diff --git a/doc/sphinx/Clusters_from_Scratch/cluster-setup.rst b/doc/sphinx/Clusters_from_Scratch/cluster-setup.rst index 67ff69d97f..ced433a6a0 100644 --- a/doc/sphinx/Clusters_from_Scratch/cluster-setup.rst +++ b/doc/sphinx/Clusters_from_Scratch/cluster-setup.rst @@ -1,309 +1,309 @@ Set up a Cluster ---------------- Simplify Administration With a Cluster Shell ############################################ In the dark past, configuring Pacemaker required the administrator to read and write XML. In true UNIX style, there were also a number of different commands that specialized in different aspects of querying and updating the cluster. In addition, the various components of the cluster stack (corosync, pacemaker, etc.) had to be configured separately, with different configuration tools and formats. All of that has been greatly simplified with the creation of higher-level tools, whether command-line or GUIs, that hide all the mess underneath. Command-line cluster shells take all the individual aspects required for managing and configuring a cluster, and pack them into one simple-to-use command-line tool. They even allow you to queue up several changes at once and commit them all at once. Two popular command-line shells are ``pcs`` and ``crmsh``. Clusters from Scratch is -based on ``pcs`` because it comes with CentOS, but both have similar +based on ``pcs`` because it comes with |CFS_DISTRO|, but both have similar functionality. Choosing a shell or GUI is a matter of personal preference and what comes with (and perhaps is supported by) your choice of operating system. Install the Cluster Software ############################ Fire up a shell on both nodes and run the following to activate the High Availability repo. .. code-block:: none # dnf config-manager --set-enabled ha .. IMPORTANT:: This document will show commands that need to be executed on both nodes with a simple ``#`` prompt. Be sure to run them on each node individually. Now, we'll install pacemaker, pcs, and some other command-line tools that will make our lives easier: .. code-block:: none # dnf install -y pacemaker pcs psmisc policycoreutils-python3 .. NOTE:: This document uses ``pcs`` for cluster management. Other alternatives, such as ``crmsh``, are available, but their syntax will differ from the examples used here. Configure the Cluster Software ############################## .. index:: single: firewall Allow cluster services through firewall _______________________________________ On each node, allow cluster-related services through the local firewall: .. code-block:: none # firewall-cmd --permanent --add-service=high-availability success # firewall-cmd --reload success .. NOTE :: If you are using iptables directly, or some other firewall solution besides firewalld, simply open the following ports, which can be used by various clustering components: TCP ports 2224, 3121, and 21064, and UDP port 5405. If you run into any problems during testing, you might want to disable the firewall and SELinux entirely until you have everything working. This may create significant security issues and should not be performed on machines that will be exposed to the outside world, but may be appropriate during development and testing on a protected host. To disable security measures: .. code-block:: none [root@pcmk-1 ~]# setenforce 0 [root@pcmk-1 ~]# sed -i.bak "s/SELINUX=enforcing/SELINUX=permissive/g" /etc/selinux/config [root@pcmk-1 ~]# systemctl mask firewalld.service [root@pcmk-1 ~]# systemctl stop firewalld.service [root@pcmk-1 ~]# iptables --flush Enable pcs Daemon _________________ Before the cluster can be configured, the pcs daemon must be started and enabled to start at boot time on each node. This daemon works with the pcs command-line interface to manage synchronizing the corosync configuration across all nodes in the cluster, among other functions. Start and enable the daemon by issuing