Tag Archives: ukoug

RAC and HA SIG meting Royal Institute of British Architects September 2011

I have been looking forward to the RAC & HA SIG for quite some time. Unfortunately I wasn’t able to make the spring meeting which must have been fantastic. For those who haven’t heard about it, this was the last time the SIG met under its current name-as Dave Burnham, the chair pointed out in his welcome note.

RAC & HA SIG is going to merge with the management & infrastructure SIG to form the availability management and infrastructure SIG, potentially reducing the number of meetings to 3 for the combined SIG. This is hopefully going to increase the number of attendees and also offer a larger range of topics. I am looking forward to the new format and am hoping for a wider number of topics and greater appeal.

Partly down to the transport problems that hit London today (Victoria Line was severely delayed and apparently overground services were impacted as well) the number of attendees was lower than expected.

The following are notes I have taken during the sessions, and as I’m not the best multi-tasking person in the world there may be some grammatical errors and typos in this post for which I apologise in advance.

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RAC SIG June 2010

Good morning all!

Just wanted to put up a quick note about the upcoming UKOUG RAC SIG in June. This is going to be a really good event showing some of the most prominent members of the Oracle community:

  • Harald Van Breederode
  • Joel Goodman
  • Julian Dyke

From an infrastructure point of view Simon Haslam is going to present about the Universal Connection Pool feature for Java applications. I have done a lot of research on this subject as part of the 11th chapter of our book, “Pro Oracle Database 11g RAC on Linux” and I’m excited to hear about this from an middle-tier perspective.

You can also hear from me during the expert panel discussion after lunch.

So-please attend! You are getting the one off chance to NOT be in an Oracle office for a user group meeting, this time we are in 76 Portland Place! Chance for a great day and a good lunch!

Afterwards we traditionally gather in a pub nearby for some great networking opportunity so see you there!

RAC & HA SIG 10/02/2010

Just a quick note that I am going to present at RAC and HA SIG early February 2010 about server consolidation to RAC in my current company.

Checking the agenda I could see a lot of very good other presentations so it might be worth coming along. The only downside is that it’s in Thames Valley Park (TVP), Oracle’s corporate headquarters in the UK. Which wouldn’t be bad in itself but the food on offer there is simply terrible compared to non-Oracle venues such as Baylis House in Slough or Great George Street in London.

The agenda is now online, have a look at this link:


Hoep to see you there!

UKOUG Conference-session review part 3

The final installment of this series deals with Tom Kyte’s top 10 features in 11.2 and Wolfgang Breitling’s “seeding statistics”.

Tom Kyte – Top 10 new 11.2 features

1) dbms_parallel_execution:

I was a little late so didn’t get the essence of this. Seems to automatically do what Tom described as “poor man’s parallelism” in his effective oracle by design book. Take a huge table and instruct Oracle to subdivide it into non overlapping rowid ranges and then give it a command to work on these ranges in parallel. All of this was possible before, but required manual skripting-now it should happen without that hassle. As always, this turns an atomic update into a number of atomic operations. Need to roll back: restore or flashback database.

2) More analytics:

listagg: create a whatever separated list
nth_value: return n-th field of a partition (as in max(cola) over (partition …))

3) Execute privilege on directory

Allows us to execute code (with ext table preprocessor) in a directory
Wasn’t too clear if we we need to get the output from the preprocessor to standard out?
Leaves a number of questions, most importantly: what about security? That preprocessor executes anything within the privileges of the oracle user. What about rm -rf $ORACLE_HOME if some malicious code replaces your own script?

4) Recursive subquery factoring

As Tom said: the recusrive subquery factoring is easier to understand if you don’t know connect_by yet. Otherwise the whole syntax is confusing at first, which I have to admit, and neither does it look more elegantly. I personally like the connect_by more, even though I haven’t used it for 22 years – apparently the feature has been in the database since version 2 of the kernel. The syntax of the new recursive subquery factoring can be found in the SQL Language Reference as part of tbe select statement

With the new syntax, you get the first (root) element, called anchor member. After you’ve got it, you add the recursive members. Main use: now ANSI compatible, don’t need to change the syntax for compatibility with db2 and sybase. Don’t know why this is hyped but never mind.

