Geo Clustering Guide

4.1 Booth configuration and setup options #

The default booth configuration is /etc/booth/booth.conf. This file must be the same on all sites of your Geo cluster, including the arbitrator or arbitrators. To keep the booth configuration synchronous across all sites and arbitrators, use Csync2, as described in Sezione 4.5, «Synchronizing the booth configuration to all sites and arbitrators».

Nota: Ownership of /etc/booth and files

The directory /etc/booth and all files therein need to belong to the user hacluster and the group haclient. Whenever you copy a new file from this directory, use the option -p for the cp command to preserve the ownership. Alternatively, when you create a new file, set the user and group afterward with chown hacluster:haclient FILE.

For setups including multiple Geo clusters, it is possible to «share» the same arbitrator (as of SUSE Linux Enterprise High Availability 12). By providing several booth configuration files, you can start multiple booth instances on the same arbitrator, with each booth instance running on a different port. That way, you can use one machine to serve as arbitrator for different Geo clusters. For details on how to configure booth for multiple Geo clusters, refer to Sezione 4.4, «Using a multi-tenant booth setup».

To prevent malicious parties from disrupting the booth service, you can configure authentication for talking to booth, based on a shared key. For details, see 5 in Esempio 4.1, «A booth configuration file». All hosts that communicate with booth servers need this key. Therefore make sure to include the key file in the Csync2 configuration or to synchronize it manually across all parties.

4.2 Automatic versus manual tickets #

A ticket grants the right to run certain resources on a specific cluster site. Two types of tickets are supported:

Automatic tickets are controlled by the boothd daemon.
Manual tickets are managed by the cluster administrator only.

Automatic and manual tickets have the following properties:

Automatic and manual tickets can be defined together. You can define and use both automatic and manual tickets within the same Geo cluster.
Manual ticket management remains manual. The automatic ticket management is not applied to manually controlled tickets. Manual tickets do not require any quorum elections, cannot fail over automatically, and do not have an expiry time.
Manual tickets are not moved automatically. Tickets that were manually granted to a site remain there until they are manually revoked. Even if a site goes offline, the ticket is not moved to another site. This behavior ensures that the services that depend on a ticket remain on a particular site and are not moved to another site.
Same commands for managing both types of tickets. The manual tickets are managed by the same commands as automatic tickets (grant or revoke, for example).
Arbitrators are not needed if only manual tickets are used. If you configure only manual tickets in a Geo cluster, arbitrators are not necessary, because manual ticket management does not require quorum decisions.

To configure tickets, use the /etc/booth/booth.conf configuration file (see Sezione 4.3, «Using the default booth setup» for further information).

4.3 Using the default booth setup #

If you have set up your basic Geo cluster with the bootstrap scripts as described in the Geo Clustering Quick Start, the scripts have created a default booth configuration on all sites with a minimal set of parameters. To extend or fine-tune the minimal booth configuration, have a look at Esempio 4.1 or at the examples in Sezione 4.4, «Using a multi-tenant booth setup».

To add or change parameters needed for booth, either edit the booth configuration files manually or use the YaST Geo Cluster module. To access the YaST module, start it from command line with yast2 geo-cluster (or start YaST and select High Availability › Geo Cluster).

Esempio 4.1: A booth configuration file #

transport = UDP 1
port = 9929 2
arbitrator = 192.168.203.100 3
site =  192.168.201.100 4
site =  192.168.202.100 4
authfile = /etc/booth/authkey 5
ticket = "ticket-nfs" 6
     mode = MANUAL 7
ticket = "ticketA" 6
     expire = 600 8
     timeout = 10 9
     retries = 5 10
     renewal-freq = 30 11
     before-acquire-handler12 = /etc/booth/ticket-A13 db-1 14
     acquire-after = 60 15
ticket = "ticketB" 6
     expire = 600 8
     timeout = 10 9
     retries = 5 10
     renewal-freq = 30 11
     before-acquire-handler12 = /etc/booth/ticket-B13 db-8 14
     acquire-after = 60 15

