Public Appearances

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Availability Infrastructure & Management SIG March 14th 2012

I am proud to be able to speak at the first instalment of the Availability, infrastructure and management SIG on March 14th in  the London City office.

The event is announced on the UKOUG website here:

Unfortunately I will be between you and lunch! I hope that works out, and I don’t overrun.

martin.bach's picture presentation October 27 2011

For all of those who aren’t tired of listening to me yet there is good news: I am presenting a webinar at on October 27th 2011. I will most likely be around 17:00 UK time as the meetings start 09:00 PST. I agreed with the committee that we have performed a lot of nitty-gritty down to the very low level, and should probably do a more high level overview presentation as well. As it happens, I am starting my seminars with exactly that!

For your convenience the abstract and summary are shown below-hoping to see you online.

An Introduction to Oracle High Availability

This introductory level session aims at providing an overview of Oracle High Availability options to users of traditional single instance Oracle deployments who are interested in ways to make their database more highly available.

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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.

Support Update-Phil Davies

The first presentation was Phil Davies’s support update which provided the usual good overview of what is currently relevant in Oracle support. My personal highlight was the fact that you can limit the number of child cursors per statement via an underscore parameter. This worked will for his customer who had to use CURSOR_SHARING set to FORCE.

Also there is an interesting problem related with Data Guard, the RFS process and overwriting of arbitrary files on the standby.

Plugging in the Database Machine-Joel Goodman

Joel delivered a very good presentation about monitoring the Exadata Database Machine. What’s great about Joel is his depth of knowledge and his ability to enrich the presentation with annotations both from the classroom as well as real life. If you haven’t bookmarked his blog yet, it’s well worth doing so from .

I personally have seen this presentation internally at a customer site, but still learned new things. Especially about the SNMP traps being routed back into the MS process on the cells, which can then be checked via cellcli.

Every so often the current metrics are flushed to disk, and move from metriccurrent to metrichistory. The metric history is kept for 7 days by default, and I think I’ll look at extending my monitoring solution to heave them into the database into a statspack-like schema.

Another interesting fact to know is that ADR is also available on the cells, including the adrci command with all its options.

Plugins for OEM 11.1 include

  • Infiniband plug-in
  • Cisco plug-in
  • ILOM (only for database nodes)
  • Exadata plug-in
  • PDU plug-in
  • KVM plug-in

Of course for these to work you have to install the agents on the database servers (only!). Once the agent is deployed, the plug-ins need to be deployed to the Grid Control infrastructure first before they are passed on to the agents.

The Exadata plug in requires the database server’s agent software owner to use passwordless authentication to the cell’s cellmonitor accounts. Also, the cells must be configured to report SNMP traps to Grid Control. I guess a thorough read of the plugin installation documentation might be needed.

I personally regarded the other plugins to be of less importance and decided not to record them here-I’m sure there is a white paper on Oracle’s website somewhere.

An interesting side note on the KVM which is missing in the x2-8 is the fact that you could still access the KVM if the internal Cisco switch failed. This is simply because the KVM does NOT go through the Cisco Ethernet switch, but rather directly connects to the corporate network.

High availability for agent monitoring a target is described in MOS note 1110675.1-a sure candidate for further investigation.

After Joel’s presentation we had a great discussion with Sally and Jason about disk failures in Exadata and the quarantine. In certain situations, if multiple disks fail only high redundancy can prevent complete disaster.

Also one should really be careful to not have negative numbers in V$ASM_DISKGROUP.USABLE_FILE_MB. If you do, it’s not an immediate problem, but an imminent danger as soon as a failgroup goes offline-there simply isn’t enough space for an ASM rebalance operation. Summary: you should not run your ASM mirrored disk group at full capacity to avoid trouble. Oh yes, and you should have at least 3 failgroups in a normal redundancy diskgroup.

I suggest you read Joel’s blog entry “mirror mirror on the Exadata” for a more thorough discussion of ASM mirroring in Exadata.

Exadata Storage and Administration-Corrado Mascioli

Corrado is a colleague of mine working in engineering on the same site. He has got great experience in patching Exadata and automating the process.