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UKOUG conference 2009-session review part 2

This is the second part of my review of UKOUG conference 2009, day 1. Check out the first part as well! This picks up exactly where I left part 1 after Tom Kyte’s session.

Virtual Insanity

I remained in hall 1 to see the great presentation of James Morle. I have to say that even if you aren’t familiar with the subject of his presentations you should go to see him-he’s such a great presenter. The prank of today was a bottle of Oracle wine, distributed into 5 glasses (“everyone help yourself to your portion of Oracle”) to simulate the idea of virtualisation. James then offered insights into some of the VMWare internals alongside some competing offerings, mainly from Oracle and Cytrix (Xen) and Red Hat (KVM and RHEV). It seems the golden age of para-virtualisation is over, with AMD and Intel releasing so many features in their processors for hardware assisted virtualisation that VMWare’s offering caught up performance-wise. Personally I still love Xen (and I am writing this article on a virtual machine!) because it gives me all the performance I need on cheap hardware. I also don’t think the nehalem processors will make it into laptops, my venerable openSuSE 11.1 will support me for some more time. When it comes to performance, anything in running on vmware in userland will roughly match a physical box, but as soon as you enter kernel mode, due to modifications VMWare has to make in order for multiple instances of OSs to coexist. Again, this wasn’t tested on VT-d or IMMOU capable processors so your experience might be different. Overcommitting memory might work well with other than Oracle workloads, but James’s advise is not to use this feature in production.
All in all a very balanced presentation with the usual laugh at the beginning.

After this presentation I had some lunch and managed to see the folks from CERN which was interesting again. A great many of them were there to actually present and I briefly met Eva, their streams specialist who is responsible for pushing a lot of data from their site (tier 0) to sites all around the world (tier 1) for distributed computing. If I remember correctly this is part of the EGEE network but might be wrong there.

RAC round table

This was chaired by Julian Dyke and David Burnham (actually Julian had a problem with his voice which left him so David took over) and saw a great attendance from some reknown Oracle specialists: Piet de Visser, Phil Davies, David Burnham, Alex Gorbachev, Luca Canali, Mark Bobak, Jonathan Lewis to name just a few.

This was my first round table and I didn’t know what to expect. I greatly enjoyed the atmosphere up to the point where the discussion about block level replication started to drag on. The questions (and some answers) were:

  • Block corruption with AIX 6.1 on p595 LPARs when accessing freshly created database (in ASM). Requires a lot of tracing on the net*8 layer all the way up a strace of the oracle process, can’t be diagnosed without a system. The block corruption didn’t result of a restore from a compressed backup, the system was freshly created via dbca.
  • Update from Larry Carpenter about future of data guard/streams and golden gate. Very interesting stuff, in essence streams won’t go away and Golden Gate receives Log Miner code. Golden Gate will remain an independent product and won’t be assimilated in the streams group.
  • There are plans in Oracle to extend RMAN in order to be able to restore across endian boundaries (not to be confused with the convert command!) Before that can happen, Phil Davis was sharing details of work on a project where Golden Gate could be used to cut downtime a lot, capturing changes while the rman convert was still running on the destination platform
  • Using san block level replication:  mirroring oracle home and database to remote host still requires full license, unless you don’t mount it (or mount it only when the primary site is completely down)
  • Phil Davies: does anyone know why in clusterware active/passive setups the cluster database resource doens’t write a trace file in $CRS_HOME/log/hostname/racg ? I didn’t, neither did anyone else. That question didn’t cover 11.2, but I didn’t have time to test cold failover clusters with 11.2 yet.
  • RAC ONe node: really just a cold failover, additional benefit is mainly for maintenance. For RAC One Node you have to license only one node (apparently). Aimed primarily against VMWare

I will add yet another post about the final two sessions I attended about Tom Kyte’s top 10 11.2 features and Wolfgang Breitlings seeding statistics.

