each node on a separate machine. Since CockroachDB replicates across nodes, running more than one node per machine increases the risk of data loss if a machine fails. Likewise, if a machine has multiple disks or SSDs, run one node with multiple `--store` flags and not one node per disk. For more details about stores, see Start a Node.

- When starting each node, use the `--locality` flag to describe the node's location, for example, `--locality=region=west,zone=us-west-1`. The key-value pairs should be ordered from most to least inclusive, and the keys and order of key-value pairs must be the same on all nodes.

- When deploying in a single availability zone:

  - To be able to tolerate the failure of any 1 node, use at least 3 nodes with the `default` 3-way replication factor. In this case, if 1 node fails, each range retains 2 of its 3 replicas, a majority.
  - To be able to tolerate 2 simultaneous node failures, use at least 5 nodes and increase the `default` replication factor for user data to 5. The replication factor for important internal data is 5 by default, so no adjustments are needed for internal data. In this case, if 2 nodes fail at the same time, each range retains 3 of its 5 replicas, a majority.

- When deploying across multiple availability zones:

  - To be able to tolerate the failure of 1 entire AZ in a region, use at least 3 AZs per region and set `--locality` on each node to spread data evenly across regions and AZs. In this case, if 1 AZ goes offline, the 2 remaining AZs retain a majority of replicas.
  - To be able to tolerate the failure of 1 entire region, use at least 3 regions.

### Recommendations

- Decide how you want to access your Admin UI:

  Access Level | Description
  --- | ---
  Partially open | Set a firewall rule to allow only specific IP addresses to communicate on port `8080`.
  Completely open | Set a firewall rule to allow all IP addresses to communicate on port `8080`.
  Completely closed | Set a firewall rule to disallow all communication on port `8080`. In this case, a machine with SSH access to a node could use an SSH tunnel to access the Admin UI.

## Step 1. Configure your network

CockroachDB requires TCP communication on two ports:

- 26257 (`tcp:26257`) for inter-node communication (i.e., working as a cluster), for applications to connect to the load balancer, and for routing from the load balancer to nodes
- 8080 (`tcp:8080`) for exposing your Admin UI

To enable this in Azure, you must create a Resource Group, Virtual Network, and Network Security Group.

1. Create a Resource Group.
2. Create a Virtual Network that uses your Resource Group.

3. Create a Network Security Group that uses your Resource Group, and then add the following inbound rules to it:

   - Admin UI support:

     Field | Recommended Value
     --- | ---
     Name | cockroachadmin
     Source | IP Addresses
     Source IP addresses/CIDR ranges | Your local network’s IP ranges
     Source port ranges | *
     Destination | Any
     Destination port range | 8080
     Protocol | TCP
     Action | Allow
     Priority | Any value > 1000

   - Application support:

     Tip:
     If your application is also hosted on the same Azure Virtual Network, you will not need to create a firewall rule for your application to communicate with your load balancer.

     Field | Recommended Value
     --- | ---
     Name | cockroachapp
     Source | IP Addresses
     Source IP addresses/CIDR ranges | Your local network’s IP ranges
     Source port ranges | *
     Destination | Any
     Destination port range | 26257
     Protocol | TCP
     Action | Allow
     Priority | Any value > 1000

## Step 2. Create VMs

Create Linux VMs for each node you plan to have in your cluster. If you plan to run a sample workload against the cluster, create a separate VM for that workload.

- Run at least 3 nodes to ensure survivability.

- Use compute-optimized F-series VMs with Premium Storage or local SSD storage with a Linux filesystem such as `ext4` (not the Windows `ntfs` filesystem). For example, Cockroach Labs has used `Standard_F16s_v2` VMs (16 vCPUs and 32 GiB of RAM per VM) for internal testing.

  - If you choose local SSD storage, on reboot, the VM can come back with the `ntfs` filesystem. Be sure your automation monitors for this and reformats the disk to the Linux filesystem you chose initially.

- Do not use "burstable" B-series VMs, which limit the load on a single core. Also, Cockroach Labs has experienced data corruption issues on A-series VMs and irregular disk performance on D-series VMs, so we recommend avoiding those as well.

- When creating the VMs, make sure to select the Resource Group, Virtual Network, and Network Security Group you created.

For more details, see Hardware Recommendations and Cluster Topology.

