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Interlude

Having the right mental model of how window functions operate goes a long
way toward recognizing when and how to apply these functions that can seem
almost magical in the expressive power.



Read the full post at www.gennick.com/database.

Interlude

Having the right mental model of how window functions operate goes a long
way toward recognizing when and how to apply these functions that can seem
almost magical in the expressive power.



Read the full post at www.gennick.com/database.

Internal Server Error – Contact Your System Administrator

December 6, 2011 The Oracle OTN forums changed a bit a year or two ago, and in the process I stopped receiving email notifications when new entries were added to discussion threads.  The absence of email notifications was not a significant loss, although at times it is a bit interesting to see how a post in some of [...]

Was the Oracle UK logo Blue back in 1991?

I think I might be going mad. I was sure that when I joined Oracle UK back in 1991 that the massive “Oracle” sign above the main office on “The Ring” in Bracknell was blue. It was the building that looked like a load of cubes balanced on each other.

As I remember it, the office stationary had “Oracle UK” on it in blue and my business cards were similarly coloured. I can’t find any 20 year old stationary to prove it and I owe Bryn Llewellyn a bottle of wine if I turn out to be wrong.

I’m sure I also remember fellow consultants joking in around 1993, when the annual bonus was particularly poor, that it was due to all the money spent going from blue to red stationary and signs when our UK identity was absorbed into the parent beast…

Recent SPARC T4-4 TPC-H Benchmark Results. Proving Bandwidth! But What Storage?

On 30 November, 2011 Oracle published the second result in a recent series of TPC-H benchmarks. The prior result was a 1000GB scale result with a single SPARC T4-4 connected to 4 Sun Storage F5100 Flash Arrays configured as direct attached storage (DAS).  We can ascertain the DAS aspect by reading the disclosure report where we see there were 16 SAS host bus adaptors in the T4-4. As an aside, I’d like to point out that the F5100 is “headless” which means in order to provision Real Application Clusters storage one must “front” the device with a protocol head (e.g., COMSTAR) such as Oracle does when running TPC-C with the SPARC SuperCluster. I wrote about that style of storage presentation in one of my recent posts about SPARC SuperCluster. It’s a complex approach, is not a product, but it works.

The more recent result, published on 30 November, was a 3000TB scale result with a single SPARC T4-4 server and, again, the storage was DAS. However, this particular benchmark used Sun Storage 2540-M2 (OEMed storage from LSI or Netapp?) attached with Fibre Channel. As per the disclosure report there were 12 8GFC FC HBAs (dual port) for a maximum read bandwidth of 19.2GB/s (24 x 800MB/s). The gross capacity of the storage was 45,600GB which racked up entirely in a single 42U rack.

So What Is My Take On All This?

Shortly after this 3TB result went public I got an email from a reader wondering if I intended to blog about the fact that Oracle did not use Exadata in this benchmark. I replied that I am not going to blog that point because while TPC-H is an interesting workload it is not a proper DW/BI workload. I’ve blogged about that fact many times in the past. The lack of Exadata TPC benchmarks is in itself a non-story.

What I do appreciate gleaning from these results is information about the configurations and, when offered, any public statements about I/O bandwidth achieved by the configuration.  Oracle’s press release on the benchmark specifically called out the bandwidth achieved by the SPARC T4-4 as it scanned the conventional storage via 24 8GFC paths. As the following screen shot of the press release shows, Oracle states that the single-rack of conventional storage achieved 17 GB/s.

Oracle Press Release: 17 GB/s Conventional Storage Bandwidth.

I could be wrong on the matter, but I don’t believe the Sun Storage 2540 supports 16GFC Fibre Channel yet. If it had, the T4-4 could have gotten away with as few as 6 dual-port HBAs. It is my opinion that 24 paths is a bit cumbersome. However, since it wasn’t a Real Application Clusters configuration, the storage network topology even with 24 paths would be doable by mere mortals. But, again, I’d rather have a single rack of storage with a measly 12 FC paths for 17 GB/s and since 16GFC is state of the art that is likely how a fresh IT deployment of similar technology would transpire.

SPARC T4-4 Bandwidth

I do not doubt Oracle’s 17GB/s measurement in the 3TB result. The fact is, I am quite astounded that the T4-4 has the internal bandwidth to deal with 17GB/s data flow. That’s 4.25GB/s of application data flow per socket. Simply put, the T4-4 is a very high-bandwidth server. In fact, when we consider the recent 1T result the T4-4 came within about 8% of the HP Proliant DL980 G7 with 8 Xeon E7 sockets and their PREMA chipset . Yes, within 8% (QphH) of 8 Xeon E7 sockets with just 4 T4 sockets. But is bandwidth everything?