UNIX SIG 09/2009

I can’t say I like junction 15 a lot … simply too much traffic when moving off the M25.

When arriving at the venue I was still quite early and had a chance to catch up with Phil Davis and Joel Goodman from Oracle.

It seems that the credit crunch affected the numbers quite badly as the turnout was really low. I think I counted roughly 20 delegates, what a shame. Maybe I have scared them off with my presentations?

This time the user group tried something completely new, and I’m not entirely sure if it’s a good thing. The afternoon sessions were recorded and broadcast via go-to meeting. In my opinion that reduces the value of a SIG meeting quite significantly as you no longer meet the presenters in person. I always found this kind of thing useful but took little pleasure in it. The oracleracsig.org site uses a similar scheme, but the sound quality usually leaves something to be desired.

This and some technical problems aside the day started with someone from Oracle giving the audience a demo of the new and flashy user interface for metalink, now rebranded “my oracle support”. It didn’t change the quality of the support though! The highlight was the announcement that Oracle will retire the apex based classical metalink soon which is great since most desktops, especially in high security environments will never use flash. This has become even more apparent as the presenter had to download the latest version of the flash plugin. This is something you could completely forget about in most corporate environments as all hardware is locked down. Well done Oracle! The comment that they are aware of the problem and working on a solution only prompted grins.

Next was my turn, and I seriously have to apologise for the delivery of the iSCSI presentation. When I first checked the time I only had 15 minutes left and haven’t even managed to get to the first demo, the creation of an iSCSI target! Bummer. I then had to step up the already fast pace to get towards the end and rushed the whole lot. I can only recommend that you download the latest version of the presentation to have a look – all the screen prints are on it and when looking at it at a quiet moment should convey the message. Next time I’ll rehearse more and cut the demo out, or try and get a 60 minute slot. Anyway.

Phil then presented the latest support update, few surprises here.

Over to David Kurtz, long time UNIX SIG chair. He presented about graphing AWR data through Excel. Previously I read that Tanel Poder had a similar tool, called PerfSheet.xls available to do similar things. Very useful, especially since you can point it to statspack tables for pre 10g databases. Although I have done business studies at the Uni I never felt compelled to use Excel so I wasn’t that fluent with the pivoting wizard – but definitely useful things!

After lunch, I was on to present about optimising Linux kernel parameters for Oracle. I have spent so much time preparing that presentation that I could impossibly fit it all into 45 minutes. Prior to the presentation I then hid a few more slides (which are still available online!) to make it shorter, the iscsi presentation disaster still vividly in my mind. I got a few nods from Nial Litchfield, which was encouraging. Joel then pointed out that the Oracle validated RPM would do a similar job, which is of course correct. But I wanted to show what’s happening behind the scenes… I don’t think there were too many kernel hackers in the audience, but despite that the presentation can still be used as reference (and I certainly will do so).

Row migration can aggravate contention on cache buffer chains latch – a war story and the second part of David’s presentation. He is seriously smart, and used his Excel graphs to find how row chaining (or migration – there was a lot of discussion :) caused a database system to hit a brick wall after the 80th user connected. Very good troubleshooting!

Mangled or Managed – Does Grid Control deliver? Nial’s presentation was all about Grid Control and his experience with the product. All in all a very good presentation and introduction to Grid Control’s architecture. He focused on the design, the good and bad bits as well as licensing (usually a minefield). Very round, but most of the topics were already known to me from my own experience with it during the OCM preparation.

That was it then – back home via M25 and M23, after a good 1:32 I reached Brighton. I had a bit of a mixed feeling this day, most likely caused by my messy iSCSI presentation and the low number of delegates. Let’s see how RAC SIG develops, I hope to see Piet and Jason there.

Presentation Update

UNIX SIG Slough 09/2009

This is a novelty to me – going to present twice! The first presentation will deal with Linux Kernel settings and how to tune them, the second one deals with OpenFiler 2.3 and iSCSI on Linux.

RAC & HA SIG 09/2009

And if that wasn’t enough I am also going to present at the Midlands RAC SIG. The subject is the Oracle Linux Test Suite.