Pythian Group

I just got an Exadata Customer Advisory e-mail from Oracle, identifying “an important issue that needs your immediate attention” and pointing to MOS note 1265396.1.

Note 1265396.1 talks of an issue with disk controllers in Exadata storage servers declaring false disk failures. In some “rare cases”, multiple such false failures occur at the same some, potentially causing data loss.

The issue applies to Sun (V2) database machines only, not the HP V1 or database machines or with the newer X2-2/X2-8 database servers.

The only fix is to upgrade to the newly-released version 11.2.2.1.1 of the storage server software. A combination of an upgrade and manually forcing disks back online at the disk controller and ASM levels can “bring back” the data in case of loss, assuming the disks haven’t been physically removed of course.

The 11.2.2.1.1 patch will run on any 11.2.0.1+ databases, though either 11.2.0.2 or 11.2.0.1 plus bundle patch 6 is recommended. If the database patches are in place, the storage server patch can be applied in a rolling fashion without downtime.

I’ll be giving a webinar about Exadata implementation, where I’ll be talking about Exadata features and how best to use them. I’ll also be sharing some lessons learned from my own implementation experience.

The webinar will be on Wednesday August 11 at high noon eastern time. Note that this is a change from the previous date.

To register, visit https://www2.gotomeeting.com/register/171889707. For more Pythian webinars, visit http://www.pythian.com/library/webinars/.

This is my first mobile post so please excuse any typos. I must admit though that T-Mobile 3G is _fast_.

Although many electrons have been expended discussing Exadata’s features, storage indexes tend to figure last, with a vague mention of row elimination in heavily clustered data. Even Oracle’s Exadata software user guide devotes barely half a page to them. Unlike the better known smart scanning features though, storage indexes have an important advantage: rather than offloading workload to storage cells, they eliminate the need to do the I/O at all.

Here are some sample statistics taken from an actual production system:

SQL> select name,value from v$sysstat where name in ('physical read total bytes','cell physical IO bytes saved by storage index');

NAME                                                                       VALUE
---------------------------------------------------------------- ---------------
physical read total bytes                                        468779565615616
cell physical IO bytes saved by storage index                    251319174832128

That’s right, over a third of all I/O was avoided entirely because of storage indexes. Interested now?
Read the rest of this entry . . .

Pythian has full-featured Oracle Exadata Services complete with successful implementations and reference customers.

When Oracle first introduced Exadata at OpenWorld 2008, it was aimed squarely at the data warehouse market dominated by Teradata, Netezza, and other pure-play vendors. Version 2, introduced a year later, has expanded the scope to include general-purpose mixed and even pure transaction processing workloads. Marketing claims abound with reports of 10x and faster speed improvements.

In this series of articles (part 2 here and part 3 here), we’ll explore the major components of Exadata and the Oracle Database Machine and take a peek at how they’re designed with performance and scalability in mind.

Going against the industry trend of embedding database-specific logic in hardware, Exadata makes use of commodity off-the-shelf hardware components, with an underlying open source operating system stack. While arguably such a common hardware architecture makes it easier for competitors to copy functionality, it also gives Exadata a well-understood, stable, and tested platform that’s constantly evolving higher speeds and capacities.

Database nodes

The database nodes in an Oracle Database Machine will be familiar to anyone who has worked with Oracle RAC in a Linux/x86 platform. They consist of exactly the same Sun Fire x4170 1U servers sold for general-purpose computing, but come maxed out in terms of configuration: Read the rest of this entry . . .

A few months ago, we had a test instance complaining that it couldn’t write to ASM. This was an 11.1.0.7 single (non-RAC) instance on Oracle Enterprise Linux 5, using ASM for the storage. We first saw these errors in the alert log:

ORA-15032: not all alterations performed
ORA-29702: error occurred in Cluster Group Service operation
ORA-29702: error occurred in Cluster Group Service operation
ERROR: error ORA-15032 caught in ASM I/O path

Uh-oh, that doesn’t look good. So I log into the ASM instance and try to see if the disks are OK:

SQL> select path, mount_status from v$asm_disk;
select path, mount_status from v$asm_disk
                               *
ERROR at line 1:
ORA-15032: not all alterations performed
ORA-29702: error occurred in Cluster Group Service operation
ORA-29702: error occurred in Cluster Group Service operation

Read the rest of this entry . . .

Just a quick announcements…

If you didn’t manage to attend my presentation, Oracle 11g ASM — The Evolution, during RMOUG or other conferences, you have a chance to see it online today. I’m doing it a web-cast at RAC SIG. It’s today, 4-Mar-10 at 12:00pm EST (9:00am PST).

Here are the slides from my presentation at RMOUG 2010.

I am not sure how much sense all this will make without my comments. We may do it in a webinar if there is sufficient interest. Regardless I will probably be doing it again at some point in the future.

Oracle ASM 11g Release 2 – The Evolution

Oracle Automatic Storage Management has proven to be one of the most widely adopted new features in Oracle Database 10g and it has been dramatically improved in the later 11g releases. This presentation will explain what changes are solved by ASM, how these challenges are solved, what barriers there are to ASM adoptions, and how 11g Release 2 addresses these barriers.

I shall say that the slides alone are not that helpful without my commentary but if you didn’t manage to attend it on one of the previous conferences, we will be releasing it as a webinar soon so stay tuned.

Update 9-Feb-10: Want to schedule a meeting with Pythian folks? See Pythian Events page.

I’m so much looking forward to the next conference in my schedule — RMOUG Training Days 2010. It would be only my second time I’m presenting at the RMOUG but it was enough to go there once to understand that it’s one of the top rated Oracle User Group conferences in the world. Some of the great speakers are presenting and registration fees are very low compare to other events of comparable quality. If your conference budget is low this year — that’s the conference you don’t want to miss!

Two of us from Pythian are going to speak at RMOUG Training Days 2010 that starts in just 4 week. I present the following session:

Alex Gorbachev: Oracle ASM 11g — The Evolution.
Oracle Automatic Storage Management has proven to be one of the most widely adopted new features in Oracle Database 10g and it has been dramatically improved in the later 11g releases. This presentation will explain what changes are solved by ASM, how these challenges are solved, what barriers there are to ASM adoptions, and how 11g Release 2 addresses these barriers.

My colleague, Christo Kutrovsky is presenting the following:
Read the rest of this entry . . .

Yes, it’s almost that time of the year when one of the best Oracle conferences in the world opens its doors to attendees in Birmingham — UKOUG Conference 2009: Technology & E-Business Suite. The lineup of speakers will be fantastic as usual and agenda is full of juicy bits — You will have usual troubles scheduling sessions to attend and hate to make compromises between presentations you want to see badly but that’s kind of problems you’d rather have at a good conference.

The past year was very eventful so I feel like I haven’t been at the UKOUG Conferences for years even though I did come to the UKOUG Conference 2008. This conference is something special for me — it’s the first conference I attended and presented on so it’s set the tone for the whole conferencing experience of my life and I’m very grateful for that! So far, I haven’t missed a single year since my first UKOUG conference and I hope I keep it this way for years to come.
Read the rest of this entry . . .