Northern Server Technology Day

Last Thursday’s Northern Server Technology Day organised by the UKOUG was one of the more enjoyable events I’ve attended. It helped that there were no hotels, driving or airports involved, just a simple walk to the train station, a 90 minute train journey (free wireless on hand) and a 10 minute walk at the other end. Given such a short trip, I decided to take a lazy approach and didn’t turn up until the start of the second presentation of the day – Pete Finnigan talking about Security Tools. Although I’m already familiar with a lot of the tools from Pete’s website, it was a nice summary containing a few funny security stories so it was a good start to the day.

Next was Piet de Visser sharing some of his extensive experience with 10g Upgrade Nightmares. I’ve often said that this is my favourite type of User Group presentation. I’m not mad keen on the term ‘war stories’ but users telling other users about the problems they’ve faced (along with the answers) is surely what a user group is for. Piet’s two main messages to take away were one that he’s mentioned in his previous presentations and one that was upgrade-specific

1) The more simple something is, the better.
2) Try to test against a true file copy of your database and o/s.

So that was two out of two good presentations.

After a quick break for lunch, it was time for mine. The less said about it the better, from a personal point of view. It wasn’t that it was terrible (I don’t think) and several people were very complimentary about it afterwards, but in an attempt to be informal, I tried to avoid it being too ‘scripted’. The fact is that I do have a couple of pages of notes for the presentation, so it wasn’t laziness, but chose to ignore them and take a dive around the OEM Performance Pages. It didn’t really work, most obviously because I spent the rest of the day remembering things that I would have liked to show people and didn’t. So if you didn’t know what to expect, it might have come across reasonably, but I know what it should have been like and it was nowhere near. I’m still convinced it’s a worthwhile presentation, though, and one I’ll revisit. Some of the things I forgot?

– The Trace this session button.
– Any mention of ADDM.
– Event Histograms (although that I don’t find that particular screen as useful in 10g, where it only shows the range of values since instance startup.

(Actually, this could go on for a while, so I’ll skip to the two most important …)

– The acknowledgements slide, thanking some of the guys at Oracle for their help with questions.
– Any mention of Kyle Hailey’s Simulated ASH or ASH Masters.

Fortunately, I was able to point a few interested parties to the links immediately after the presentation so hopefully ASH Masters will have a few more visitors this week.

It helped me get over my disappointment that Jonathan Lewis’ Trouble-shooting presentation was next. I thought it was one of the best 45 minute presentations I’ve seen him deliver because it dealt with an overall approach to performance analysis that utilised the various tools available and showed how they related to each other. Two of the most important sections of the presentation were near the start.

First, he broke down the Service and Wait components of R= S + W into time spent competing for resources and time spent using resources. For example, from an I/O wait perspective, some wait time is inevitable whenever you use resources (disk access time, or even cache access time) whereas some wait time could be down to queuing, unable to perform the required work. There was a bit more to it than that, but hopefully you get the general idea.

He also described the available statistics from the V$ views (or rather their low-level sources) as being in four dimensions.

Session (or Service or Systems, at higher levels)
SQL Statement
Statistic Type (e.g. Segment Statistics, Latch Statistics and so on)

By adding the fourth dimension of time, we build up a cube of data and how we analyse that cube depends on the nature of the problem we’re trying to solve.

It was a terrific presentation in my view because it often isn’t the technical details that people don’t understand when tuning performance problems, but the overall approach which will suit different types of problem. It’s one of the reasons why I wanted to do an introductory presentation on this very subject at UKOUG this year. Now I just need to find a way of saying the same things without saying the same things 😉

At the end Peter Robson, one of the directors of the UKOUG, asked Jonathan a question about complexity and Oracle’s RDBMS but I don’t think I understood the question fully and I’m not sure Jonathan understood it either or answered it correctly, so I’m trying to encourage Peter to write another guest blog entry. Fingers crossed.

Afterwards I had a few beers with several of the speakers, Lisa Dobson who had helped organise the day with the usual UKOUG support and a few old friends. (Which isn’t to say that the first two groups aren’t sub-sets of the third 😉) Apologies to Peter Lewis of the BGS for managing to spill my pint over him and his bag! I’m sure whoever was sitting near him on his train home was grateful 😉

So it was an enjoyable and interesting day out of the office and I’m glad I eventually accepted Lisa’s invitation. Thanks to everyone at the UKOUG who made it a successful day. I have to close on a negative note though (what a surprise) and the latest of a series of reminders to myself.

I must not talk to my mates during presentations
I must not talk to my mates during presentations
I must not …..