Help me understand what I'm seeing please

Posted by James Palmer on 30-Mar-2017 05:10

This is more a case of helping me to understand the impact of what I've done. 

OE 10.2B08, Win64. 

A customer phoned up to say that their application is slow and hanging a lot, could I take a look. I logged on and found that they weren't running an AIW, but had After Imaging and OE Replication running. So first things first I started up an AIW (and changed the startup script to include one). I changed a few other parameters that will come into force after the next restart, but this is a good starting point. 

So, what I'm seeing. All this is taken from ProTop's free web interface. 

1) AI Empty waits have gone down from 0.5-1 to practically 0. What is the impact of this on the user?

2) AIW write % has gone up to around 85% from 0 as expected. 

3) BI Busy waits have increased from <0.01 to >0.02. Is this a concern? 

4) BI Write % has dropped from ~85% to ~45%. What is the reason for this, and the impact, if any?

Read/Write activity has remained reasonably constant. 

All Replies

Posted by George Potemkin on 30-Mar-2017 06:11

> 1) AI Empty waits have gone down from 0.5-1 to practically 0. What is the impact of this on the user?

Positive impact. ;-) But I would check the latch statistics.

> 3) BI Busy waits have increased from <0.01 to >0.02. Is this a concern?

If transaction performance is increased after you eliminate the bottleneck on AI writes then the competition for BI buffers is increased as well.

> 4) BI Write % has dropped from ~85% to ~45%. What is the reason for this, and the impact, if any?

It's normal. AIW writes to BI file before AI file when it's needed.

Posted by James Palmer on 30-Mar-2017 06:32

Thanks George. Appreciate your time.

This thread is closed