Oracloid Blog

UKOUG 2006 is over and I was planning to finally provide a bit more details about it especially now when wireless internet is usable - during the conference there were way too many people connected and it was difficult to get in. It’s really nice that they left a Wi-Fi access point working after conference closing.

While sitting around “Oak” Table (or how it’s called this year - Bloak table), I got a reminder that today is the last day to send IOUG abstracts. Since I planned to submit an abstract there - I rushed in and filled out two proposals based on responses I’ve got from my UKOUG presentations.

One abstract is about block change tracking internals. I saw that people were interested and Jonathan Lewis even mentioned it on his blog. So I thought that if this sir enjoyed it then others must be interested as well. I will probably redesign it a bit and remove some details but cover few more things that are unknown so far. Thanks to Tanel’s presentation on advanced research techniques, I have few ideas where to look now.

The second presentation will be (if accepted) on Extensibility of Grid Control. I saw that there was interest but I packed way too much in the presentation and rushed through it. So my plan is to cut some bits from it and organize a demo instead. I learned quite a bit from my first presenting experience so next time I should be even better. ;-)

Now the most important message of this post… I know the story behind this picture taken by the Hubble telescope. :-) Do you?
I’ll give you a hint - it’s a member of the OakTable Network on this picture - nothing to do with Uranus. By the way, Anjo Kolk is a very nice and entertaining guy as well as bunch of others I’ve met here at UKOUG. If you really want to know the secret of that picture - ask Anjo. I’m sure he’ll be happy to provide some insightful details.

By the way, he had quite interesting presentation “CPU Stories” and showed how to decide between faster CPU’s or more CPU’s. Actually, I’m really impressed that he was able to deliver it so well after such a long night (again!).

Since I started to speak about the last night, I can tell you that it was very entertaining and lots of fun. I collected quite a few nice photos and should post soon. Interesting fact is that this morning everyone (except me) knew that I went to bed at 5:20. How come? I’ll go and check if there is a hidden camera in my room. To get you guys jealous - I’m going to a nice Indian restaurant today. :-P

Here is another detail from the evening. The name of this beautiful detail is Hana.

Hana, you promised to read my blog. The picture of you that we have is really poor in quality. Please send us a good one! Me and Anjo are looking forward to it!

PS: Hm… is my darling reading this blog?

Since all my presentations were over at the day 1, I’m now relaxing and enjoy others’ sessions. Interesting was the Anti-Tuning RAC round-table with conclusion that more or less majority is running RAC because they have way too much money/time/hardware/name it. No surprise if you know who moderated it.

The best part was in the evening even though I was stupid enough to sped £35 on the UKOUG organized dinner - let’s say, the food was good but I expected something more from that. So after closing at about 11pm I popped into Jury’s Inn bar and all the usual suspects were there. By that time some more “Oakers” appeared as their dinner was over. Anyway, Jury’s Inn bar was empty in few hours and the next stop was Hyatt bar Pravda (translated from Russian as “truth”, by the way). The bar itself was… how can I put it… not good - no Guinness and way too expensive. I still had good time there and they threw us out by 4am.

Today I was at the conference by 9am and was feeling even more fresh than the previous day. I think that moderate amount of Guinness has positive impact!

I should mention that I attended an excellent presentation from Steve Shaw (creator of Hammerora) and I had a nice chat with him. He’s done quite a few improvements to Hammerora and the new version is coming soon. Good job!

UKOUG Day 1 backwards

It was a lo-o-ong day and I was absolutely plasted by the time I got to bed… we finished after 3 am in the Jury’s Inn Hotel Bar. It was whiskey that we finished with - pretty good one. Before that I enjoyed Blogger Meetup at All Bar One. I believe there were about 4 meetings there or so and they all ended up as one networking event. Thanks to Doug for “infamousing” me. But he’s done good job describing this part of the evening. The last boy scouts at All Bar One:

Going further backwards… I can’t say a lot about presentations I went to as my head was completely empty after my 3 sessions. Last session was on Oracle Streams CDC - I am still not sure what the added value of CDC compare to regular Streams functionality. But the truth is I couldn’t think about anything else but Guinness at that point…

I really enjoyed Anjo’s talk on SAN Stories - content was exactly for my state of mind at that point - easy and understandable. Before that I tried to Understand Shared Pool Memory Structures but, first, I was already tired and, second, material wasn’t deep enough to deepen the understanding but rather a rush through it. I guess you need at least a day to cover that topic. What I remember well is that on one slide a potential solution for shared pool problems was… get this - RAC!

Tracing PX Slaves was a familiar area so it was quite insightful even though I wasn’t in the best shape already…

The last of my own three sessions was on block change tracking internals. This was probably the best even though I couldn’t cover the subject completely - still quite a few unknown things around it. Before that - lunch with only one comment - how can you eat standing???

Two other presentations from myself… The second is about refreshes and I think it was not bad. I finished in 45 minutes sharp without actually any time for QA but it was lunch time after that so no issues. The session on OEM Extensibility was probably the worst even though I was the most comfortable with it - I just packed too much into one hour and had to rush through it. That worked, though - I finished 10 minutes earlier leaving enough time for QA but there were only few questions. I think it was just too much information to get into and digest “online”.