the following commands on each node: .. code-block:: none # systemctl start pcsd.service # systemctl enable pcsd.service Created symlink from /etc/systemd/system/multi-user.target.wants/pcsd.service to /usr/lib/systemd/system/pcsd.service. The installed packages will create an **hacluster** user with a disabled password. While this is fine for running ``pcs`` commands locally, the account needs a login password in order to perform such tasks as syncing the corosync configuration, or starting and stopping the cluster on other nodes. This tutorial will make use of such commands, so now we will set a password for the **hacluster** user, using the same password on both nodes: .. code-block:: none # passwd hacluster Changing password for user hacluster. New password: Retype new password: passwd: all authentication tokens updated successfully. .. NOTE:: Alternatively, to script this process or set the password on a different machine from the one you're logged into, you can use the ``--stdin`` option for ``passwd``: .. code-block:: none [root@pcmk-1 ~]# ssh pcmk-2 -- 'echo mysupersecretpassword | passwd --stdin hacluster' Configure Corosync __________________ On either node, use ``pcs host auth`` to authenticate as the **hacluster** user: .. code-block:: none [root@pcmk-1 ~]# pcs host auth pcmk-1 pcmk-2 Username: hacluster Password: pcmk-2: Authorized pcmk-1: Authorized Next, use ``pcs cluster setup`` on the same node to generate and synchronize the corosync configuration: .. code-block:: none [root@pcmk-1 ~]# pcs cluster setup mycluster pcmk-1 pcmk-2 No addresses specified for host 'pcmk-1', using 'pcmk-1' No addresses specified for host 'pcmk-2', using 'pcmk-2' Destroying cluster on hosts: 'pcmk-1', 'pcmk-2'... pcmk-2: Successfully destroyed cluster pcmk-1: Successfully destroyed cluster Requesting remove 'pcsd settings' from 'pcmk-1', 'pcmk-2' pcmk-1: successful removal of the file 'pcsd settings' pcmk-2: successful removal of the file 'pcsd settings' Sending 'corosync authkey', 'pacemaker authkey' to 'pcmk-1', 'pcmk-2' pcmk-1: successful distribution of the file 'corosync authkey' pcmk-1: successful distribution of the file 'pacemaker authkey' pcmk-2: successful distribution of the file 'corosync authkey' pcmk-2: successful distribution of the file 'pacemaker authkey' Sending 'corosync.conf' to 'pcmk-1', 'pcmk-2' pcmk-1: successful distribution of the file 'corosync.conf' pcmk-2: successful distribution of the file 'corosync.conf' Cluster has been successfully set up. .. NOTE:: If you'd like, you can specify an **addr** option for each node in the ``pcs cluster setup`` command. This will create an explicit name-to-address mapping for each node in ``/etc/corosync/corosync.conf``, eliminating the need for hostname resolution via DNS, ``/etc/hosts``, and the like. .. code-block:: none [root@pcmk-1 ~]# pcs cluster setup mycluster \ pcmk-1 addr=192.168.122.101 pcmk-2 addr=192.168.122.102 If you received an authorization error for either of those commands, make sure you configured the **hacluster** user account on each node with the same password. The final corosync.conf configuration on each node should look something like the sample in :ref:`sample-corosync-configuration`. Explore pcs ########### Start by taking some time to familiarize yourself with what ``pcs`` can do. .. code-block:: none [root@pcmk-1 ~]# pcs Usage: pcs [-f file] [-h] [commands]... Control and configure pacemaker and corosync. Options: -h, --help Display usage and exit. -f file Perform actions on file instead of active CIB. Commands supporting the option use the initial state of the specified file as their input and then overwrite the file with the state reflecting the requested operation(s). A few commands only use the specified file in read-only mode since their effect is not a CIB modification. --debug Print all network traffic and external commands run. --version Print pcs version