## Step 3. Synchronize clocks

CockroachDB requires moderate levels of clock synchronization to preserve data consistency. For this reason, when a node detects that its clock is out of sync with at least half of the other nodes in the cluster by 80% of the maximum offset allowed (500ms by default), it spontaneously shuts down. This avoids the risk of consistency anomalies, but it's best to prevent clocks from drifting too far in the first place by running clock synchronization software on each node.

`ntpd` should keep offsets in the single-digit milliseconds, so that software is featured here. However, to run `ntpd` properly on Azure VMs, it's necessary to first unbind the Time Synchronization device used by the Hyper-V technology running Azure VMs; this device aims to synchronize time between the VM and its host operating system but has been known to cause problems.

1. SSH to the first machine.

2. Find the ID of the Hyper-V Time Synchronization device:

       $ curl -O https://raw.githubusercontent.com/torvalds/linux/master/tools/hv/lsvmbus

       $ python lsvmbus -vv | grep -w "Time Synchronization" -A 3

       VMBUS ID 12: Class_ID = {9527e630-d0ae-497b-adce-e80ab0175caf} - [Time Synchronization]
           Device_ID = {2dd1ce17-079e-403c-b352-a1921ee207ee}
           Sysfs path: /sys/bus/vmbus/devices/2dd1ce17-079e-403c-b352-a1921ee207ee
           Rel_ID=12, target_cpu=0

3. Unbind the device, using the `Device_ID` from the previous command's output:

       $ echo <DEVICE_ID> | sudo tee /sys/bus/vmbus/drivers/hv_util/unbind

4. Install the `ntp` package:

       $ sudo apt-get install ntp

5. Stop the NTP daemon:

       $ sudo service ntp stop

6. Sync the machine's clock with Google's NTP service:

       $ sudo ntpd -b time.google.com

   To make this change permanent, in the `/etc/ntp.conf` file, remove or comment out any lines starting with `server` or `pool` and add the following lines:

       server time1.google.com iburst
       server time2.google.com iburst
       server time3.google.com iburst
       server time4.google.com iburst

   Restart the NTP daemon:

       $ sudo service ntp start

   Note:

   We recommend Google's NTP service because it handles "smearing" the leap second. If you use a different NTP service that doesn't smear the leap second, be sure to configure client-side smearing in the same way on each machine. See the Production Checklist for details.

7. Verify that the machine is using a Google NTP server:

       $ sudo ntpq -p

   The active NTP server will be marked with an asterisk.

8. Repeat these steps for each machine where a CockroachDB node will run.

## Step 4. Set up load balancing

Each CockroachDB node is an equally suitable SQL gateway to your cluster, but to ensure client performance and reliability, it's important to use load balancing:

- Performance: Load balancers spread client traffic across nodes. This prevents any one node from being overwhelmed by requests and improves overall cluster performance (queries per second).

- Reliability: Load balancers decouple client health from the health of a single CockroachDB node. In cases where a node fails, the load balancer redirects client traffic to available nodes.

Microsoft Azure offers fully-managed load balancing to distribute traffic between instances.

1. Add Azure load balancing. Be sure to:

   - Set forwarding rules to route TCP traffic from the load balancer's port 26257 to port 26257 on the nodes.
   - Configure health checks to use HTTP port 8080 and path `/health?ready=1`. This health endpoint ensures that load balancers do not direct traffic to nodes that are live but not ready to receive requests.

2. Note the provisioned IP Address for the load balancer. You'll use this later to test load balancing and to connect your application to the cluster.

Note:
If you would prefer to use HAProxy instead of Azure's managed load balancing, see the On-Premises tutorial for guidance.

## Step 5. Generate certificates

You can use either `cockroach cert` commands or `openssl` commands to generate security certificates. This section features the `cockroach cert` commands.

Locally, you'll need to create the following certificates and keys:

- A certificate authority (CA) key pair (`ca.crt` and `ca.key`).
- A node key pair for each node, issued to its IP addresses and any common names the machine uses, as well as to the IP addresses and common names for machines running load balancers.
- A client key pair for the `root` user. You'll use this to run a sample workload against the cluster as well as some `cockroach` client commands from your local machine.

Tip:
Before beginning, it's useful to collect each of your machine's internal and external IP addresses, as well as any server names you want to issue certificates for.