1	The transport protocol used for communication between the sites. Only UDP is supported, but other transport layers will follow in the future. Currently, this parameter can therefore be omitted.
2	The port to be used for communication between the booth instances at each site. When not using the default port (`9929`), choose a port that is not already used for different services. Make sure to open the port in the nodes' and arbitrators' firewall rules. The booth clients use TCP to communicate with the `boothd`. Booth always binds and listens to both UDP and TCP ports.
3	The IP address of the machine to use as arbitrator. Add an entry for each arbitrator you use in your Geo cluster setup.
4	The IP address used for the `boothd` on a site. Add an entry for each site you use in your Geo cluster setup. Make sure to insert the correct virtual IP addresses (`IPaddr2`) for each site, otherwise the booth mechanism will not work correctly. Booth works with both IPv4 and IPv6 addresses. If you have set up booth with the bootstrap scripts, the virtual IPs you have specified during setup have been written to the booth configuration already (and have been added to the cluster configuration, too). To set up the cluster resources manually, see Sezione 6.2, «Configuring a resource group for `boothd`».
5	Optional parameter. Enables booth authentication for clients and servers on the basis of a shared key. This parameter specifies the path to the key file. Key Requirements # The key can be either binary or text. If it is text, the following characters are ignored: leading and trailing white space, new lines. The key must be between 8 and 64 characters long. The key must belong to the user `hacluster` and the group `haclient`. The key must be readable only by the file owner.
6	The tickets to be managed by booth or a cluster administrator. For each ticket, add a `ticket` entry. For example, the ticket `ticket-nfs` specified here can be used for failover of NFS and DRBD as explained in https://documentation.suse.com/sbp/all/html/SBP-DRBD/index.html.
7	Optional parameter. Defines the ticket mode. By default, all tickets are managed by booth. To define tickets which are managed by the administrator (manual tickets), set the mode parameter to `MANUAL` or `manual`. Manual tickets do not have expire, renewal-freq, and retries parameters.
8	Optional parameter. Defines the ticket's expiry time in seconds. A site that has been granted a ticket renews the ticket regularly. If booth does not receive any information about renewal of the ticket within the defined expiry time, the ticket is revoked and granted to another site. If no expiry time is specified, the ticket expires after `600` seconds by default. The parameter should not be set to a value less than 120 seconds. The default value set by the bootstrap scripts is `600`.
9	Optional parameter. Defines a timeout period in seconds. After that time, booth resends packets if it did not receive a reply within this period. The timeout defined should be long enough to allow packets to reach other booth members (all arbitrators and sites).
10	Optional parameter. Defines how many times booth retries sending packets before giving up waiting for confirmation by other sites. Values smaller than `3` are invalid and prevent booth from starting.
11	Optional parameter. Sets the ticket renewal frequency period. Ticket renewal occurs every half expiry time by default. If the network reliability is often reduced over prolonged periods, it is advisable to renew more often. Before every renewal the `before-acquire-handler` is run.
12	Optional parameter. It supports one or more scripts. To use more than one script, each script can be responsible for different checks, like cluster state, data center connectivity, environment health sensors, and more. Store all scripts in the directory `/etc/booth.d/TICKET_NAME` and make sure they have the correct ownership (user `hacluster` and group `haclient`). Assign the directory name as a value to the parameter before-acquire-handler. The scripts in this directory are executed in alphabetical order. All scripts will be called before `boothd` tries to acquire or renew a ticket. For the ticket to be granted or renewed, all scripts must succeed. The semantics are the same as for a single script: On exit code other than `0`, `boothd` relinquishes the ticket.
13	The `/usr/share/booth/service-runnable` script is included in the product as an example. To use it, link it into the respective «ticket» directory: `#` `ln -s /usr/share/booth/service-runnable /etc/booth.d/TICKET_NAME` Assume that the `/etc/booth.dTICKET_NAME` directory contains the `service-runnable` script. This simple script is based on `crm_simulate`. It can be used to test whether a particular cluster resource can be run on the current cluster site. That means, it checks if the cluster is healthy enough to run the resource (all resource dependencies are fulfilled, the cluster partition has quorum, no dirty nodes, etc.). For example, if a service in the dependency chain has a fail count of `INFINITY` on all available nodes, the service cannot be run on that site. In that case, it is of no use to claim the ticket.
14	The resource to be tested by the `before-acquire-handler` (in this case, by the `service-runnable` script). You need to reference the resource that is protected by the respective ticket. In this example, resource `db-1` is protected by `ticketA` whereas `db-8` is protected by `ticketB`. The resource for DRBD (`ms_drbd_nfs`) is protected by the ticket `ticket-nfs`.
15	Optional parameter. After a ticket is lost, booth waits this time in addition before acquiring the ticket. This is to allow for the site that lost the ticket to relinquish the resources, by either stopping them or fencing a node. A typical delay might be `60` seconds, but ultimately it depends on the protected resources and the fencing configuration. The default value is `0`. If you are unsure how long stopping or demoting the resources or fencing a node may take (depending on the `loss-policy`), use this parameter to prevent resources from running on two sites at the same time.

