Oracle and SnapMirror active sync - total loss of connectivity
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The result of a storage system or site failure is nearly identical to the result of losing the replication link. The surviving site should experience a roughly 15 second IO pause on writes. Once that 15 second period elapses, IO will resume on that site as usual.
If only the storage system was affected, the Oracle RAC node on the failed site will lose storage services and enter the same 200 second disktimeout countdown before eviction and subsequent reboot.
2024-09-11 13:44:38.613 [ONMD(3629)]CRS-1615: No I/O has completed after 50% of the maximum interval. If this persists, voting file /dev/mapper/grid2 will be considered not functional in 99750 milliseconds. 2024-09-11 13:44:51.202 [ORAAGENT(5437)]CRS-5011: Check of resource "NTAP" failed: details at "(:CLSN00007:)" in "/gridbase/diag/crs/jfs13/crs/trace/crsd_oraagent_oracle.trc" 2024-09-11 13:44:51.798 [ORAAGENT(75914)]CRS-8500: Oracle Clusterware ORAAGENT process is starting with operating system process ID 75914 2024-09-11 13:45:28.626 [ONMD(3629)]CRS-1614: No I/O has completed after 75% of the maximum interval. If this persists, voting file /dev/mapper/grid2 will be considered not functional in 49730 milliseconds. 2024-09-11 13:45:33.339 [ORAAGENT(76328)]CRS-8500: Oracle Clusterware ORAAGENT process is starting with operating system process ID 76328 2024-09-11 13:45:58.629 [ONMD(3629)]CRS-1613: No I/O has completed after 90% of the maximum interval. If this persists, voting file /dev/mapper/grid2 will be considered not functional in 19730 milliseconds. 2024-09-11 13:46:18.630 [ONMD(3629)]CRS-1604: CSSD voting file is offline: /dev/mapper/grid2; details at (:CSSNM00058:) in /gridbase/diag/crs/jfs13/crs/trace/onmd.trc. 2024-09-11 13:46:18.631 [ONMD(3629)]CRS-1606: The number of voting files available, 0, is less than the minimum number of voting files required, 1, resulting in CSSD termination to ensure data integrity; details at (:CSSNM00018:) in /gridbase/diag/crs/jfs13/crs/trace/onmd.trc 2024-09-11 13:46:18.638 [ONMD(3629)]CRS-1699: The CSS daemon is terminating due to a fatal error from thread: clssnmvDiskPingMonitorThread; Details at (:CSSSC00012:) in /gridbase/diag/crs/jfs13/crs/trace/onmd.trc 2024-09-11 13:46:18.651 [OCSSD(3631)]CRS-1652: Starting clean up of CRSD resources.
The SAN path state on the RAC node that has lost storage services looks like this:
oradata7 (3600a0980383041334a3f55676c697347) dm-20 NETAPP,LUN C-Mode size=128G features='3 queue_if_no_path pg_init_retries 50' hwhandler='1 alua' wp=rw |-+- policy='service-time 0' prio=0 status=enabled | `- 34:0:0:18 sdam 66:96 failed faulty running `-+- policy='service-time 0' prio=0 status=enabled `- 33:0:0:18 sdaj 66:48 failed faulty running
The linux host detected the loss of the paths much quicker than 200 seconds, but from a database perspective the client connections to the host on the failed site will still be frozen for 200 seconds under the default Oracle RAC settings. Full database operations will only resume after the eviction is completed.
Meanwhile, the Oracle RAC node on the opposite site will record the loss of the other RAC node. It otherwise continues to operate as usual.
2024-09-11 13:46:34.152 [ONMD(3547)]CRS-1612: Network communication with node jfs13 (2) has been missing for 50% of the timeout interval. If this persists, removal of this node from cluster will occur in 14.020 seconds 2024-09-11 13:46:41.154 [ONMD(3547)]CRS-1611: Network communication with node jfs13 (2) has been missing for 75% of the timeout interval. If this persists, removal of this node from cluster will occur in 7.010 seconds 2024-09-11 13:46:46.155 [ONMD(3547)]CRS-1610: Network communication with node jfs13 (2) has been missing for 90% of the timeout interval. If this persists, removal of this node from cluster will occur in 2.010 seconds 2024-09-11 13:46:46.470 [OHASD(1705)]CRS-8011: reboot advisory message from host: jfs13, component: cssmonit, with time stamp: L-2024-09-11-13:46:46.404 2024-09-11 13:46:46.471 [OHASD(1705)]CRS-8013: reboot advisory message text: At this point node has lost voting file majority access and oracssdmonitor is rebooting the node due to unknown reason as it did not receive local hearbeats for 28180 ms amount of time 2024-09-11 13:46:48.173 [ONMD(3547)]CRS-1632: Node jfs13 is being removed from the cluster in cluster incarnation 621516934