The cells are shipped with the software pre-installed, based on Oracle Linux. The most important accounts available are

  • root
  • celladmin
  • cellmonitor

These have various degrees of power, listed here in descending order.

Cellcli is the main interface to the storage cell allowing the user to perform administrative tasks.

The main cell processes are:

  • CELLSRV: mainly uses iDB to communicate with the RDBMS nodes and satisfies the I/O requests.
  • Management Server – MS
  • Restart Server – RS

Flash storage is something I blogged about earlier, see here:

Flash disks can be used either as Exadata Smart Flash Cache or Grid Disks, i.e. “ASM disks”. I haven’t created flash grid disks yet but suppose you would want to group the grid disks on a cell group to create failure groups.

David Burnham raised an interesting question about differentiating the flash cache in Exadata from the one available to the mere mortals, available with a patch or 11.2.0.x on Linux and Solaris.

The PCI cards you put into a database server are like another level of buffer cache, whereas the Exadata Smart Flash Cache is a) unique to Exadata and b)

Next Corrado explained the link between the physical disk, LUN, cell disk and grid disks. Especially the 30G taken away from the first 2 cell disks cause an interesting dilemma when it comes to the allocation of space for the DBFS disk group (former SYSTEMDG). For each cell, cell disks 3-12 reserve the last 30G on the innermost tracks of the disk for DBFS_DG.

The DATA diskgroup will by default use the fastest, outermost tracks of the disks, +RECO will take the middle of the disk whereas DBFSDG uses the innermost like I just said.

DBFSDG is mostly used for the database file system but also for the OCR and the voting files. DBFS looks like a normal file system for the end user.

I wonder if you could create a grid disk on a specific number of cell disks? I’d have to check the create griddisk command in cellcli …

All the settings are easily accessible with the cellcli commands list {lun,physicaldisk,celldisk,griddisk}.

The grid disks are visible to ASM using the CELL library (V$ASM_DISK.LIBRARY), and use the path 0//. By the nature of the technology all 14 x 12 disks are visible in V$ASM_DISK.

Each cell is its own failure group-which makes sense, given the fact that all disks share a single point of failure. Also worth remembering that since there is no storage array mirroring hence we resort to ASM redundancy.

Corrado shared lots of practical advice about creating grid disks and reconfiguring a storage cell using cellcli.

Panel Session-all speakers and The private cloud-Martin Bach

Well that’s me in the middle of the action-I hope someone else covers these.

Managing ASM redundancy-Julian Dyke

Julian started the RAC SIG in summer 2004, and surely had to have the honour to have the last slot on the current designation.

His opening theme has been a comparison of single threaded CPU performance for different architectures including Intel, AMD, SPARC, and IBM Power. Contact him personally if you are interested in the real results, it suffices to say that the 5600 Xeons are the fastest. I wonder if anyone has a recent Itanium processor willing to run the benchmark.

Interesting twist about a two node cluster and ASM tablespace creation with different allocation units-setting the AU size to 32M reduced the tablespace creation time for a 20G tablespace to a few seconds. There seems to be a lot of inter-ASM instance message exchange.

Following this Julian continued with the discussion of the ASM utility kfed to dump disk group metadata followed by a graphic visualisation about extent allocation and maintenance during ASM rebalance operations.

The nugget for today was to learn why the ACD uses 42 entries and ASM_POWERLIMIT used to be 11. 42 is self-explanatory. The power limit of 11 is a true classic-it’s one faster (louder), in honour to Spinal Tap.

There are a number of new features in 11.2 Julian mentioned which I covered in Chapter 8 of “Pro Oracle Database 11g RAC on Linux”. Of particular interest was the location of the 3rd voting file in stretched and non-stretched RAC if you used two different SANs for the first 2 failgroups. Oracle now supports the iSCSI/NFS approach for the third voting disks previously recommended for stretched RAC in “normal” RAC as well.

One of the features Julian didn’t mention was the location of the snapshot controlfile which since also has to reside on shared storage-there is a note on MOS for this.

Oh yes, and then there was the demo about ASM normal redundancy which continued the discussion started at the last RAC SIG.


I enjoyed today a lot, met lots of interesting people and had many technical discussions about all sorts of things. One thing I’m looking forward to is the change of the SIG format, especially hoping for more attendees to make it even more attractive.