information. List pcs capabilities if --full is specified. --request-timeout Timeout for each outgoing request to another node in seconds. Default is 60s. --force Override checks and errors, the exact behavior depends on the command. WARNING: Using the --force option is strongly discouraged unless you know what you are doing. Commands: cluster Configure cluster options and nodes. resource Manage cluster resources. stonith Manage fence devices. constraint Manage resource constraints. property Manage pacemaker properties. acl Manage pacemaker access control lists. qdevice Manage quorum device provider on the local host. quorum Manage cluster quorum settings. booth Manage booth (cluster ticket manager). status View cluster status. config View and manage cluster configuration. pcsd Manage pcs daemon. host Manage hosts known to pcs/pcsd. node Manage cluster nodes. alert Manage pacemaker alerts. client Manage pcsd client configuration. dr Manage disaster recovery configuration. tag Manage pacemaker tags. As you can see, the different aspects of cluster management are separated into categories. To discover the functionality available in each of these categories, one can issue the command ``pcs help``. Below is an example of all the options available under the status category. .. code-block:: none [root@pcmk-1 ~]# pcs status help Usage: pcs status [commands]... View current cluster and resource status Commands: [status] [--full] [--hide-inactive] View all information about the cluster and resources (--full provides more details, --hide-inactive hides inactive resources). resources [--hide-inactive] Show status of all currently configured resources. If --hide-inactive is specified, only show active resources. cluster View current cluster status. corosync View current membership information as seen by corosync. quorum View current quorum status. qdevice [--full] [] Show runtime status of specified model of quorum device provider. Using --full will give more detailed output. If is specified, only information about the specified cluster will be displayed. booth Print current status of booth on the local node. nodes [corosync | both | config] View current status of nodes from pacemaker. If 'corosync' is specified, view current status of nodes from corosync instead. If 'both' is specified, view current status of nodes from both corosync & pacemaker. If 'config' is specified, print nodes from corosync & pacemaker configuration. pcsd []... Show current status of pcsd on nodes specified, or on all nodes configured in the local cluster if no nodes are specified. xml View xml version of status (output from crm_mon -r -1 -X). Additionally, if you are interested in the version and supported cluster stack(s) available with your Pacemaker installation, run: .. code-block:: none [root@pcmk-1 ~]# pacemakerd --features Pacemaker 2.0.5-4.el8 (Build: ba59be7122) Supporting v3.6.1: generated-manpages agent-manpages ncurses libqb-logging libqb-ipc systemd nagios corosync-native atomic-attrd acls cibsecrets diff --git a/doc/sphinx/Clusters_from_Scratch/shared-storage.rst b/doc/sphinx/Clusters_from_Scratch/shared-storage.rst index 90948bc9ad..56d0cf85c7 100644 --- a/doc/sphinx/Clusters_from_Scratch/shared-storage.rst +++ b/doc/sphinx/Clusters_from_Scratch/shared-storage.rst @@ -1,621 +1,621 @@ .. index:: pair: storage; DRBD Replicate Storage Using DRBD ---------------------------- Even if you're serving up static websites, having to manually synchronize the contents of that website to all the machines in the cluster is not ideal. For dynamic websites, such as a wiki, it's not even an option. Not everyone can afford network-attached storage, but somehow the data needs to be kept in sync. Enter DRBD, which can be thought of as network-based RAID-1 [#]_. Install the DRBD Packages ######################### DRBD itself is included in the upstream kernel [#]_, but we do need some utilities