The T4 architecture favors highly-threaded workloads just like the T3 before it. This attribute of the T4 is evident in the disclosure reports as well. Consider, for instance, that the 1TB SPARC T4 test was conducted with 128 query streams whereas the HP Proliant DL980 case used 7. The disparity in query response times between these two configurations running the same scale test is quite dramatic as the following screen shots of the disclosure reports show. With the HP DL980, only query 18 required more than 300 seconds of processing whereas not a single query on the SPARC T4 finished in less than 1200 seconds.

DL980:

SPARC T4:

Summary

These recent SPARC T4-4  TPC result proved several things:

1.    Conventional Storage Is Not Dead. Achieving 17GB/s from storage with limited cabling is nothing to sneeze at.

2.    Modern servers have a lot of bandwidth.

3.    There is a vast difference between a big machine and a fast machine. The SPARC T4 is a big (bandwidth) system.

Finally, I did not blog about the fact that the SPARC T4 TPC-H benchmarks do not leverage Exadata storage. Why? Because it simply doesn’t matter. TPC-H is not a suitable test for a system like Exadata. Feel free to Google the matter…you’ll likely find some of my other writings stating the same.

Filed under: Exadata, Exadata Database Machine, oracle, Oracle TPC-H, SPARC Supercluster Tagged: Xeon E7 Performance

Mining EMGC Notification Alerts

The past few days, I’ve been troubleshooting an email alerting problem on an EMGC 11.1 install on a client site.
But this troubleshooting also includes setting up my own email server and reproducing the problem http://karlarao.tiddlyspot.com/#EmailNotificationsNotSending
Watching/digging on the EM web based interface is tedious so I devised a way to just mine on the MGMT views… thanks to the MOS 421499.1 EMDIAG REPVFY Kit – which is a good source for mining the EMGC repository.

This simple query from the MGMT views will output something like this


SELECT t.target_name, t.target_type,
       substr(s.message,1,50) , substr(l.message,1,11) emailed,
       TO_CHAR(s.load_timestamp,'DD-MON-YYYY HH24:MI:SS') loaded,
       s.severity_guid,
       TO_CHAR(a.timestamp,'DD-MON-YYYY HH24:MI:SS') annotated,
       TO_CHAR(l.timestamp,'DD-MON-YYYY HH24:MI:SS') logged
FROM    mgmt_severity s, mgmt_targets t, mgmt_annotation a, mgmt_notification_log l
WHERE   
       s.target_guid     = t.target_guid
  AND  s.severity_guid   = a.source_obj_guid (+)
  AND  s.severity_guid   = l.source_obj_guid (+)
  -- AND a.annotation_type = 'NOTIFICATION'
  -- AND lower(s.message) like '%tablespace%percent%'
  -- AND lower(t.target_name) like '%mta%'
  -- AND s.severity_guid = 'B33A7C7DF7A0293CE040460A22EA5E84'
ORDER BY s.load_timestamp desc;

and with this data you can actually do filters.. lets say search for the tablespace alerts test cases that I created. This shows that it reached the metric threshold but it did not send the email because the “Emailed” column shows as as “null”

another thing you can do is have a query that shows monthly count of tablespace alerts that were sent or not sent..


select count(*), TO_DATE(loaded,'MON') loaded, emailed from (
SELECT t.target_name, t.target_type,
       substr(s.message,1,20) , substr(l.message,1,11) emailed,
       TO_CHAR(s.load_timestamp,'MON') loaded,
       s.severity_guid,
       TO_CHAR(a.timestamp,'DD-MON-YYYY HH24:MI:SS') annotated,
       TO_CHAR(l.timestamp,'DD-MON-YYYY HH24:MI:SS') logged
FROM    mgmt_severity s, mgmt_targets t, mgmt_annotation a, mgmt_notification_log l
WHERE   
       s.target_guid     = t.target_guid
  AND  s.severity_guid   = a.source_obj_guid (+)
  AND  s.severity_guid   = l.source_obj_guid (+)
  AND  lower(s.message) like '%tablespace%percent%'
ORDER BY s.load_timestamp desc
)
group by loaded, emailed
order by loaded desc;


and for sure there’s much more things you can do with all of these filters

— AND a.annotation_type = ‘NOTIFICATION’ <– annotated as NOTIFICATION
— AND lower(s.message) like ‘%tablespace%percent%’ <– search string on the alert message
— AND lower(t.target_name) like ‘%mta%’ <– search string on the target name
— AND s.severity_guid = ‘B33A7C7DF7A0293CE040460A22EA5E84′ <– search the alert ID

That’s it for now.. hope I’ve shared you some good stuff :)





SSH root attacks on the rise

This is not directly Oracle related, but probably still of interest.

SSH Password Brute Forcing may be on the Rise

Out of curiosity I pulled the ssh login attempts from /var/log/messages an internet facing server, and the data  corresponds to what was shown in the article.

