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David Paschall-Zimbel Senior Technical Consultant Oracle Database 12c Flex Clusters 27 July 2016
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Oracle Database 12c Flex Clusters Introduced in 2013 with Oracle Database 12c, Flex Clusters provide a platform to run both Oracle Databases and applications servers under control of Oracle Clusterware. 4
Topics to be discussed Flex Cluster Architecture Configuring Flex Clusters Installing and Administering Flex Clusters 5
Flex ASM Supports larger LUN sizes for Database 12c clients (32PB vs 20PB in 11gR2) Max number of disk groups supported is 511 (was 63 in 11gR2) Can rename an ASM disk in a disk group Removes node dependency between ASM instances and database instances Required when implementing Flex Clusters 6
7 Flex ASM architecture
Flex Cluster Host systems are divided into hub and leaf nodes Hub nodes resemble traditional RAC database nodes Leaf nodes are where you run applications other than a database 8
9 Flex Cluster architecture Hub and Leaf
Hub nodes Maximum of 64 in cluster Must be connected to shared storage Require access to both OCR and voting disks 10
Leaf nodes Discover Hub nodes at startup Connect to cluster via an assigned hub node Do not require direct access to shared storage Utilize the same networks as hub nodes Can not run databases Can not mount ACFS file systems directly 11
Flex Cluster Requirements Flex ASM Grid Naming Service 12
Grid Naming Service GNS used by leaf nodes to discover hub node services Requires one fixed GNS VIP for hub nodes Leaf nodes use DNS queries to the GNS 13
14 GNS Architecture
Configuration Setting node roles (hub or leaf) Minimizing the number of hub nodes in a cluster Modifying timeout for leaf communications to hub nodes Differences in node evictions between hub and leaf Adding new nodes to cluster 15
Setting node roles Query node role status crsctl get node role status node <name> Set node role status crsctl set node role [ hub leaf auto ] node <name> Status changes occur the next time clusterware is started on a particular node 16
Limiting number of hub nodes Setting a role using auto depends on the value of hubsize crsctl get cluster hubsize crsctl set cluster hubsize 16 Effective immediately, but does not change nodes with auto role until next time clusterware starts on node 17
Setting leaf communications timeout Cluster Synchronization Services (CSS) handles network connectivity issues between leaf and hub nodes leafmisscount sets the number of second to tolerate loss of communications with leaf node. Default is 30 seconds This is NOT the misscount setting, which works for hub nodes crsctl set css leafmisscount 45 18
Node evictions Node evictions for hub nodes is similar to the non-flex cluster a kernel panic is triggered Node evictions for leaf nodes causes a cluster software restart on the leaf node. Hub node eviction results in leaf nodes being evicted, after which they can reconnect to another hub node. 19
Adding cluster nodes Additional information must be provided in a flex cluster when using addnode.sh $./addnode.sh silent CLUSTER_NEW_NODES={host03,host04} CLUSTER_NEW_VIRTUAL_HOSTNAMES={host03- vip,} CLUSTER_NEW_NODES_ROLES={hub,leaf} 20
Deploying flex clusters New installation Upgrade standard cluster mode to Flex Cluster (NOT reversible) 21
22 New Installation via OUI standard or flex
23 GNS is required
24 Node roles must be chosen
25 Flex ASM network can be separated
Converting standard cluster to flex cluster NOTE: This process if NOT reversibile! 1. Enable GNS if not configured srvctl add gns -i <VIP address> -d <cluster_domain> 26
27 2. Enable Flex ASM using ASMCA
28 Convert to Flex ASM choose network
29 Execute script on node running ASMCA
Set cluster mode to flex and restart cluster 3. Set cluster mode crsctl set cluster mode flex 4. Stop clusterware on each node 5. Start clusterware on each node crsctl start crs -wait 30
Summary Flex Clusters provides a single level of control via Oracle Clusterware for both database and application servers Requirements for Flex Clusters include Flex ASM and the Grid Naming Service Hub nodes resemble traditional cluster nodes, databases will run here Leaf nodes are lightweight, do not require shared storage and should be used for applications 31
Recommended reading Clusterware Administration and Deployment Guide https://docs.oracle.com/database/121/cwadd/bigcluster.ht m#cwadd92560 32
Recommended Reading 2 Hands-on Lab using Oracle VM Templates During this lab, you are going to deploy a four-node Flex Cluster (three hubs and one leaf) with a dedicated network for Oracle Flex ASM traffic. http://www.oracle.com/technetwork/systems/hands-onlabs/deploy-rac-ovm-cluster-2101019.html 33
Recommended Reading 3 For those familiar with RAC Attack 12c implementation http://racattack.org/12c there is a set of slides outlining how to convert that two-node cluster into a Flex Cluster http://www.slideshare.net/maazanjum/racattack-labhandbook-nable-flex-cluster-and-flex-asm 34
Training The Oracle University course Oracle Database 12c: Clusterware Administration provides an introduction to Flex Clusters and also to making applications highly available with Oracle Clusterware. The labs in this course utilize flex clusters throughout, including the creation of clusterware application resources to be run on Flex Cluster leaf nodes. 35
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CONTACTS Steve Collier President Email: scollier@collier-it.com Brian Bream Chief Technology Officer / Director of Education Email: bbream@collier-it.com David Paschall-Zimbel Senior Technical Consulant Email: davidpz@collier-it.com Collier IT 2310 County Road D, West Suite 100, Saint Paul, MN 55112 Office 651-366-6446 Thank you! 37