to use it effectively. -CentOS does not ship these utilities, so we need to enable a third-party +|CFS_DISTRO| does not ship these utilities, so we need to enable a third-party repository to get them. Supported packages for many OSes are available from DRBD's maker `LINBIT `_, but here we'll use the free `ELRepo `_ repository. On both nodes, import the ELRepo package signing key, and enable the repository: .. code-block:: none # rpm --import https://www.elrepo.org/RPM-GPG-KEY-elrepo.org # rpm -Uvh https://www.elrepo.org/elrepo-release-8.el8.elrepo.noarch.rpm Retrieving https://www.elrepo.org/elrepo-release-8.el8.elrepo.noarch.rpm Verifying... ################################# [100%] Preparing... ################################# [100%] Updating / installing... 1:elrepo-release-8.2-1.el8.elrepo ################################# [100%] Now, we can install the DRBD kernel module and utilities: .. code-block:: none # dnf install -y kmod-drbd90 drbd90-utils DRBD will not be able to run under the default SELinux security policies. If you are familiar with SELinux, you can modify the policies in a more fine-grained manner, but here we will simply exempt DRBD processes from SELinux control: .. code-block:: none # dnf install -y policycoreutils-python-utils # semanage permissive -a drbd_t We will configure DRBD to use port 7789, so allow that port from each host to the other: .. code-block:: none [root@pcmk-1 ~]# firewall-cmd --permanent --add-rich-rule='rule family="ipv4" \ source address="192.168.122.102" port port="7789" protocol="tcp" accept' success [root@pcmk-1 ~]# firewall-cmd --reload success .. code-block:: none [root@pcmk-2 ~]# firewall-cmd --permanent --add-rich-rule='rule family="ipv4" \ source address="192.168.122.101" port port="7789" protocol="tcp" accept' success [root@pcmk-2 ~]# firewall-cmd --reload success .. NOTE:: In this example, we have only two nodes, and all network traffic is on the same LAN. In production, it is recommended to use a dedicated, isolated network for cluster-related traffic, so the firewall configuration would likely be different; one approach would be to add the dedicated network interfaces to the trusted zone. .. NOTE:: If the ``firewall-cmd --add-rich-rule`` command fails with **Error: INVALID_RULE: unknown element**, ensure that there is no space at the beginning of the second line of the command. Allocate a Disk Volume for DRBD ############################### DRBD will need its own block device on each node. This can be a physical disk partition or logical volume, of whatever size you need for your data. For this document, we will use a 512MiB logical volume, which is more than sufficient for a single HTML file and (later) GFS2 metadata. .. code-block:: none [root@pcmk-1 ~]# vgdisplay | grep -e Name -e Free VG Name cs_pcmk-1 Free PE / Size 3583 / <14.00 GiB [root@pcmk-1 ~]# lvcreate --name drbd-demo --size 512M cs_pcmk-1 Logical volume "drbd-demo" created. [root@pcmk-1 ~]# lvs LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert drbd-demo centos_pcmk-1 -wi-a----- 512.00m root centos_pcmk-1 -wi-ao---- 3.00g swap centos_pcmk-1 -wi-ao---- 1.00g Repeat for the second node, making sure to use the same size: .. code-block:: none [root@pcmk-1 ~]# ssh pcmk-2 -- lvcreate --name drbd-demo --size 512M cs_pcmk-2 Logical volume "drbd-demo" created. Configure DRBD ############## There is no series of commands for building a DRBD configuration, so simply run this on both nodes to use this sample configuration: .. code-block:: none # cat </etc/drbd.d/wwwdata.res resource wwwdata { protocol C; meta-disk internal; device /dev/drbd1; syncer { verify-alg sha1; } net { allow-two-primaries; } on pcmk-1 { disk /dev/cs_pcmk-1/drbd-demo; address 192.168.122.101:7789; } on pcmk-2 { disk /dev/cs_pcmk-2/drbd-demo; address 192.168.122.102:7789; } } END .. IMPORTANT:: Edit the file to use the hostnames, IP addresses, and logical volume