4.3.1 Manually editing the booth configuration file #

Log in to a cluster node as root or equivalent.
If /etc/booth/booth.conf does not exist yet, copy the example booth configuration file /etc/booth/booth.conf.example to /etc/booth/booth.conf:
```
# cp -p /etc/booth/booth.conf.example /etc/booth/booth.conf
```
Edit /etc/booth/booth.conf according to Esempio 4.1, «A booth configuration file».
Verify your changes and save the file.
On all cluster nodes and arbitrators, open the port in the firewall that you have configured for booth. See Esempio 4.1, «A booth configuration file», position 2.

4.3.2 Setting up booth with YaST #

Log in to a cluster node as root or equivalent.
Start the YaST Geo Cluster module.
Choose to Edit an existing booth configuration file or click Add to create a new booth configuration file:
1. In the screen that appears configure the following parameters:
  - Configuration file. A name for the booth configuration file. YaST suggests booth by default. This results in the booth configuration being written to /etc/booth/booth.conf. Only change this value if you need to set up multiple booth instances for different Geo clusters as described in Sezione 4.4, «Using a multi-tenant booth setup».
  - Transport. The transport protocol used for communication between the sites. Only UDP is supported, but other transport layers will follow in the future. See also Esempio 4.1, «A booth configuration file», position 1.
  - Port. The port to be used for communication between the booth instances at each site. See also Esempio 4.1, «A booth configuration file», position 2.
  - Arbitrator. The IP address of the machine to use as arbitrator. See also Esempio 4.1, «A booth configuration file», position 3.
    To specify an Arbitrator, click Add. In the dialog that opens, enter the IP address of your arbitrator and click OK.
  - Site. The IP address used for the boothd on a site. See also Esempio 4.1, «A booth configuration file», position 4.
    To specify a Site of your Geo cluster, click Add. In the dialog that opens, enter the IP address of one site and click OK.
  - Ticket. The tickets to be managed by booth or a cluster administrator. See also Esempio 4.1, «A booth configuration file», position 6.
    To specify a Ticket, click Add. In the dialog that opens, enter a unique Ticket name. If you need to define multiple tickets with the same parameters and values, save configuration effort by creating a «ticket template» that specifies the default parameters and values for all tickets. To do so, use __default__ as Ticket name.
  - Authentication. To enable authentication for booth, click Authentication and in the dialog that opens, activate Enable Security Auth. If you already have an existing key, specify the path and file name in Authentication file. To generate a key file for a new Geo cluster, click Generate Authentication Key File. The key is created and written to the location specified in Authentication file.
    Additionally, you can specify optional parameters for your ticket. For an overview, see Esempio 4.1, «A booth configuration file», positions 7 to 15.
    Click OK to confirm your changes.
  Figura 4.1: Example ticket dependency #
2. Click OK to close the current booth configuration screen. YaST shows the name of the booth configuration file that you have defined.
Before closing the YaST module, switch to the Firewall Configuration category.
To open the port you have configured for booth, enable Open Port in Firewall.
Importante: Firewall setting for local machine only
The firewall setting is only applied to the current machine. It opens the UDP/TCP ports for all ports that have been specified in /etc/booth/booth.conf or any other booth configuration files (see Sezione 4.4, «Using a multi-tenant booth setup»).
Make sure to open the respective ports on all other cluster nodes and arbitrators of your Geo cluster setup, too. Do so either manually or by synchronizing the following files with Csync2:
- /usr/lib/firewalld
- /usr/lib/firewalld/services/booth.xml
Click Finish to confirm all settings and close the YaST module. Depending on the NAME of the Configuration File specified in Passo 3.a, the configuration is written to /etc/booth/NAME.conf.

