Red Hat Enterprise Linux 8 Configuring and managing high availability clusters Configuring and managing the Red Hat High Availability Add-On Last Updated: 2021-09-23 Red Hat Enterprise Linux 8 Configuring and managing high availability clusters Configuring and managing the Red Hat High Availability Add-On Legal Notice Copyright © 2021 Red Hat, Inc. The text of and illustrations in this document are licensed by Red Hat under a Creative Commons Attribution–Share Alike 3.0 Unported license ("CC-BY-SA"). An explanation of CC-BY-SA is available at http://creativecommons.org/licenses/by-sa/3.0/ . In accordance with CC-BY-SA, if you distribute this document or an adaptation of it, you must provide the URL for the original version. Red Hat, as the licensor of this document, waives the right to enforce, and agrees not to assert, Section 4d of CC-BY-SA to the fullest extent permitted by applicable law. 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The OpenStack ® Word Mark and OpenStack logo are either registered trademarks/service marks or trademarks/service marks of the OpenStack Foundation, in the United States and other countries and are used with the OpenStack Foundation's permission. We are not affiliated with, endorsed or sponsored by the OpenStack Foundation, or the OpenStack community. All other trademarks are the property of their respective owners. Abstract This guide provides information about installing, configuring, and managing the Red Hat High Availability Add-On for Red Hat Enterprise Linux 8. Table of Contents Table of Contents .M . A. .K . I.N . .G . .O . P. .E . N. S. .O . U. .R . C. .E . .M . .O . R. .E . .I N. .C . L. .U . S. .I V. .E . 8. .P .R . O. V. .I D. .I N. .G . F. .E .E . D. .B . A. .C . K. O. .N . R. .E .D . .H . .A .T . .D . O. C. .U . M. E. .N . T. .A .T . I.O . .N . 9. .C . H. .A . P. .T .E . R. 1.. .H . .I G. .H . .A . V. .A . I.L . A. .B . I.L . I.T . Y. A. .D . D. .- .O . N. .O . V. .E . R. .V . I.E .W . 1.0 . 1.1. HIGH AVAILABILITY ADD-ON COMPONENTS 10 1.2. HIGH AVAILABILITY ADD-ON CONCEPTS 10 1.2.1. Fencing 10 1.2.2. Quorum 11 1.2.3. Cluster resources 11 1.3. PACEMAKER OVERVIEW 12 1.3.1. Pacemaker architecture components 12 1.3.2. Pacemaker configuration and management tools 13 1.3.3. The cluster and pacemaker configuration files 13 1.4. LVM LOGICAL VOLUMES IN A RED HAT HIGH AVAILABILITY CLUSTER 13 1.4.1. Choosing HA-LVM or shared volumes 13 1.4.2. Configuring LVM volumes in a cluster 14 .C . H. .A . P. .T .E . R. 2. G. E. T. .T . I.N . G. .S .T . A. .R . T. .E .D . W. I.T .H . P. .A .C . .E .M . .A . K. .E . R. 1. 5. 2.1. LEARNING TO USE PACEMAKER 15 2.2. LEARNING TO CONFIGURE FAILOVER 19 .C . H. .A . P. .T .E . R. 3. T. .H . E. P. .C . S. C. .O . M. M. A. .N . D. L. .I N. .E . .I N. .T . E. .R . F. A. .C . E. .2 . 