You are working on an online transaction processing (OLTP) database that runs on a machine
having multiple CPUs. The database uses normal file system storage. Examine the following
initialization parameters and their respective values for the instance:
NAME TYPE VALUE
———————————— ———- ———————-dbwr_io_slaves integer 0
db_writer_processes integer 1
filesystemio_options string NONE
disk_asynch_io boolean TRUE
The applications perform small, random I/Os in which each foreground process reads a data block
into the buffer cache for updates and the changed blocks are written in batches by the DBWR
process. You noticed free buffer waits events for your database.
To solve the problem, you increased the size of the buffer cache. But after some time, you notice
the same event again.Which three possible actions would you recommend? (Choose three.)
A.
configuring multiple DBWR processes
B.
decreasing the size of the buffer cache
C.
configuring I/O slaves for the DBWR process
D.
configuring instances to make asynchronous I/O available to DBWR
E.
spread data files over multiple disks, controllers, and I/O buses to ensure that there are no
hotspots in the I/O subsystem
Eliminating option c is bcoz where multiple dbwr is not viable there configuring I/o slaves come to use,is it?
ADE
A is right. you can configure multiple db_writer_processes to improve write
B is wrong.
C is right. with db_writer_processes=1, you can increase dbwr_io_slaves to improve write operation
D is wrong. async IO already enabled. disk_asynch_io is true
E is right. striping can help
So A.C.E. are right.
If you choose A then you can not choose C.Multiple DBWRs and DBWR IO slaves cannot coexist.If both are enabled, then the following error message is produced: ksdwra(“Cannot start multiple
dbwrs when using I/O slaves.\n”); Moreover, if both parameters are enabled,
dbwr_io_slaves will take precedence (Note ID 97291.1)
So ADE is the right choice
A is correct, as there are multiple CPUs
B is obviously wrong
C is correct, as there is only one DBWR. It is not correct, if we would have to implement A and C and the same time.
D is correct, FILESYSTEM_IO_OPTIONS should be set to ASYNCH or SETALL
E is correct.
In my opinion there are four correct solutions, but we can only choose three of them. Probably it is meant we have to implement them all at the same time, so ADE would be the best answer.
PS: We have asynchronous I/O as well as multiple CPUs, so there is no need for I/O slaves.
ADE is the correct answer.