Unfortunately, due to the change of date for the Management and Infrastructure SIG which I will now miss I couldn’t see Piet de Visser whom I haven’t seen since Birmingham last year. Maybe I need to get to work on the same site as he does for a few weeks to catch up properly.

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Oracle RAC SIG presentation tips

Yesterday I proudly presented a one hour training class about upgrading to Oracle 11.2 RAC at This was the first time I presented using this facility and thought it might be useful for others to learn about the procedures and hopefully encourage other speakers to follow suit. It’s really straight forward and there is nothing to worry about! Especially if you are already familiar with webex, presenting should be a piece of cake. But I’m getting ahead of myself.

So how do you get to present?

The Proposal

First of all, speak to the RAC SIG board, you should be able to get the email addresses from the website. You need to submit an abstract of your talk to the committee, and once they have decided to go ahead it’s all about scheduling. You should know that Oracle RAC SIG records your session, whilst Oracle University kindly provide the infrastructure in form of their Webex facility and conference calls.

The Technical Part

For those of you who don’t know webex, it’s a Cisco product which you can use to host web conferences on. It is very good for all sorts of screen sharing to a larger audience, and as a RAC SIG presenter you are effectively sharing your desktop with the participants. But image only doesn’t cut it, we need audio as well! Audio can either be part of the presentation stream via the webex-presentation, or you need to dial in to a toll-free number (available from I have tested this both as a presenter and a participant, and it works really well. Just be sure to dial in 5-10 minutes early, as you will have to be connected to the correct meeting via an operator. This is especially true for the presenter.

Leading up to the Event

I suggest you contact Oracle RAC SIG 1-2 weeks prior to the event if your presentation has not yet appeared on the website. After all we would like some participants to listen to our talk! Remember that the website and everything is mainly run by volunteers so be patient and don’t expect a reply in 5 minutes.

When the time of the event approaches, roughly 3-5 days before it starts, you will get an email from the team informing you about the URL for the webex presentation, the dial-in code and some reminders for a successful session, which I’d like to repeat here:

  • Use a landline – not cell phone. Voice quality suffers too much on a mobile device
  • Don’t use a headset unless it is really, really good!  Use the handset. It might even be that the use of a cordless phone has a negative impact on the sound quality
  • Get on the webcast 15-20 minute s early to test connectivity and sound quality

Also ensure you send Oracle your slides to go to the website a few days before the scheduled event. At the time of writing, Dennis Karashima from Oracle was our liaison (again check the website for up to date information).

On the Day

If you are in the lucky situation that your employer actively endorses your presentation and it’s part of your work anyway, then it may be a good idea to use an office Internet connection and office phone (granted explicit permission from the company).

Otherwise, if you are not in the US, having a fast and reliable Internet connection upstream can really reduce latency. A good phone helps as well, and again, don’t use a cell phone, use a land line instead.

Roughly 30 minutes before the start of the webcast, join the webex as a participant, even if you are the presenter. The whole procedure is initiated from Oracle. Also ensure to dial in to your toll free number for the conference call. You are greeted by an operator, give him/her your passcode and they will put you through to the line where Oracle are already waiting. You are greeted by the very kind Dennis Karashima who is guiding you through the initial steps.  These include a connectivity test for the recording as well as some feedback about audio quality. In my case, I was advised to pause for 2-3 seconds after slide transitions or animations to allow the other participants to follow. Again, a better Internet connection can reduce the latency here.

Only at that stage are you told to share your desktop-don’t try this before you are prompted :) After the setup is complete, you will hear the advertisement from Oracle University, after which it’s your show to run.

Good luck!

If you are in a situation to open a Q & A session, announce this at the end of your presentation and liase with the operator to get questions.

That’s it-not scary at all, and really something more of us should do.

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Additional date for my Grid Infrastructure seminar in the UK

I was very pleasently surprised that Oracle University are offering another day for my “Grid Infrastructure and Database High Availability Deep Dive” seminar. In addition to the immenent seminars in June (I blogged about them earlier), this one is in London, England. For anyone interested, here is the link:

The date has been set to October 10th, so there is plenty of time still, but nevertheless I hope to see you there!