1. Install CockroachDB on your local machine, if you haven't already.

2. Create two directories:

       $ mkdir certs

       $ mkdir my-safe-directory

   - `certs`: You'll generate your CA certificate and all node and client certificates and keys in this directory and then upload some of the files to your nodes.
   - `my-safe-directory`: You'll generate your CA key in this directory and then reference the key when generating node and client certificates. After that, you'll keep the key safe and secret; you will not upload it to your nodes.

3. Create the CA certificate and key:

       $ cockroach cert create-ca \
       --certs-dir=certs \
       --ca-key=my-safe-directory/ca.key

4. Create the certificate and key for the first node, issued to all common names you might use to refer to the node as well as to the load balancer instances:

       $ cockroach cert create-node \
       <node1 internal IP address> \
       <node1 external IP address> \
       <node1 hostname>  \
       <other common names for node1> \
       localhost \
       127.0.0.1 \
       <load balancer IP address> \
       <load balancer hostname>  \
       <other common names for load balancer instances> \
       --certs-dir=certs \
       --ca-key=my-safe-directory/ca.key

5. Upload the CA certificate and node certificate and key to the first node:

       $ ssh <username>@<node1 address> "mkdir certs"

       $ scp certs/ca.crt \
       certs/node.crt \
       certs/node.key \
       <username>@<node1 address>:~/certs

6. Delete the local copy of the node certificate and key:

       $ rm certs/node.crt certs/node.key

   Note:

   This is necessary because the certificates and keys for additional nodes will also be named `node.crt` and `node.key`. As an alternative to deleting these files, you can run the next `cockroach cert create-node` commands with the `--overwrite` flag.

7. Create the certificate and key for the second node, issued to all common names you might use to refer to the node as well as to the load balancer instances:

       $ cockroach cert create-node \
       <node2 internal IP address> \
       <node2 external IP address> \
       <node2 hostname>  \
       <other common names for node2> \
       localhost \
       127.0.0.1 \
       <load balancer IP address> \
       <load balancer hostname>  \
       <other common names for load balancer instances> \
       --certs-dir=certs \
       --ca-key=my-safe-directory/ca.key

8. Upload the CA certificate and node certificate and key to the second node:

       $ ssh <username>@<node2 address> "mkdir certs"

       $ scp certs/ca.crt \
       certs/node.crt \
       certs/node.key \
       <username>@<node2 address>:~/certs

9. Repeat steps 6 - 8 for each additional node.

10. Create a client certificate and key for the `root` user:

        $ cockroach cert create-client \
        root \
        --certs-dir=certs \
        --ca-key=my-safe-directory/ca.key

11. Upload the CA certificate and client certificate and key to the machine where you will run a sample workload:

        $ ssh <username>@<workload address> "mkdir certs"

        $ scp certs/ca.crt \
        certs/client.root.crt \
        certs/client.root.key \
        <username>@<workload address>:~/certs

    In later steps, you'll also use the `root` user's certificate to run `cockroach` client commands from your local machine. If you might also want to run `cockroach` client commands directly on a node (e.g., for local debugging), you'll need to copy the `root` user's certificate and key to that node as well.

Note:

On accessing the Admin UI in a later step, your browser will consider the CockroachDB-created certificate invalid and you’ll need to click through a warning message to get to the UI. You can avoid this issue by using a certificate issued by a public CA.

## Step 6. Start nodes

You can start the nodes manually or automate the process using systemd.

For each initial node of your cluster, complete the following steps:

Note:
After completing these steps, nodes will not yet be live. They will complete the startup process and join together to form a cluster as soon as the cluster is initialized in the next step.

1. SSH to the machine where you want the node to run.

2. Download the CockroachDB archive for Linux, and extract the binary:

       $ curl https://binaries.cockroachdb.com/cockroach-v20.1.17.linux-amd64.tgz \
       | tar -xz

3. Copy the binary into the `PATH`:

       $ cp -i cockroach-v20.1.17.linux-amd64/cockroach /usr/local/bin/

   If you get a permissions error, prefix the command with `sudo`.

