So Tuesday started with gales so hard that my hotel brolly got mangled on the fairly short journey from hotel to the Moscone center. In fact by the end of the day the wooden handle had snapped clean off. It’s going to be an interesting expense claim.
Apparently, my blog postings make it sound like I’m thinking OpenWorld is rubbish. Let me be clear, OpenWorld is fantastic. If you are a database professional, or even a “data processing professional” then this is the place to be. The opportunities for discussing Oracle with your peers, and straight from the people responsible for producing all this software is second to none. And that is even with the rain. It’s well worth begging, borrowing or stowing away to get to OpenWorld.
I did skip the keynotes today though. Never forget that OpenWorld is a marketing event, so you do have to pick an choose, and there is lot to choose from.
First session of the day for me:
Next Generation Grid Overview – Barb Lundhilds
I got a little bit distracted in this one, I should have realised from the title that “overview” would have been lots of generic slides. Clearly grid is getting a big marketing drive this year, and of course the phrase clusterware is out and “Grid Infrastructure” is in. ASM of course has moved from either it’s own home, or the database home into the Grid Infrastructure home.
This was the first talk I heard the word “VMware” mentioned. There was some talk about RAC One Node, but I’m saving that up for a separate blog posting.
Saw a screenshot of something called the cluster health monitor. I had never heard of this before and it does look a quite interesting tool, for diagnosing what is going on O/S wise that might be causing you a problem. A quick google turned up this page.
Top Five Essential New ASM Features of 11gR2 – Charles Kim
Again I was a little distracted, but picked up the following interesting bits.
OCR and voting disks into ASM is not compulsory in 11gR2 but, you can’t put them on raw, so it’s either ASM, NFS or a cluster filesystem. Not sure what the reasoning behind that is.
The recommended AU size is now 4MB in 11gR2.
You need rhel5 to use ACFS .
Lots of improvements in ASMCMD. I think everything can be done through this. Lots of posix type filesystem commands available, including iostat. You can run rbal from asmcmd.
Metalink Note: 948187.1 just been released has everything you need to know about acfs.
You can’t put anything into acfs that you can put into ASM itself.
Discussion of the snapshotting capability – sounds a bit like zfs on this.
I’m not too sure about acfs – you can’t even store archived redo on it. I can’t see where I’d be fitting it into my organisation, however I bumped into Julian Dyke and he was convinced that it would be of use in the real world, so it must have something.
Current Trends in Real World Performance – Andrew Holdsworth
Doug Burns has a good write up of this one.
Andrew has quite a good way of presenting, with a nice turn of phrase. He started off by saying that he “deals with the more agricultural end of database performance”
Saying that you should try and keep load below the 60-65% level and that you have to think in terms of the probability of getting onto cpu straight away. If you are at 50% load then you have a 1 in 2 chance of being scheduled straight away. This falls the more loaded the system is.
Interesting graph of throughput while increasing the number of processes running per core. The scalability really drops off. At first he was showing the best, massaged tuned numbers. He then shows more “real world” numbers and the scalability can go into reverse very quickly. The database should be cpu bound, but each sql request should ideally be scheduled straight away by the O/S. There is an optimal number of processes for each app/hardware config.
two basic problems:
inneficient sql consuming too many cpus
two many active or transient connections established to the db
Keeps saying performance problems are not difficult, it’s either crap SQL doing too much work, or you are trying to support too many connections for your hardware. keep the database working within a safe envelope of performance load.
interesting point about sql plans breaking – spend lots of effort on clustering/dr but little on designing plan stability – an unable stable can take out your system just as effectively as component failure.
When giving control back to user make sure you release all database resources, return connections to the pool. Claims connection pools should have minimum and maximum values set to the same value.
resource manager has been misunderstood. It only kicks in by default when you are at 100% cpu. You probably need it to kick in at the 65% mark. In a system with multiple instances you can use instance caging to insure no one instance grabs all the resources of a server.
All, in all a thought provoking presentation.
And to top it all I got to meet Gwen (Chen) Shapira. The explanation of the “name change” and the consequences had me rolling on the floor laughing!
And so to the blogger meetup, it was pretty good stuff, we don’t know where Alex Gorbachev has the energy to do half the stuff he does, but I certainly wish I had half the amount of energy he has!