4.4 Using a multi-tenant booth setup #

For setups including multiple Geo clusters, it is possible to «share» the same arbitrator (as of SUSE Linux Enterprise High Availability 12). By providing several booth configuration files, you can start multiple booth instances on the same arbitrator, with each booth instance running on a different port. That way, you can use one machine to serve as arbitrator for different Geo clusters.

Let us assume you have two Geo clusters, one in EMEA (Europe, the Middle East and Africa), and one in the Asia-Pacific region (APAC).

To use the same arbitrator for both Geo clusters, create two configuration files in the /etc/booth directory: /etc/booth/emea.conf and /etc/booth/apac.conf. Both must minimally differ in the following parameters:

The port used for the communication of the booth instances.
The sites belonging to the different Geo clusters that the arbitrator is used for.

Esempio 4.2: /etc/booth/apac.conf #

transport = UDP 1
port = 9133 2
arbitrator = 192.168.203.100 3
site = 192.168.2.254 4
site = 192.168.1.112 4
authfile = /etc/booth/authkey-apac 5
ticket ="tkt-db-apac-intern" 6
     timeout = 10
     retries = 5
     renewal-freq = 60
     before-acquire-handler12 = /usr/share/booth/service-runnable13 db-apac-intern 14
ticket = "tkt-db-apac-cust" 6
     timeout = 10
     retries = 5
     renewal-freq = 60
     before-acquire-handler = /usr/share/booth/service-runnable db-apac-cust

Esempio 4.3: /etc/booth/emea.conf #

transport = UDP 1
port = 9150 2
arbitrator = 192.168.203.100 3
site = 192.168.201.100 4
site = 192.168.202.100 4
authfile = /etc/booth/authkey-emea 5
ticket = "tkt-sap-crm" 6
     expire = 900
     renewal-freq = 60
     before-acquire-handler12 = /usr/share/booth/service-runnable13 sap-crm 14
ticket = "tkt-sap-prod" 6
     expire = 600
     renewal-freq = 60
     before-acquire-handler = /usr/share/booth/service-runnable sap-prod

1	The transport protocol used for communication between the sites. Only UDP is supported, but other transport layers will follow in the future. Currently, this parameter can therefore be omitted.
2	The port to be used for communication between the booth instances at each site. The configuration files use different ports to allow for start of multiple booth instances on the same arbitrator.
3	The IP address of the machine to use as arbitrator. In the examples above, we use the same arbitrator for different Geo clusters.
4	The IP address used for the `boothd` on a site. The sites defined in both booth configuration files are different, because they belong to two different Geo clusters.
5	Optional parameter. Enables booth authentication for clients and servers on the basis of a shared key. This parameter specifies the path to the key file. Use different key files for different tenants. Key Requirements # The key can be either binary or text. If it is text, the following characters are ignored: leading and trailing white space, new lines. The key must be between 8 and 64 characters long. The key must belong to the user `hacluster` and the group `haclient`. The key must be readable only by the file owner.
6	The tickets to be managed by booth or a cluster administrator. Theoretically the same ticket names can be defined in different booth configuration files—the tickets will not interfere because they are part of different Geo clusters that are managed by different booth instances. However, (for better overview) we advise to use distinct ticket names for each Geo cluster as shown in the examples above.
12	Optional parameter. If set, the specified command is called before `boothd` tries to acquire or renew a ticket. On exit code other than `0`, `boothd` relinquishes the ticket.
13	The `service-runnable` script referenced here is included in the product as an example. It is a simple script based on `crm_simulate`. It can be used to test whether a particular cluster resource can be run on the current cluster site. That means, it checks if the cluster is healthy enough to run the resource (all resource dependencies are fulfilled, the cluster partition has quorum, no dirty nodes, etc.). For example, if a service in the dependency chain has a fail count of `INFINITY` on all available nodes, the service cannot be run on that site. In that case, it is of no use to claim the ticket.
14	The resource to be tested by the `before-acquire-handler` (in this case, by the `service-runnable` script). You need to reference the resource that is protected by the respective ticket.