Opening technical keynote was from Tom Kyte – very insightful speech on 11g or whatever letter it will be.

And the day started with panic – presenting first time to a crowd. It wasn’t that difficult as I figured in the end.

I feel it’s going to be good fun - I’m only on my way to UKOUG 2006 but it’s already an adventure. I had the flight Ottawa -> London booked over Washington where I should have had 2 hours for connection. Registration went fine almost until the very end (had to give away my water though and Babette was finishing here coffee on the way) but at the US customs I’ve got the problem. Apparently, there is a new rule for transit passengers - they suspended permission for all international connections without a transit visa. It used to be so that transit passengers stay in the terminal and no need for any kind of visa. Not anymore and it’s valid “until further notice” as stated in their systems.

Being stubborn enough (the common quality here at Pythian ;-) and I’m not going to skip the fun just because of some stupid immigration rules so… I had to go back to the check-in counter, get my baggage and re-book my ticket to avoid a stopover in the States. They re-booked me on the direct flight Ottawa-London and that cost me only $200 after some negotiations (originally $2000+) and 2 hours of my time early in the morning. Unfortunately, I’ve got split up with Babette and I hope she is fine on her own there.

Babette, if you read this post by any chance, I should be in the Hotel on Monday at about 11:00. I also left you a message at the receptions desk.

Back to the UKOUG - I have three sessions there. These are first three right on Tuesday after the Opening Technical Keynote by Tom Kyte:

• Extending Oracle 10g Grid Control - New Metrics, Targets and Plugins - 11:00-12:00, Hall 6
• Refreshing Test Databases Using Oracle Transportable Tablespaces and Veritas Storage Checkpoints - 12:10-12:55, Hall 6. Here is the surprise - I’ll show how to do the same with ZFS. I’m really excited about that.
• Oracle 10g Change Tracking Inside Out - 13:50-14:00, Hall 9. Consider this if you want to get down to X$ tables and tracing.

Babette has two presentations the same day:

• Moving from Oracle Names to Oracle Internet Directory - 11:00-12:00, Hall 11b

• Oracle 10g Data Pump 101 - 17:50-18:35, Hall 5

See you there! I’m off to my flight. Again…

While reviewing some material in advance of my presentation at UKOUG Conference 2006, I found an interesting change in RMAN behavior in Oracle 10g.

The difference is in the way RMAN handles the case when an incremental level 1 backup is taken without an available level 0 backup. This probably won’t affect anyone much, but I found it interesting. And actually, there are scenarios in which it might cause issues.

Pre-10g behavior (also in effect in 10g by setting compatibility to < 10.0.0) produces a level 0 backup in case incremental level 1 is run without level 0.

Oracle 10g behavior is to take a level one backup assuming that a checkpoint SCN of the last level 0 backup is the datafile creation SCN.
It doesn't look like a big deal but imagine the following scenario (I didn't test it - just thinking logically):
Incremental backup strategy is "standard".
Sunday - level 0 backup.
Monday-Saturday - level 1 cumulative.

Now, imagine that on Monday there is an issue and the backup is not available anymore -- either it's lost, or recovery with resetlogs has been done. The next incremental backup stores all the blocks, so we have a valid backup -- no problem here.

However, the keyword in the backup strategy is cumulative. The next incremental level 1 cumulative backup still doesn’t find the level 0 backup and again copies every block in the database. This continues until the next level 0 backup is taken on Sunday. Assuming DBAs are always unlucky, the backup destination tapes will fill up before the incremental level 1 backup is run. Typical, isn’t it?

How can we avoid this? By taking the level 0 backup first time and not regular level 1.

Note that “differential” (when no cumulative keyword is specified) incremental backup won’t cause any issues, as it takes only those blocks changed since the last incremental backup.

Recently we’ve had quite a few migrations to 10g Release 2 and several times been hit by one issue – some users consistently get locked with status LOCKED(TIMED). One good example is with the DBSNMP and SYSMAN users, but more important are locked production accounts.

It turned out that the FAILED_LOGIN_ATTEMPTS attribute for the DEFAULT profile has been changed in 10.2.0.2 (actually 10.2.0.1 and above) from UNLIMITED to the value of 10. Well, that’s good from security point of view. On the other hand, this is really dangerous, especially during or after migrations while chances are high that some process will try to connect with wrong credentials. This can easily end up with a service outage because an application can’t connect.

One way to resolve it is to change the DEFAULT profile. However, I would recommend leaving it 10 by default and, instead, create a new profile and assign the critical production users to this profile:

CREATE PROFILE DEFAULT_10GR1
    LIMIT FAILED_LOGIN_ATTEMPTS UNLIMITED;
ALTER USER [USERNAME] PROFILE DEFAULT_10GR1;

The next step should be to review this policy with your security officer. By the way, this must be a substantive discussion – a production DBA should be keen to avoid service outages by any means, while a security officer’s priority is preventing unauthorized access.

PS: Interesting that the issue with the DBSNMP account is supposed to be resolved by creating a special profile – MONITORING_PROFILE. There are few notes on Metalink about it like 336629.1.

PPS: Just now I found out that Laurent has already mentioned that a while ago (and thanks to him) the change was finally documented in the Readme note for Oracle 10.2.