Oracle System Architecture Interview Questions

Name the Oracle background process ?

Dbwr - database writer.Lgwr - log writerckpt - check pointsmon - system monitorpmon - process monitorarch - archiverreco - recoverdnnn - dispatcher, andlckn - locksnnn - server.

What are the different Oracle kernel layers

What is user process ?

A user process is created and maintained to execute the software code of an application  program.  it  is  a  shADOw  process  created automatically to facilitate communication between the user and the server process.

What is server process ?

Server  process  handle  requests  from  connected  user  process. A server process is in charge of communicating with the user process and interacting with Oracle carry out requests of the associated user process.

What are the two types of server configurations?

Dedicated server configuration and multi-threaded server configuration.

What is dedicated server configuration?

In a dedicated server configuration a server process handles requests for a single user process.

What is a multi-threaded server configuration ?

In  a multi-threaded server configuration many user processes share a group of server process.

What is a parallel server option in Oracle ?

A configuration for loosely coupled systems where multiple instance share a single physical database is called parallel server.

What does dbwr do ?

Database  writer  writes  modified blocks from the database buffer cache to the data files.

What are functions of pmon ?

Process monitor (pmon)  performs process recovery when a user process fails pmon  is  responsible  for cleaning up the cache and freeing resources that the  process  was using pmon also checks on dispatcher and server processes and restarts them if they have failed.

What is the function of arch ?

Archiver  (arch) copies the on-line redo log files to archival storage when they  are  full.  arch is active only when a database's redo log is used in archivelog mode.

What is function of reco ?

Recover (reco) is used to resolve distributed transactions that are pending due  to  a  network  or  system failure in a distributed database. At timed intervals,the  local  reco  attempts  to  connect  to  remote databases and automatically ...

What is the function of dispatcher (dnnn) ?

Dispatcher   (dnnn)  process  is  responsible  for  routing  requests  from connected user processes to available shared server processes and returning the responses back to the appropriate user processes.

How many dispatcher processes are created ?

Atleast one dispatcher process is created for every communication protocol in use.

What is the function of lock (lckn) process ?

Lock  (lckn)  are  used for inter-instance locking when the Oracle parallel server option is used.

What is the maximum number of lock processes used ?

Though  a single lck process is sufficient for most parallel server systemsupto ten locks (lck0,....Lck9) are used for inter-instance locking.