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Oracle Traffic Director Instances, Processes and High Availability explained

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Oracle Traffic Director Instances, Processes and High Availability explained

  1. 1. Oracle Traffic Director Instances, processes and high availability explained
  2. 2. vServer 2Liberty Global | Month.Day.Year | Presenter | Event | Department | V1 OTD instances & processes • Two ‘logical’ OTD instances per OTD host vServer • Admin node is special instance that synchronizes with the OTD admin server and manages the life-cycle of configuration instances • Instance per OTD configuration deployed on the admin node • Three trafficd processes per OTD instance • Watch dog: Process spawns the primordial process. It will restart the primordial process or acceptor process if it crashes • Primordial process; main process of the instance that spawns one or more load balancer acceptor threads • Acceptor Process: the load balancer acceptor threads Admin Node Configuration Instance watchdog primordial process acceptor watchdog primordial process acceptor [oracle@otd-server1 ~]$ ps -ef | grep trafficd oracle 5665 5100 0 12:24 pts/1 00:00:00 grep trafficd oracle 19259 1 0 May05 ? 00:00:00 trafficd-wdog -d /u01/appl/oracle/otd/otdnode2/admin-server/config -r /u01/appl/oracle/products/otd -t /tmp/admin-server-f79dbba8 -u oracle oracle 19260 19259 0 May05 ? 00:00:36 trafficd -d /u01/appl/oracle/otd/otdnode2/admin-server/config -r /u01/appl/oracle/products/otd -t /tmp/admin-server-f79dbba8 -u oracle oracle 19261 19260 0 May05 ? 00:02:52 trafficd -d /u01/appl/oracle/otd/otdnode2/admin-server/config -r /u01/appl/oracle/products/otd -t /tmp/admin-server-f79dbba8 -u oracle oracle 23543 1 0 May05 ? 00:00:00 trafficd-wdog -d /u01/appl/oracle/otd/otdnode2/net-testotd-configuration/config -r /u01/appl/oracle/products/otd -t /tmp/net-testotd-configuration-f7683315 -u oracle oracle 23544 23543 0 May05 ? 00:00:36 trafficd -d /u01/appl/oracle/otd/otdnode2/net-testotd-configuration/config -r /u01/appl/oracle/products/otd -t /tmp/net-testotd-configuration-f7683315 -u oracle oracle 23545 23544 0 May05 ? 00:00:52 trafficd -d /u01/appl/oracle/otd/otdnode2/net-testotd-configuration/config -r /u01/appl/oracle/products/otd -t /tmp/net-testotd-configuration-f7683315 -u oracle
  3. 3. • VRRP protocol implemented by keepalived linux program to control active-passive VIP; VIP is only active on 1 OTD node at a time • Per OTD failover group a keep alived deamon is started • VIPs cannot be shared across OTD configuration OTD fail over group processes 3 OTDHost1 OTDHost2 Keepalived (Master) Keepalived (Backup) nic nic vip Keepalived deamon mounts the VIP VRRP heartbeats Active VIP [oracle@otd-server1 ~]$ ps -ef | grep keepalived oracle 16320 5100 0 14:39 pts/1 00:00:00 grep keepalived root 18678 1 0 Mar27 ? 00:00:41 /usr/sbin/keepalived --vrrp --use-file /u01/appl/oracle/otd/otdnode2/net-testotd-configuration/config/keepalived.conf --pid /tmp/net-testotd- configuration-f7683315/keepalived.pid --vrrp_pid /tmp/net-testotd-configuration-f7683315/vrrp.pid --log-detail root 18679 18678 0 Mar27 ? 00:08:51 /usr/sbin/keepalived --vrrp --use-file /u01/appl/oracle/otd/otdnode2/net-testotd-configuration/config/keepalived.conf --pid /tmp/net-testotd- configuration-f7683315/keepalived.pid --vrrp_pid /tmp/net-testotd-configuration-f7683315/vrrp.pid --log-detail
  4. 4. Application availability vs. Node availability Application availability with the watchdog process Provides availability of the OTD in case of a software failure with OTD ensure OTD continues to front-end request to back end applications Node availability with keepalived VRRP deamon Provide availability of OTD if the vServer crashes to ensure OTD continues to front- end request to back end applications 4Liberty Global | Month.Day.Year | Presenter | Event | Department | V1 OTD high availability Configuration Instance watchdog primordial process acceptor OTDHost1 OTDHost2 Keepalived (Master) Keepalived (Backup) nic nic vip vip 1. Keepalived on node 2 detects node failure 2. Keepalived deamon activates the VIP on the remaining host 0. Node 1 crashes Watchdog proces restarts OTD processes
  5. 5. OTD high availability • When OTD instance run as root – The life-cycle of the keepalived deamon is managed automatically under the covers by OTD when starting/stopping instances or toggling primary/backup nodes • When the OTD instance is started as non-root – the keepalived deamon has to be started and stopped separately as root (or sudo) through a script on each OTD node $ORACLE_HOME/tadm <start|stop>-failover --instance- home=/u01/OTDInstances/OTDNode1 --config=test – Check this blog for more configuration details http://exablurb.blogspot.nl/2013/06/running-otd-ha-with-minimal-root- usage.html Things you should know -1
  6. 6. OTD high availability • When the OTD instance is started as non-root – Be carefull when shutting down the primary instance from OTD console; It will NOT failover the VIP to the back up node. For this you should first stop the keepalived deamon on the node corresponding to the configuration • VIP failover roughly takes 3 seconds – The default heartbeat advertisement interval is 1 second (int_advert setting in keepalived.conf) and the failover duration is basically 3 times the advertisement interval) • An OTD process crash will not trigger VIP failover as the OTD watchdog process will restart the OTD process in-place and the keepalived deamon still runs. • Keepalived logging can be found in /var/log/messages • VIPs cannot be shared across multiple configurations Things you should know - 2

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