4. Run the `cockroach start` command:

       $ cockroach start \
       --certs-dir=certs \
       --advertise-addr=<node1 address> \
       --join=<node1 address>,<node2 address>,<node3 address> \
       --cache=.25 \
       --max-sql-memory=.25 \
       --background

   This command primes the node to start, using the following flags:

   Flag | Description
   --- | ---
   `--certs-dir` | Specifies the directory where you placed the `ca.crt` file and the `node.crt` and `node.key` files for the node.
   `--advertise-addr` | Specifies the IP address/hostname and port to tell other nodes to use. The port number can be omitted, in which case it defaults to `26257`. This value must route to an IP address the node is listening on (with `--listen-addr` unspecified, the node listens on all IP addresses). In some networking scenarios, you may need to use `--advertise-addr` and/or `--listen-addr` differently. For more details, see Networking.
   `--join` | Identifies the address of 3-5 of the initial nodes of the cluster. These addresses should match the addresses that the target nodes are advertising.
   `--cache` `--max-sql-memory` | Increases the node's cache size to 25% of available system memory to improve read performance. The capacity for in-memory SQL processing defaults to 25% of system memory but can be raised, if necessary, to increase the number of simultaneous client connections allowed by the node as well as the node's capacity for in-memory processing of rows when using `ORDER BY`, `GROUP BY`, `DISTINCT`, joins, and window functions. For more details, see Cache and SQL Memory Size.
   `--background` | Starts the node in the background so you gain control of the terminal to issue more commands.

   When deploying across multiple datacenters, or when there is otherwise high latency between nodes, it is recommended to set `--locality` as well. It is also required to use certain enterprise features. For more details, see Locality.

   For other flags not explicitly set, the command uses default values. For example, the node stores data in `--store=cockroach-data` and binds Admin UI HTTP requests to `--http-addr=<node1 address>:8080`. To set these options manually, see Start a Node.

5. Repeat these steps for each additional node that you want in your cluster.

For each initial node of your cluster, complete the following steps:

Note:
After completing these steps, nodes will not yet be live. They will complete the startup process and join together to form a cluster as soon as the cluster is initialized in the next step.

1. SSH to the machine where you want the node to run. Ensure you are logged in as the `root` user.

2. Download the CockroachDB archive for Linux, and extract the binary:

       $ curl https://binaries.cockroachdb.com/cockroach-v20.1.17.linux-amd64.tgz \
       | tar -xz

3. Copy the binary into the `PATH`:

       $ cp -i cockroach-v20.1.17.linux-amd64/cockroach /usr/local/bin/

   If you get a permissions error, prefix the command with `sudo`.

4. Create the Cockroach directory:

       $ mkdir /var/lib/cockroach

5. Create a Unix user named `cockroach`:

       $ useradd cockroach

6. Move the `certs` directory to the `cockroach` directory.

       $ mv certs /var/lib/cockroach/

7. Change the ownership of the `cockroach` directory to the user `cockroach`:

       $ chown -R cockroach /var/lib/cockroach

8. Download the sample configuration template and save the file in the `/etc/systemd/system/` directory:

       $ wget -qO- https://raw.githubusercontent.com/cockroachdb/docs/master/_includes/v20.1/prod-deployment/securecockroachdb.service

   Alternatively, you can create the file yourself and copy the script into it:

       [Unit]
       Description=Cockroach Database cluster node
       Requires=network.target
       [Service]
       Type=notify
       WorkingDirectory=/var/lib/cockroach
       ExecStart=/usr/local/bin/cockroach start --certs-dir=certs --advertise-addr=<node1 address> --join=<node1 address>,<node2 address>,<node3 address> --cache=.25 --max-sql-memory=.25
       TimeoutStopSec=60
       Restart=always
       RestartSec=10
       StandardOutput=syslog
       StandardError=syslog
       SyslogIdentifier=cockroach
       User=cockroach
       [Install]
       WantedBy=default.target

9. In the sample configuration template, specify values for the following flags:

   Flag | Description
   --- | ---
   `--advertise-addr` | Specifies the IP address/hostname and port to tell other nodes to use. The port number can be omitted, in which case it defaults to `26257`. This value must route to an IP address the node is listening on (with `--listen-addr` unspecified, the node listens on all IP addresses). In some networking scenarios, you may need to use `--advertise-addr` and/or `--listen-addr` differently. For more details, see Networking.
   `--join` | Identifies the address of 3-5 of the initial nodes of the cluster. These addresses should match the addresses that the target nodes are advertising.

   When deploying across multiple datacenters, or when there is otherwise high latency between nodes, it is recommended to set `--locality` as well. It is also required to use certain enterprise features. For more details, see Locality.

   For other flags not explicitly set, the command uses default values. For example, the node stores data in `--store=cockroach-data` and binds Admin UI HTTP requests to `--http-addr=localhost:8080`. To set these options manually, see Start a Node.