paths of your nodes if they differ from the ones used in this guide. .. NOTE:: Detailed information on the directives used in this configuration (and other alternatives) is available in the `DRBD User's Guide `_. The **allow-two-primaries** option would not normally be used in an active/passive cluster. We are adding it here for the convenience of changing to an active/active cluster later. Initialize DRBD ############### With the configuration in place, we can now get DRBD running. These commands create the local metadata for the DRBD resource, ensure the DRBD kernel module is loaded, and bring up the DRBD resource. Run them on one node: .. code-block:: none [root@pcmk-1 ~]# drbdadm create-md wwwdata initializing activity log initializing bitmap (16 KB) to all zero Writing meta data... New drbd meta data block successfully created. [root@pcmk-1 ~]# modprobe drbd [root@pcmk-1 ~]# drbdadm up wwwdata --== Thank you for participating in the global usage survey ==-- The server's response is: you are the 801th user to install this version We can confirm DRBD's status on this node: .. code-block:: none [root@pcmk-1 ~]# drbdadm status wwwdata role:Secondary disk:Inconsistent pcmk-2 connection:Connecting Because we have not yet initialized the data, this node's data is marked as **Inconsistent**. Because we have not yet initialized the second node, the pcmk-2 connection is **Connecting** (waiting for connection). Now, repeat the above commands on the second node, starting with creating wwwdata.res. After giving it time to connect, when we check the status of the first node, it shows: .. code-block:: none [root@pcmk-1 ~]# drbdadm status wwwdata role:Secondary disk:Inconsistent pcmk-2 role:Secondary peer-disk:Inconsistent You can see that **pcmk-2 connection:Connecting** longer appears in the output, meaning the two DRBD nodes are communicating properly, and both nodes are in **Secondary** role with **Inconsistent** data. To make the data consistent, we need to tell DRBD which node should be considered to have the correct data. In this case, since we are creating a new resource, both have garbage, so we'll just pick pcmk-1 and run this command on it: .. code-block:: none [root@pcmk-1 ~]# drbdadm primary --force wwwdata .. NOTE:: If you are using a different version of DRBD, the required syntax may be different. See the documentation for your version for how to perform these commands. If we check the status of both nodes immediately, we'll see something like this: .. code-block:: none [root@pcmk-1 ~]# drbdadm status wwwdata role:Primary disk:UpToDate pcmk-1 role:Secondary peer-disk:UpToDate [root@pcmk-2 ~]# drbdadm status wwwdata role:Secondary disk:UpToDate pcmk-1 role:Primary peer-disk:Inconsistent We can see that the first node has the **Primary** role, its partner node has the **Secondary** role, the first node's data is now considered **UpToDate**, the partner node's data is still **Inconsistent**. After a while, the sync should finish, and you'll see something like: .. code-block:: none [root@pcmk-1 ~]# drbdadm status wwwdata role:Primary disk:UpToDate pcmk-1 role:Secondary peer-disk:UpToDate [root@pcmk-2 ~]# drbdadm status wwwdata role:Secondary disk:UpToDate pcmk-1 role:Primary peer-disk:UpToDate Both sets of data are now **UpToDate**, and we can proceed to creating and populating a filesystem for our WebSite resource's documents. Populate the DRBD Disk ###################### On the node with the primary role (pcmk-1 in this example), create a filesystem on the DRBD device: .. code-block:: none [root@pcmk-1 ~]# mkfs.xfs /dev/drbd1 meta-data=/dev/drbd1 isize=512 agcount=4, agsize=32765 blks = sectsz=512 attr=2, projid32bit=1 = crc=1 finobt=1, sparse=1, rmapbt=0 = reflink=1 data = bsize=4096 blocks=131059, imaxpct=25 = sunit=0 swidth=0 blks naming =version 2 bsize=4096 ascii-ci=0, ftype=1 log =internal log bsize=4096 blocks=1368, version=2 = sectsz=512 