System Statistics Gathered in Exadata Mode – When Are They Relevant?

The aim of this post isn’t to explain what the “exadata mode” is. Hence, if you don’t know what it is, before continuing reading have a look to this post published on Kerry Osborne’s blog. The only think I would like to add is that the “exadata mode” is available (more...)

My #OOW13 Session: Are Indexes Unnecessary in Exadata

Thanks to all those who came to my session "Are Indexes Unnecessary in Exadata" at Oracle Open World 2013. Considering it was late afternoon of the last day of the conference, especially after the appreciation concert, it was a pleasure to see a packed room. Judging by the interaction I (more...)

Stuck Timezone Upgrades and Smart Scans

I heard a strange report from a client late last week - they weren't getting any smart scans on their Exadata - a data warehouse, no less (and we checked to see if cell_offload_processing was set to true).  Queries would run normally, but for some reason, the "cell physical IO (more...)

Love your Exadata! Use Exadata Database DBRM

You have bought Exadata after spending a fortune and more importantly after convincing everybody in the organization and in your family that this is the ultimate resource machine which hosts the world’s best database, Oracle 12c. You are not off the mark with those statements, though one might term them bit exaggerated. The point is […]

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Virtualization on Exadata?

A while back, I noticed this session in the Open World 2013 content catalog.  I didn't think much of it at the time, other than that it had a catchy title.  The other day, I downloaded the latest Exadata deployment utility via the OneCommand tool.  I noticed something a little (more...)

Analyzing page allocation failures on Exadata

I have seen several clients who are struggling to decode page allocation failures on Exadata, in this post i will try to explain how to read the backtrace. The following is an anonymized client case where page allocation failures are leading up to a node reboot.

Jan 1 11:58:02 dm01db01  (more...)

Reminder – “Getting Ready for Exadata” Seminar in London

Just a quick reminder - I'll be presenting my "Getting Ready for Exadata" seminar in London on July 1. We'll cover various topics on what you need to know before you purchase an Exadata and how to manage one of these systems on a daily basis. We'll have lots of (more...)

Patching an Exadata Compute Node

An Oracle Exadata Full Rack consists of 8 DB compute nodes. Oracle has shifted the strategy to patching the exadata in 11.2.3.2.0 onwards to using Yum as the method of patching. the Quarterly Full Stack  does not include the DB Compute nodes patches anymore. So that (more...)

dbnodeupdate.sh on Exadata Compute Nodes

Rene Kundersma at Oracle just published a nifty new utility named dbnodeupdate.sh that will assist with the sometimes-cumbersome process of updating the compute nodes in an Exadata environment.  Starting last year with 11.2.3.1.0, Oracle introduced yum updates for the Exadata compute nodes.  Previously, each Exadata (more...)

Speaking at E4 2013! … and some Exadata Patents good stuff

I’ll be co-speaking with Tyler Muth at E4  and we will be talking about Performance Visualization… some of you may already know that I’m really a big fan of Tableau and just to give you an example on what the tool can do I’ve consolidated all the different viz that (more...)

gv$cell_thread_history ; A Nice View

There are certain dictionary views available to monitor the Exadata cells from the database.One of the view is gv$cell_thread_history. This view is very interesting as it delves down to the session level with its serial number, SQL, specific cell, instance and also which Exadata object was waited and every (more...)

Exadata Hybrid Columnar Compression

The basic idea behind the Exadata Hybrid Columnar Compression (hereby referred as EHCC) is to reprise the benefits of column based storage while sustaining to the fundamental row based storage principle of Oracle database. Oftentimes  the databases following column based storage claim that comparatively they needs less IO to retrieve (more...)

ASM AU Size And LMT AUTOALLOCATE

When using Locally Managed Tablespaces (LMT) with variable, system managed extent sizes (AUTOALLOCATE) and data files residing in ASM the Allocation Unit (AU) size can make a significant difference to the algorithm that searches for free extents.The corresponding free extent search algorithm when searching for free extents >= the AU size seems to only search for free extents on AU boundaries in order to avoid I/O splitting.Furthermore the algorithm seems to (more...)

Exadata Article as NYOUG’s Article of the Year 2012

Exadata Article as NYOUG's Article of the Year 2012The Editors of New York Oracle User Group (NYOUG) publication - TechJournal - chose my article Exadata Demystified as the Article of the Year. Here is the snippet from the Editorial:

And the Award Goes To …


The Editor’s Choice Award (more...)

Exadata versus IPv6

Recently one of my customers got a complaint from their DNS administrators, our Exadata’s are doing 40.000 DNS requests per minute. We like our DNS admins so we had a look into these request and what was causing them. I started with just firing up a tcpdump on one of the bonded client interfaces on a random compute node:

[root@dm01db01 ~]# tcpdump -i bondeth0 -s 0 port 53
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on bondeth0, link-type EN10MB (Ethernet), capture size 65535 bytes
15:41:04.937009 IP dm0101.domain.local.59868 > dnsserver01. (more...)

Exadata Smart Scan Projection Limitation

Here is an interesting limitation to Exadata Smart Scans - if more than 254 columns from a table (not HCC compressed, more on that in moment) need to be projected, Smart Scans for that particular segment will be disabled and Exadata will fall back to conventional I/O. This means that the number of columns in the projection clause can make a significant difference to performance, since only Smart Scans allow taking advantage of offloading and (more...)

Online patching: The Good, the Bad, and the Ugly

I’ve worked on 24×7 systems for more than a decade, and I have a real dislike of downtime. For one, it can be a real pain to agree any downtime with the business, and while RAC can and does help when you do work in a rolling fashion, there is still risk.

The promise of online patching has been a long one, and it is only recently that I dipped my toe in the water with them. Unfortunately, they are not a panacea, and in this blog posting I’m going to share some of the downsides.

Of course not all (more...)

Slides and Offline Recording of my NYOUG Webinar

I have announced my webinar on Oracle ZFS Storage Appliance for Exadata Backup & Recovery in NYOUG DBA webinar series. You can download webinar slides and voice recod from NYOUG web site


NYOUG SIG Webinar: Oracle ZFS Storage Appliance for Exadata Backup & Recovery

In Friday December 14, 2012 at 12:00 PM -1:00 PM EDT I will be giving a webinar for NYOUG SIG with the following abstract
When it comes to the backup and recovery infrastructure of the Exadata Database Machine, conventional solutions often have only limited performance to keep up with Exadata throughput, whereas Oracle ZFS Storage Appliance can be configured as a very fast, capable, and easy-to-manage backup and recovery solution for any Exadata environment. In this session Husnu Sensoy will describe some of the configuration possibilities of the ZFS Storage Appliance to create a flexible backup and recovery environment for Exadata, (more...)

Scripted Collection of OS Watcher Files on Exadata

Uncategorized
| Nov 2, 2012
I’ve been working a lot with graphing DB and OS metrics in R. I find it especially useful in Exadata POVs (proof of value) to gather and graph the oswatcher vmstat files for the compute nodes and iostat for the cells. For an example, take a look at this graph (PDF, 168 KB) of what [...]