Procedura 4.1: Using the same arbitrator for different Geo clusters #

Create different booth configuration files in /etc/booth as shown in Esempio 4.2, «/etc/booth/apac.conf» and Esempio 4.3, «/etc/booth/emea.conf». Do so either manually or with YaST, as outlined in Sezione 4.3.2, «Setting up booth with YaST».
On the arbitrator, open the ports that are defined in any of the booth configuration files in /etc/booth.
On the nodes belonging to the individual Geo clusters that the arbitrator is used for, open the port that is used for the respective booth instance.
Synchronize the respective booth configuration files across all cluster nodes and arbitrators that use the same booth configuration. For details, see Sezione 4.5, «Synchronizing the booth configuration to all sites and arbitrators».
On the arbitrator, start the individual booth instances as described in Starting the booth services on arbitrators for multi-tenancy setups.
On the individual Geo clusters, start the booth service as described in Starting the booth services on cluster sites.

4.5 Synchronizing the booth configuration to all sites and arbitrators #

Nota: Use the same booth configuration on all sites and arbitrators

To make booth work correctly, all cluster nodes and arbitrators within one Geo cluster must use the same booth configuration.

You can use Csync2 to synchronize the booth configuration. For details, see Sezione 5.1, «Csync2 setup for Geo clusters» and Sezione 5.2, «Synchronizing changes with Csync2».

In case of any booth configuration changes, make sure to update the configuration files accordingly on all parties and to restart the booth services as described in Sezione 4.7, «Reconfiguring booth while running».

4.6 Enabling and starting the booth services #

Starting the booth services on cluster sites

The booth service for each cluster site is managed by the booth resource group (that has either been configured automatically if you used the bootstrap scripts for Geo cluster setup, or manually as described in Sezione 6.2, «Configuring a resource group for boothd»). To start one instance of the booth service per site, start the respective booth resource group on each cluster site.

Starting the booth services on arbitrators

Starting with SUSE Linux Enterprise 12, booth arbitrators are managed with systemd. The unit file is named booth@.service. The @ denotes the possibility to run the service with a parameter, which is, in this case, the name of the configuration file.

To enable the booth service on an arbitrator, use the following command:

# systemctl enable booth@booth

After the service has been enabled from command line, YaST Services Manager can be used to manage the service (as long as the service is not disabled). In that case, it disappears from the service list in YaST the next time systemd is restarted.

The command to start the booth service depends on your booth setup:

If you are using the default setup as described in Sezione 4.3, only /etc/booth/booth.conf is configured. In that case, log in to each arbitrator and use the following command:
```
# systemctl start booth@booth
```
If you are running booth in multi-tenancy mode as described in Sezione 4.4, you have configured multiple booth configuration files in /etc/booth. To start the services for the individual booth instances, use systemctl start booth@NAME, where NAME stands for the name of the respective configuration file /etc/booth/NAME.conf.
For example, if you have the booth configuration files /etc/booth/emea.conf and /etc/booth/apac.conf, log in to your arbitrator and execute the following commands:
```
# systemctl start booth@emea
# systemctl start booth@apac
```

This starts the booth service in arbitrator mode. It can communicate with all other booth daemons but in contrast to the booth daemons running on the cluster sites, it cannot be granted a ticket. Booth arbitrators take part in elections only. Otherwise, they are dormant.

4.7 Reconfiguring booth while running #

In case you need to change the booth configuration while the booth services are already running, proceed as follows:

Adjust the booth configuration files as desired.
Synchronize the updated booth configuration files to all cluster nodes and arbitrators that are part of your Geo cluster. For details, see Capitolo 5, Synchronizing configuration files across all sites and arbitrators.
Restart the booth services on the arbitrators and cluster sites as described in Sezione 4.6, «Enabling and starting the booth services». This does not have any effect on tickets that have already been granted to sites.