sunit=0 blks, lazy-count=1 realtime =none extsz=4096 blocks=0, rtextents=0 Discarding blocks...Done. .. NOTE:: In this example, we create an xfs filesystem with no special options. In a production environment, you should choose a filesystem type and options that are suitable for your application. Mount the newly created filesystem, populate it with our web document, give it the same SELinux policy as the web document root, then unmount it (the cluster will handle mounting and unmounting it later): .. code-block:: none [root@pcmk-1 ~]# mount /dev/drbd1 /mnt [root@pcmk-1 ~]# cat <<-END >/mnt/index.html My Test Site - DRBD END [root@pcmk-1 ~]# chcon -R --reference=/var/www/html /mnt [root@pcmk-1 ~]# umount /dev/drbd1 Configure the Cluster for the DRBD device ######################################### One handy feature ``pcs`` has is the ability to queue up several changes into a file and commit those changes all at once. To do this, start by populating the file with the current raw XML config from the CIB. .. code-block:: none [root@pcmk-1 ~]# pcs cluster cib drbd_cfg Using pcs's ``-f`` option, make changes to the configuration saved in the ``drbd_cfg`` file. These changes will not be seen by the cluster until the ``drbd_cfg`` file is pushed into the live cluster's CIB later. Here, we create a cluster resource for the DRBD device, and an additional *clone* resource to allow the resource to run on both nodes at the same time. .. code-block:: none [root@pcmk-1 ~]# pcs -f drbd_cfg resource create WebData ocf:linbit:drbd \ drbd_resource=wwwdata op monitor interval=60s [root@pcmk-1 ~]# pcs -f drbd_cfg resource promotable WebData \ promoted-max=1 promoted-node-max=1 clone-max=2 clone-node-max=1 \ notify=true [root@pcmk-1 ~]# pcs resource status * ClusterIP (ocf::heartbeat:IPaddr2): Started pcmk-1 * WebSite (ocf::heartbeat:apache): Started pcmk-1 [root@pcmk-1 ~]# pcs resource config Resource: ClusterIP (class=ocf provider=heartbeat type=IPaddr2) Attributes: cidr_netmask=24 ip=192.168.122.120 Operations: monitor interval=30s (ClusterIP-monitor-interval-30s) start interval=0s timeout=20s (ClusterIP-start-interval-0s) stop interval=0s timeout=20s (ClusterIP-stop-interval-0s) Resource: WebSite (class=ocf provider=heartbeat type=apache) Attributes: configfile=/etc/httpd/conf/httpd.conf statusurl=http://localhost/server-status Operations: monitor interval=1min (WebSite-monitor-interval-1min) start interval=0s timeout=40s (WebSite-start-interval-0s) stop interval=0s timeout=60s (WebSite-stop-interval-0s) After you are satisfied with all the changes, you can commit them all at once by pushing the drbd_cfg file into the live CIB. .. code-block:: none [root@pcmk-1 ~]# pcs cluster cib-push drbd_cfg --config CIB updated Let's see what the cluster did with the new configuration: .. code-block:: none [root@pcmk-1 ~]# pcs status Cluster name: mycluster Cluster Summary: * Stack: corosync * Current DC: pcmk-1 (version 2.0.5-4.el8-ba59be7122) - partition with quorum * Last updated: Wed Feb 3 09:04:23 2021 * Last change: Wed Feb 3 09:04:18 2021 by root via cibadmin on pcmk-1 * 2 nodes configured * 4 resource instances configured Node List: * Online: [ pcmk-1 pcmk-2 ] Full List of Resources: * ClusterIP (ocf::heartbeat:IPaddr2): Started pcmk-1 * WebSite (ocf::heartbeat:apache): Started pcmk-1 * Clone Set: WebData-clone [WebData] (promotable): * Masters: [ pcmk-1 ] * Slaves: [ pcmk-2 ] Daemon Status: corosync: active/disabled pacemaker: active/disabled pcsd: active/enabled We can see that **WebData-clone** (our DRBD device) is running as promoted (DRBD's primary role) on **pcmk-1** and unpromoted (DRBD's secondary role) on **pcmk-2**. .. IMPORTANT:: The resource agent should load the DRBD module when needed if it's not already loaded. If that does not happen, configure your operating system to load the module at boot time. For |CFS_DISTRO| |CFS_DISTRO_VER|, you would run this