4. 3.1. PCS HELP DISPLAY 24 3.2. VIEWING THE RAW CLUSTER CONFIGURATION 24 3.3. SAVING A CONFIGURATION CHANGE TO A WORKING FILE 24 3.4. DISPLAYING CLUSTER STATUS 25 3.5. DISPLAYING THE FULL CLUSTER CONFIGURATION 26 3.6. MODIFYING THE COROSYNC.CONF FILE WITH THE PCS COMMAND (RHEL 8.4 AND LATER) 26 3.7. DISPLAYING THE COROSYNC.CONF FILE WITH THE PCS COMMAND 26 .C . H. .A . P. .T .E . R. 4. .C . R. .E .A . T. .I N. .G . A. R. .E .D . H . .A . T. .H . .I G. .H . -. A. .V . A. .I L. .A . B. .I L. .I T. .Y . .C . L. U. .S . T. .E . R. W . .I .T .H . P . A. .C . E. .M . .A . K. .E .R . .2 . 9. 4.1. INSTALLING CLUSTER SOFTWARE 29 4.2. INSTALLING THE PCP-ZEROCONF PACKAGE (RECOMMENDED) 31 4.3. CREATING A HIGH AVAILABILITY CLUSTER 31 4.4. CREATING A HIGH AVAILABILITY CLUSTER WITH MULTIPLE LINKS 32 4.5. CONFIGURING FENCING 33 4.6. BACKING UP AND RESTORING A CLUSTER CONFIGURATION 34 4.7. ENABLING PORTS FOR THE HIGH AVAILABILITY ADD-ON 35 CHAPTER 5. CONFIGURING AN ACTIVE/PASSIVE APACHE HTTP SERVER IN A RED HAT HIGH .A .V . A. .I .L .A . B. .I L. .I T. .Y . .C . L. .U . S. T. .E . R. .3 . 7. 5.1. CONFIGURING AN LVM VOLUME WITH AN EXT4 FILE SYSTEM IN A PACEMAKER CLUSTER 38 5.2. ENSURING A VOLUME GROUP IS NOT ACTIVATED ON MULTIPLE CLUSTER NODES 39 5.3. CONFIGURING AN APACHE HTTP SERVER 40 5.4. CREATING THE RESOURCES AND RESOURCE GROUPS 42 5.5. TESTING THE RESOURCE CONFIGURATION 43 CHAPTER 6. CONFIGURING AN ACTIVE/PASSIVE NFS SERVER IN A RED HAT HIGH AVAILABILITY .C . L. U. .S . T. .E .R . .4 . 5. 6.1. CONFIGURING AN LVM VOLUME WITH AN EXT4 FILE SYSTEM IN A PACEMAKER CLUSTER 45 6.2. ENSURING A VOLUME GROUP IS NOT ACTIVATED ON MULTIPLE CLUSTER NODES 47 6.3. CONFIGURING AN NFS SHARE 48 1 Red Hat Enterprise Linux 8 Configuring and managing high availability clusters 6.4. CONFIGURING THE RESOURCES AND RESOURCE GROUP FOR AN NFS SERVER IN A CLUSTER 49 6.5. TESTING THE NFS RESOURCE CONFIGURATION 52 6.5.1. Testing the NFS export 52 6.5.2. Testing for failover 53 .C . H. .A . P. .T .E . R. 7. G. F. .S .2 . .F .I .L .E . .S . Y. .S .T . E. .M . S. I.N . A . C . .L .U . S. .T . E. R. .5 . 5. 7.1. CONFIGURING A GFS2 FILE SYSTEM IN A CLUSTER 55 7.2. CONFIGURING AN ENCRYPTED GFS2 FILE SYSTEM IN A CLUSTER (RHEL 8.4 AND LATER) 60 7.2.1. Configure a shared logical volume in a Pacemaker cluster 60 7.2.2. Encrypt the logical volume and create a crypt resource 63 7.2.3. Format the encrypted logical volume with a GFS2 file system and create a file system resource for the cluster. 64 7.3. MIGRATING A GFS2 FILE SYSTEM FROM RHEL7 TO RHEL8 65 .C . H. .A . P. .T .E . R. 8. .G . E. .T .T . I.N . .G . .S . T. A. .R . T. .E . D. W. I.T . H. T. .H . E. .P . C. .S . D. W. E. .B . .U . I. .6 . 7. 8.1. INSTALLING CLUSTER SOFTWARE 67 8.2. SETTING UP THE PCSD WEB UI 68 8.3..