Have you ever heard that the speed of the system is determined by its slowest component ? I am made painfully aware of that every time I do data migrations.
I.e. it doesn’t matter if you have 64 core systems with 100+ Gb of memory on either end if the majority of time is spent waiting for data to trickle across a slow 1 Gb network link.
Watching data trickle for hours, while the rest of the system is doing nothing is a pretty frustrating experience. But limitations breed creativity … so lately, I’ve been experimenting with several different copy techniques to see if there is any way transfer speed can be improved, perhaps using some of the idle capacity to speed things up.
Sometimes when you trace things, you can discover some really interesting (and unexpected) stuff.
For example, here is a simple way to “freeze” your ORACLE database, which I “discovered” while tracing system calls in LGWR process (ORACLE 126.96.36.199 on Linux 2.6.18 ×64).
A very brief update.
One of the smaller (and nicer) part of ORA_MEM package is ora_cpu.pl utility that shows graphically what active db processes are doing at the moment … be it running SQL, accessing db object or waiting for something.
As an added benefit, it also shows some important OS statistics, such as process state or ‘spot’ CPU utilization for your database sessions.