CRS-4700: The Cluster Time Synchronization Service is in Observer mode

This is very important to keep the time of cluster nodes synchronized across the cluster. Time difference among nodes can cause issues, and sometime it can cause the node(s) restart.

There are 2 ways of keeping the time synchronized across the RAC nodes: using NTP at OS level, or using Cluster Time Synchronization Service that runs as a RAC resource.

Segment Space Growth History and Forecast

I have already written articles to get tablespace space usage history and forecast (10g and 11g, 12c and above) and database space usage history and forecast (10g and 11g, 12c and above). Here, I will explain how we can get the same information about segments, and can forecast the future growth of segments.

ORA-39510 While Starting Cluster Health Monitor Repository (MGMTDB)

MGMTDB, also called Management Repository Database was introduced in 12c Grid Infrastructure. This repository database is used to store Cluster Health Monitor data so that this monitoring data can be used for Grid Infrastructure troubleshooting. This database resource is set to start automatically on the start of Grid Infrastructure, but, there could be some scenarios where MGMTDB might not start because of some issues. One of the similar problems I face because of which MGMTDB could not start automatically. When I tried to start Management Repository Database manually, it failed to start and threw following error messages.