10. Start the CockroachDB cluster:

        $ systemctl start securecockroachdb

11. Repeat these steps for each additional node that you want in your cluster.

Note:

`systemd` handles node restarts in case of node failure. To stop a node without `systemd` restarting it, run `systemctl stop securecockroachdb`

## Step 7. Initialize the cluster

On your local machine, run the `cockroach init` command to complete the node startup process and have them join together as a cluster:

    $ cockroach init --certs-dir=certs --host=<address of any node>

After running this command, each node prints helpful details to the standard output, such as the CockroachDB version, the URL for the admin UI, and the SQL URL for clients.

## Step 8. Test the cluster

CockroachDB replicates and distributes data behind-the-scenes and uses a Gossip protocol to enable each node to locate data across the cluster. Once a cluster is live, any node can be used as a SQL gateway.

When using a load balancer, you should issue commands directly to the load balancer, which then routes traffic to the nodes.

Use the built-in SQL client locally as follows:

1. On your local machine, launch the built-in SQL client, with the `--host` flag set to the address of the load balancer:

       $ cockroach sql --certs-dir=certs --host=<address of load balancer>

2. Create a `securenodetest` database:

       > CREATE DATABASE securenodetest;

3. View the cluster's databases, which will include `securenodetest`:

       > SHOW DATABASES;

       +--------------------+
       |      Database      |
       +--------------------+
       | crdb_internal      |
       | information_schema |
       | securenodetest     |
       | pg_catalog         |
       | system             |
       +--------------------+
       (5 rows)

4. Use `\q` to exit the SQL shell.

## Step 9. Run a sample workload

CockroachDB offers a pre-built `workload` binary for Linux that includes several load generators for simulating client traffic against your cluster. This step features CockroachDB's version of the TPC-C workload.

Note:

Be sure that you have set up an inbound rule that allows traffic from the application to the load balancer. In this case, you will run the sample workload on one of your instances. The traffic source for your inbound rule should therefore be the internal (private) IP address of that instance. To find this, open the Instances section of the Amazon EC2 console and click on the instance.

Tip:
For comprehensive guidance on benchmarking CockroachDB with TPC-C, see our Performance Benchmarking white paper.

1. SSH to the machine where you want to run the sample TPC-C workload.

   This should be a machine that is not running a CockroachDB node, and it should already have a `certs` directory containing `ca.crt`, `client.root.crt`, and `client.root.key` files.

2. Download `workload` and make it executable:

       $ wget https://edge-binaries.cockroachdb.com/cockroach/workload.LATEST ; chmod 755 workload.LATEST

3. Rename and copy `workload` into the `PATH`:

       $ cp -i workload.LATEST /usr/local/bin/workload

4. Start the TPC-C workload, pointing it at the IP address of the load balancer and the location of the `ca.crt`, `client.root.crt`, and `client.root.key` files:

       $ workload run tpcc \
       --drop \
       --init \
       --duration=20m \
       --tolerate-errors \
       "postgresql://root@<IP ADDRESS OF LOAD BALANCER>:26257/tpcc?sslmode=verify-full&sslrootcert=certs/ca.crt&sslcert=certs/client.root.crt&sslkey=certs/client.root.key"

   This command runs the TPC-C workload against the cluster for 20 minutes, loading 1 "warehouse" of data initially and then issuing about 12 queries per minute via 10 "worker" threads. These workers share SQL connections since individual workers are idle for long periods of time between queries.

   Tip:
   For more `tpcc` options, use `workload run tpcc --help`. For details about other load generators included in `workload`, use `workload run --help`.

5. To monitor the load generator's progress, open the Admin UI by pointing a browser to the address in the `admin` field in the standard output of any node on startup.

   For each user who should have access to the Admin UI for a secure cluster, create a user with a password and assign them to an `admin` role if necessary. On accessing the Admin UI, the users will see a Login screen, where they will need to enter their usernames and passwords.

   Since the load generator is pointed at the load balancer, the connections will be evenly distributed across nodes. To verify this, click Metrics on the left, select the SQL dashboard, and then check the SQL Connections graph. You can use the Graph menu to filter the graph for specific nodes.

## Step 10. Monitor the cluster

Despite CockroachDB's various built-in safeguards against failure, it is critical to actively monitor the overall health and performance of a cluster running in production and to create alerting rules that promptly send notifications when there are events that require investigation or intervention.

For details about available monitoring options and the most important events and metrics to alert on, see Monitoring and Alerting.