on both nodes: .. code-block:: none # echo drbd >/etc/modules-load.d/drbd.conf Configure the Cluster for the Filesystem ######################################## Now that we have a working DRBD device, we need to mount its filesystem. In addition to defining the filesystem, we also need to tell the cluster where it can be located (only on the DRBD Primary) and when it is allowed to start (after the Primary was promoted). We are going to take a shortcut when creating the resource this time. Instead of explicitly saying we want the **ocf:heartbeat:Filesystem** script, we are only going to ask for **Filesystem**. We can do this because we know there is only one resource script named **Filesystem** available to pacemaker, and that pcs is smart enough to fill in the **ocf:heartbeat:** portion for us correctly in the configuration. If there were multiple **Filesystem** scripts from different OCF providers, we would need to specify the exact one we wanted. Once again, we will queue our changes to a file and then push the new configuration to the cluster as the final step. .. code-block:: none [root@pcmk-1 ~]# pcs cluster cib fs_cfg [root@pcmk-1 ~]# pcs -f fs_cfg resource create WebFS Filesystem \ device="/dev/drbd1" directory="/var/www/html" fstype="xfs" Assumed agent name 'ocf:heartbeat:Filesystem' (deduced from 'Filesystem') [root@pcmk-1 ~]# pcs -f fs_cfg constraint colocation add \ WebFS with WebData-clone INFINITY with-rsc-role=Master [root@pcmk-1 ~]# pcs -f fs_cfg constraint order \ promote WebData-clone then start WebFS Adding WebData-clone WebFS (kind: Mandatory) (Options: first-action=promote then-action=start) We also need to tell the cluster that Apache needs to run on the same machine as the filesystem and that it must be active before Apache can start. .. code-block:: none [root@pcmk-1 ~]# pcs -f fs_cfg constraint colocation add WebSite with WebFS INFINITY [root@pcmk-1 ~]# pcs -f fs_cfg constraint order WebFS then WebSite Adding WebFS WebSite (kind: Mandatory) (Options: first-action=start then-action=start) Review the updated configuration. .. code-block:: none [root@pcmk-1 ~]# pcs -f fs_cfg constraint Location Constraints: Resource: WebSite Enabled on: Node: pcmk-1 (score:50) Ordering Constraints: start ClusterIP then start WebSite (kind:Mandatory) promote WebData-clone then start WebFS (kind:Mandatory) start WebFS then start WebSite (kind:Mandatory) Colocation Constraints: WebSite with ClusterIP (score:INFINITY) WebFS with WebData-clone (score:INFINITY) (with-rsc-role:Master) WebSite with WebFS (score:INFINITY) Ticket Constraints: [root@pcmk-1 ~]# pcs resource status * ClusterIP (ocf::heartbeat:IPaddr2): Started pcmk-1 * WebSite (ocf::heartbeat:apache): Started pcmk-1 * Clone Set: WebData-clone [WebData] (promotable): * Masters: [ pcmk-1 ] * Slaves: [ pcmk-2 ] [root@pcmk-1 ~]# pcs resource config Resource: ClusterIP (class=ocf provider=heartbeat type=IPaddr2) Attributes: cidr_netmask=24 ip=192.168.122.120 Operations: monitor interval=30s (ClusterIP-monitor-interval-30s) start interval=0s timeout=20s (ClusterIP-start-interval-0s) stop interval=0s timeout=20s (ClusterIP-stop-interval-0s) Resource: WebSite (class=ocf provider=heartbeat type=apache) Attributes: configfile=/etc/httpd/conf/httpd.conf statusurl=http://localhost/server-status Operations: monitor interval=1min (WebSite-monitor-interval-1min) start interval=0s timeout=40s (WebSite-start-interval-0s) stop interval=0s timeout=60s (WebSite-stop-interval-0s) Clone: WebData-clone Meta Attrs: clone-max=2 clone-node-max=1 notify=true promotable=true promoted-max=1 promoted-node-max=1 Resource: WebData (class=ocf provider=linbit type=drbd) Attributes: drbd_resource=wwwdata Operations: demote interval=0s timeout=90 (WebData-demote-interval-0s) monitor interval=60s (WebData-monitor-interval-60s) notify interval=0s timeout=90 (WebData-notify-interval-0s) promote interval=0s timeout=90 (WebData-promote-interval-0s) reload interval=0s timeout=30 (WebData-reload-interval-0s) start interval=0s timeout=240 (WebData-start-interval-0s) stop interval=0s timeout=100 (WebData-stop-interval-0s) After reviewing the new configuration, upload it and watch the cluster put it into effect. .. code-block:: none [root@pcmk-1 ~]# pcs cluster cib-push fs_cfg --config CIB updated [root@pcmk-1 ~]# pcs status Cluster name: mycluster Cluster Summary: * Stack: corosync * Current DC: pcmk-1 (version 2.0.5-4.el8-ba59be7122) - partition with quorum * Last updated: Wed Feb 3 09:17:24 2021 * Last change: Wed Feb 3 09:17:19 2021 by root via cibadmin on pcmk-1 * 2 nodes configured * 5 resource instances configured Node List: * Online: [ pcmk-1 pcmk-2 ] Full List of Resources: * ClusterIP (ocf::heartbeat:IPaddr2): Started pcmk-1 * WebSite (ocf::heartbeat:apache): Started pcmk-1 * Clone Set: WebData-clone [WebData] (promotable): * Masters: [ pcmk-1 ] * Slaves: [ pcmk-2 ] * WebFS (ocf::heartbeat:Filesystem): Started pcmk-1 Daemon Status: corosync: active/disabled pacemaker: active/disabled pcsd: active/enabled Test Cluster Failover ##################### Previously, we used ``pcs cluster stop pcmk-1`` to stop all cluster services on **pcmk-1**, failing over the cluster resources, but there is another way to safely simulate node failure. We can put the node into *standby mode*. Nodes in this state continue to run corosync and pacemaker but are not allowed to run resources. Any resources found active there will be moved elsewhere. This feature can be particularly useful when performing system administration tasks such as updating packages used by cluster resources. Put the active node into standby mode, and observe the cluster move all the resources to the other node. The node's status will change to indicate that it can no longer host resources, and eventually all the resources will move. .. code-block:: none [root@pcmk-1 ~]# pcs node standby pcmk-1 [root@pcmk-1 ~]# pcs status Cluster name: mycluster Cluster Summary: * Stack: corosync * Current DC: pcmk-1 (version 2.0.5-4.el8-ba59be7122) - partition with quorum * Last updated: Wed Feb 3 09:18:45 2021 * Last change: Wed Feb 3 09:18:35 2021 by root via cibadmin on pcmk-1 * 2 nodes configured * 5 resource instances configured Node List: * Node pcmk-1: standby * Online: [ pcmk-2 ] Full List of Resources: * ClusterIP (ocf::heartbeat:IPaddr2): Started pcmk-2 * WebSite (ocf::heartbeat:apache): Started pcmk-2 * Clone Set: WebData-clone [WebData] (promotable): * Masters: [ pcmk-2 ] * Stopped: [ pcmk-1 ] * WebFS (ocf::heartbeat:Filesystem): Started pcmk-2 Daemon Status: corosync: active/disabled pacemaker: active/disabled pcsd: active/enabled Once we've done everything we needed to on pcmk-1 (in this case nothing, we just wanted to see the resources move), we can unstandby the node, making it eligible to host resources again. .. code-block:: none [root@pcmk-1 ~]# pcs node unstandby pcmk-1 [root@pcmk-1 ~]# pcs status Cluster name: mycluster Cluster Summary: * Stack: corosync * Current DC: pcmk-1 (version 2.0.5-4.el8-ba59be7122) - partition with quorum * Last updated: Wed Feb 3 09:19:47 2021 * Last change: Wed Feb 3 09:19:29 2021 by root via cibadmin on pcmk-1 * 2 nodes configured * 5 resource instances configured Node List: * Online: [ pcmk-1 pcmk-2 ] Full List of Resources: * ClusterIP (ocf::heartbeat:IPaddr2): Started pcmk-1 * WebSite (ocf::heartbeat:apache): Started pcmk-1 * Clone Set: WebData-clone [WebData] (promotable): * Masters: [ pcmk-1 ] * Slaves: [ pcmk-2 ] * WebFS (ocf::heartbeat:Filesystem): Started pcmk-1 Daemon Status: corosync: active/disabled pacemaker: active/disabled pcsd: active/enabled Notice that **pcmk-1** is back to the **Online** state, and that the cluster resources stay where they are due to our resource stickiness settings configured earlier. .. [#] See http://www.drbd.org for details. .. [#] Since version 2.6.33