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Summer Seminars

I am doing a couple of one day seminars with Oracle University, currently planned for Austria and Switzerland. They go by the title “Grid Intrastructure and Database High Availability Deep Dive”, and can be accessed via these links.

To save you from having to get the abstract, I copied it from the Oracle University website:

Providing a highly available database architecture fit for today’s fast changing requirements can be a complex task. Many technologies are available to provide resilience, each with its own advantages and possible disadvantages. This seminar begins with an overview of available HA technologies (hard and soft partitioning of servers, cold failover clusters, RAC and RAC One Node) and complementary tools and techniques to provide recovery from site failure (Data Guard or storage replication).

In the second part of the seminar, we look at Grid Infrastructure in great detail. Oracle Grid Infrastructure is the latest incarnation of the Clusterware HA framework which successfully powers every single 10g and 11g RAC installation. Despite its widespread implementation, many of its features are still not well understood by its users. We focus on Grid Infrastructure, what it is, what it does and how it can be put to best use, including the creation of an active/passive cold failover cluster for web and database resources. Special focus will be placed on the various storage options (Cluster File System, ASM, etc), the cluster interconnect and other implementation choices and on troubleshooting Grid Infrastructure. In the final part of the seminar, we explore Real Application Clusters and its various uses, from HA to scalability to consolidation. We discuss patching and workload management, coding for RAC and other techniques that will allow users to maximise the full potential of the package.

See you there if you are interested!

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Presenting at Miracle Open World 2011

Just a really quick post about my appearance at Miracle Open World 2011 in Denmark next month:

I strongly recommend you to have a look at the agenda and speakers, there are lots of fellow Oak Table members sharing their knowledge-quite an incredible lineup and a great honour for me to be there.

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Logica Guru4Pro – Amstelveen

Yesterday I returned from a trip to Amsterdam where I presented about Grid Infrastructure 11.2 as part of Logica’s Guru 4 Pro series. I have to say it has been a very pleasant experience! And it marked the first time I presented outside the UK as well.

Logica Holland runs a series of events where renowned experts present about the latest and greatest developments in their field. I was very pleased getting an invitation to the series, and gladly accepted. I opted to give the audience a “close look at Grid Infrastructure”. I think Oracle University would have termed it a “Deep Dive”, and a deep dive it was!

The flight from London Gatwick, my “home” airport to Amsterdam is very short indeed, I had the feeling I spent more time on taxiways than in the air. Upon arrival I was picked up by Dennis van Onselen, Logica’s Practice Manager. I really appreciate not having had to resort to a taxi to the venue!

Before the main event kicked off at 18:30 in the evening there was time for a session with Logica employees. For about two and a half we went through pros and cons of various technologies in the Oracle portfolio, and had a really good discussion along the way. I hope the attendees found it useful.

After a short break, I started my talk which was well received by the audience. I recognised some familiar faces in the audience, and was very pleased to also see Piet de Visser who I haven’t met all year and who introduced me to Anjo Kolk-I didn’t know he was part of the audience as well. After the presentation which was the longest I gave so far (around 90 minutes) we had a great discussion about the contents and high availability strategies in general. I felt a little strain on my voice, even though I was mike’d up after a cold I was suffering from at the weekend. I can fully understand singers now who can’t make it to their concert. But I’m back to normal now, hoping it won’t repeat itself during next week’s UKOUG conference.

One of the really good things that came out of this session was the prospect of returning to Holland for more presentations about RAC and all things around it. I would be delighted to return, anyone interested please drop me a line. And that of course includes Miracle!

By the way, I have converted the presentation to a PDF, and it can be downloaded here.

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UKOUG RAC&HA SIG September 2010

Just a quick one to announce that I’ll present at said event. Here’s the short synopsis of my talk:

Upgrading to Oracle Real Application Cluster 11.2

With the end of premier support in sight mid 2011 many business start looking at possible upgrade paths. With the majority of RAC systems deployed on Oracle 10g, there is a strong demand to upgrade these systems to 11.2. The presentation focuses on different upgrade paths, including Grid Infrastructure and the RDBMS. Alternative approaches to upgrading the software will be discussed as well. Experience from migrations performed at a large financial institution round the presentation up.

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