What was interesting was that all ssh attempts that I saw were for root.  In the past when I have looked at these there are a number of different accounts being attacked, but now the attacks are all for root.

UKOUG 2011: When sessions attack…

Just finished my session. What a nightmare…

I was surprised anyone turned up as it was a late change to the schedule and there were some great sessions going on at the same time. Check out the photo.

It was kinda OK, until I got to the demo, which I screwed up. That was really disappointing because it really was the crux of the session. I thought I saw the issue and tried to salvage it, but it failed again so I gave up and moved on. I would like to say it was an OK recovery from a disastrous demo, but that would be a lie. Flipping crap.

Quite annoyed with myself because I know why it got screwed up. When I was in Bulgaria somebody asked me a question and I messed with the demo to prove a point, but forgot to repair it afterwards. Of course, it works again now that it’s too late. :(

There seemed to be some real interest in the technology and I assured people that the demo screwing up was noting to do with the tech, it was totally my fault.

So not the best showing I could have put in. I think it is summed up nicely by this tweet,

“session clone db is a mess”

Nuff said!

If anyone wants to see the running demo, drop me a line on twitter (@oraclebase) and I’ll meet you and show it working. If not, check out the article here.

Cheers

Tim…




I’ve Been Made an Oracle Ace.

I tried to come up with a witty title but after only first day at the UKOUG conference, OakTable Sunday, my brain is already a little fried…

So yes, last Friday evening I received an email from Oracle Corp informing me I had been nominated for and been accepted as an Oracle Ace. I’d just accidentally blown away some of my slides for a presentation I’m giving this week and I was a bit weary of the whole community thing, so it gave me a real lift. It would have given me a lift anyway, but the timing seemed very nice – it re-invigorated me and it also meant that I could now mention my Ace-dom at conference. Endlessly. I never won prizes at school so this sort of thing goes to my head. Sorry.

Of course, my wife keeps my feet on the ground. I wandered over to the kitchen to tell her…
“Hey, Sue, I’ve just been made an Oracle Ace!”
“That’s nice dear – empty the cat’s litter tray while you are there, it stinks”.
*sigh*

It means a lot to me to be an Oracle Ace. I’m not going to pretend to be all unconcerned over it or say “oh no, not me, I am not worthy of that” like I did {and still do} over being a member of the OakTable. In the last 10 or 12 years I’ve done a lot for Oracle Corp (some of which is public, some of which was working with Oracle on testing things and talking to other Oracle customers about getting the most out of the technology) and also with the UK oracle community so I kind of feel the Acedom is an earned reward for that. But I am also very grateful for it, it is still a relatively rare accolade and Oracle have to feel that you are benefiting the wider community to bestow the award on you.

Being an Ace has already had some impact on me. I met my friend Neil Chandler at the conference, he is the person who nominated me (Oracle tell you who nominated you). “Hey, Neil, due to you I’ve been made an Oracle Ace! Thank you very much!”. “Great Martin, well deserved – so let’s have beers tonight and you can thank me properly”. “Errrr, I’ve been invited to an Ace meal this evening….”. “Well get you! Only just an Ace and too good for us commoners huh? You’ve changed, You’ve really changed….”

The Ace meal was good and much appreciated but I ate too much spicy stuff and boy I’ve got bad indigestion {and more unpleasant symptoms} now.

So it seems, based on evidence so far, Being an Ace loses you friends and makes you feel unwell. This is not what I was expecting….

:-)

{It’s OK, Neil and I had beers before the meal and he forgave me in the end – on the condition I provide him with more beer soon}

UKOUG 2011: Day -1

I missed the OakTable day because it was the 10th birthday party of nephew number 1, but I did make it back to Birmingham in time for the ACE dinner. Mark Rittman provided evidence of my presence here. I was already full of cake and trifle before I arrived, but the waitress didn’t seem to understand, “I’m not eating”, so I was *forced* to stuff myself again. :) Many thanks for the organizers of this event.

I mentioned in a previous post Oracle RAC was not for newbies. Although the commenters seemed to agree with me, a couple of people suggested I was being a bit elitist and if you read the manuals it is all fine. I found out last night that Connor McDonald is now presenting his “Year in Purgatory” talk at UKOUG. I saw this session in Perth and I can’t recommend it enough. As well a being a great show, it highlights just how difficult managing RAC can really be. If you have, do or plan to work with RAC you should see this session, then decide if I’m wrong about the complexity of RAC. Check out the changes to the agenda…

I better get off my ass and head down to the conference. It’s been a while since I’ve driven into the city center at this time in the morning. I hope the traffic is not as bad as it used to be. :)

Remember, I’ve got a session at 11.05 today. Once again, check the changes to the agenda.

Cheers

Tim…