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replica sets, Replication with mongoDB

Before we get into details of mongoDB replica sets, let's understand what is replication and why is it needed? Replication is a configuration that creates multiple copies of data by "replicating"(transferring) data from one site to one or more sites, provides redundancy and maximum availability for databases and its applications. Database is synchronized to remote sites in real time as soon as changes are loaded in to source database. These remote sites are called Disaster Recovery sites and they are strictly recommended to be spread across different geographical regions, different cities, countries, and even different continents. Nevertheless, some IT configurations do also have deployments called "Near DRs", a DR site that could be located in the same city.
Today's Disaster Recovery deployments Is DR only used in a real disaster scenario? Well, Let me share my thoughts of Disaster Recovery in today's context. A DR site in today's super fast growin…
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IPC Send timeout detected - The Story of a Database

Some errors make us panic, nervous, and beyond belief when we positively attempt to resolve a panic situation. Specific to case of Clusterware where it attempts to resolve a conflict by removing dead resources from the cluster but it suffers because of lack of additional resources to complete the task, and makes the whole situation even worst so everything that has in contact with the key resource also suffers. The key resource what we are talking is a RAC Database and the Clusterware under a panic situation is Oracle Clusterware.

Here's the environment
Oracle RDBMS 11.2.0.4.4Oracle GI 11.2.0.4.43 Node RAC Database with vault function enabledNetApp NFS Filer based Storage
What was the issue?
On Instance 3 I have noticed "IPC Send timeout". Fri Aug 14 04:46:05 2015 IPC Send timeout detected. Receiver ospid 20545 [ Fri Aug 14 04:49:55 2015 And then, Oracle has started suspending MMON actions one by one as we noticed below messages in the log Fri Aug 14 10:49:07 2015 Suspending M…

Rebuilding Standby Database Manually (11g and up)

One of my remote customers has been facing severe network outages between Production and DR sites to reasons unknown and challenges with certain geographic limitations, the bandwidth between sites is limited to 2MBPS and the replication between sites is aching slow. So, Customer has had tentative requirements to rebuild Standby more often between sites until the network issue is fully resolved.

This paper outlines the procedure to rebuild the STANDBY manually provided we have following things in place already between/on sites. And this procedure has a special case for One node RAC, Oracle dynamically applies SID naming convention in case of an online relocation. Due to this fact, I have to mention which SID to export before logging to the Database via SQLPLUS/RMAN/ASMCMD
(PR refers to - Production/Primary and PR1/PR2 are two nodes in RAC,  DR refers to - Disaster Recovery/Standby and DR1/DR2 are two nodes in RAC at DR Site)

A working Dataguard Configuration between Sites (All Paramete…

Oracle Database 12c - Far Sync Instance

A New Standby destination type is allowed in 12c Active Dataguard environment that ensures zero data loss failover and zero performance impact on Primary Database by a new concept called "Far Sync Instance". 

What is Far Sync Instance?
As we knew so far (until 11g), A SYNCHRONOUS redo transport Dataguard configuration impacts the availability and performance of Primary Database in order to protect data loss that happens due to network outages with its Standby Site. To avoid such issues and give benefit of the same zero Data loss to customers at additional cost, Oracle has introduced a new type of Instance called Far Sync Instance.  A Far Sync Instance usually is very close in distance to its Primary Database Network receives the redo synchronously from its Primary partner and then pushes it to its remote Standby Partner, plays a dummy physical standby role that actually fakes its Primary Partner to forget network outages as it takes the responsibility of managing redo to actua…