## Step 11. Scale the cluster

You can start the nodes manually or automate the process using systemd.

For each additional node you want to add to the cluster, complete the following steps:

1. SSH to the machine where you want the node to run.

2. Download the CockroachDB archive for Linux, and extract the binary:

       $ curl https://binaries.cockroachdb.com/cockroach-v20.1.17.linux-amd64.tgz \
       | tar -xz

3. Copy the binary into the `PATH`:

       $ cp -i cockroach-v20.1.17.linux-amd64/cockroach /usr/local/bin/

   If you get a permissions error, prefix the command with `sudo`.

4. Run the `cockroach start` command, passing the new node's address as the `--advertise-addr` flag and pointing `--join` to the three existing nodes (also include `--locality` if you set it earlier).

       $ cockroach start \
       --certs-dir=certs \
       --advertise-addr=<node4 address> \
       --join=<node1 address>,<node2 address>,<node3 address> \
       --cache=.25 \
       --max-sql-memory=.25 \
       --background

5. Update your load balancer to recognize the new node.

For each additional node you want to add to the cluster, complete the following steps:

1. SSH to the machine where you want the node to run. Ensure you are logged in as the `root` user.

2. Download the CockroachDB archive for Linux, and extract the binary:

       $ curl https://binaries.cockroachdb.com/cockroach-v20.1.17.linux-amd64.tgz \
       | tar -xz

3. Copy the binary into the `PATH`:

       $ cp -i cockroach-v20.1.17.linux-amd64/cockroach /usr/local/bin/

   If you get a permissions error, prefix the command with `sudo`.

4. Create the Cockroach directory:

       $ mkdir /var/lib/cockroach

5. Create a Unix user named `cockroach`:

       $ useradd cockroach

6. Move the `certs` directory to the `cockroach` directory.

       $ mv certs /var/lib/cockroach/

7. Change the ownership of the `cockroach` directory to the user `cockroach`:

       $ chown -R cockroach /var/lib/cockroach

8. Download the sample configuration template:

       $ wget -qO- https://raw.githubusercontent.com/cockroachdb/docs/master/_includes/v20.1/prod-deployment/securecockroachdb.service

   Alternatively, you can create the file yourself and copy the script into it:

       [Unit]
       Description=Cockroach Database cluster node
       Requires=network.target
       [Service]
       Type=notify
       WorkingDirectory=/var/lib/cockroach
       ExecStart=/usr/local/bin/cockroach start --certs-dir=certs --advertise-addr=<node1 address> --join=<node1 address>,<node2 address>,<node3 address> --cache=.25 --max-sql-memory=.25
       TimeoutStopSec=60
       Restart=always
       RestartSec=10
       StandardOutput=syslog
       StandardError=syslog
       SyslogIdentifier=cockroach
       User=cockroach
       [Install]
       WantedBy=default.target

   Save the file in the `/etc/systemd/system/` directory.

9. Customize the sample configuration template for your deployment:

   Specify values for the following flags in the sample configuration template:

   Flag | Description
   --- | ---
   `--advertise-addr` | Specifies the IP address/hostname and port to tell other nodes to use. The port number can be omitted, in which case it defaults to `26257`. This value must route to an IP address the node is listening on (with `--listen-addr` unspecified, the node listens on all IP addresses). In some networking scenarios, you may need to use `--advertise-addr` and/or `--listen-addr` differently. For more details, see Networking.
   `--join` | Identifies the address of 3-5 of the initial nodes of the cluster. These addresses should match the addresses that the target nodes are advertising.

10. Repeat these steps for each additional node that you want in your cluster.

## Step 12. Use the database

Now that your deployment is working, you can:

1. Implement your data model.
2. Create users and grant them privileges.
3. Connect your application. Be sure to connect your application to the load balancer, not to a CockroachDB node.

You may also want to adjust the way the cluster replicates data. For example, by default, a multi-node cluster replicates all data 3 times; you can change this replication factor or create additional rules for replicating individual databases and tables differently. For more information, see Configure Replication Zones.

Warning:

When running a cluster of 5 nodes or more, it's safest to increase the replication factor for important internal data to 5, even if you do not do so for user data. For the cluster as a whole to remain available, the ranges for this internal data must always retain a majority of their replicas.

## See also

- Production Checklist
- Manual Deployment
- Orchestrated Deployment
- Monitoring and Alerting
- Performance Benchmarking
- Performance Tuning
- Local Deployment