In my last post, I looked at the effect of the Exadata smart flash logging. Overall, there seemed to be a slight negative effect on median redo log sync times. This chart (slightly different from the last post because of different load and configuration of the system), shows how there’s a “hump” of redo log syncs that take slightly longer when the flash logging is enabled:
But of course, the flash logging feature was designed to improve performance not of the “average” redo log sync, but of the “outliers”.
In my tests, I had 40 concurrent (more...)
There have been a couple of posts we've seen lately about expectations of an Exadata X3-2 and X3-8 release at Oracle Open World 2012. I mentioned in my previous post about the possible release of an X3-2 1/8th rack configuration. I had guessed that this would be similar to the old V2 basic system that would include one compute node, one storage server, and one infiniband switch - all placed in your own rack. It sounds like I was a little bit off from this original idea.
Oracle has stopped taking orders on X2-2 and X2-8 hardware, and we have (more...)
With only a month away from Larry Ellison's keynote at Oracle OpenWorld 2012, I thought that I would make a couple of wild guesses about new products that may or may not get announced this year. I'll lump them into a few educated guesses and wild conjecture. Insert standard blogging disclaimer (please read this part, Oracle lawyers):
Everything contained in this blog post is pulled from publicly available information and conclusions drawn from products that are currently available outside of Exadata. None of this information comes from within Oracle - not that Oracle would be willing to give me any (more...)
Just a quick note about change in the way the compute nodes are patched starting from version 220.127.116.11.1. For earlier versions Oracle provided the minimal pack for patching the compute nodes. Starting with version 18.104.22.168.1 Oracle has discontinued the minimal pack and the updates to compute nodes are done via Unbreakable Linux Network (ULN).
Now there are three ways to update the compute nodes:
1) You have internet access on the Compute nodes. In this case you can download patch 13741363, complete the one time setup and start the update.
I’ll be speaking at the Enkitec Extreme Exadata Expo (E4), August 13-14 in Dallas Texas (you can also attend virtually). They’ve recruited some of the top names from community including keynote speaker Andrew Mendelsohn, Arup Nanda, Cary Millsap, Jonathan Lewis, Karen Morton, Maria Colgan, Kerry Osborne and Tanel Põder. I left a lot of names off the list, many of which you probably [...]
Exadata storage software 22.214.171.124 introduced the Smart flash logging feature. The intent of this is to reduce overall redo log sync times - especially outliers - by allowing the exadata flash storage to serve as a secondary destination for redo log writes. During a redo log sync, Oracle will write to the disk and flash simultaneously and allow the redo log sync operation to complete when the first device completes.
Jason Arneil reports some initial observations here, and Luis Moreno Campos summarized it here.
I’ve reported in the past on using SSD for (more...)
Recently i got a question from an Exadata customer what would happen if you would forget to relink the oracle for IPC RDS use for just one home. Would Oracle be smart enough to fall back on UPC for the complete RAC database? Time to do a little test and find out what will happen here:
First lets see how IPC communication between the nodes is done right now. We can use skgxpinfo to see how it is linked since version 126.96.36.199.0:
[oracle@dm01db01 [dbfs1] ~]$ dcli -g dbs_group -l oracle /u01/app/oracle/product/188.8.131.52/dbhome_1/bin/skgxpinfo
I’ll be co-speaking with Randy Johnson (one of the authors of Expert Oracle Exadata) at E4 to share about the war stories and detail on a bunch of technical stuff on a Peoplesoft and BIEE consolidation project we had on one of our clients. See the abstract below:
Randy Johnson & Karl Arao
A PeopleSoft & OBIEE Consolidation Success Story
In today’s competitive business climate companies are under constant pressure to reduce costs without sacrificing quality. Many companies see database and server consolidation as the key to meeting this goal. Since its introduction, Exadata has become the obvious choice for (more...)
Last week I had a lengthy post at oracle-l that tackles Calibrate IO, Short Stroking, Stripe size, UEK kernel, and ASM redundancy effect on IOPS Exadata which you can read here
followed by interesting exchange of tweets with Kevin Closson here (see 06/21-22 tweets) which I was replying in between games at UnderwaterHockey US Nationals 2012 which we won the championship for the B division I have my awesome photo with the medal here
This post will detail on the ASM redundancy/parity effect on IOPS… if… by changing the ASM redundancy (external, normal, and high) will it decrease the workload (more...)
This blog posting is very much a follow on from the previous entry on how data compressed with Exadata HCC compression behaves under changing table definitions. Many thanks to Greg Rahn for the comments on the previous blog entry on a simple mechanism for determining whether the compression level has changed or not.
In this blog posting we add a column to an HCC compressed table and we observe whether the number of blocks in the table changes or not.
As Greg stated in the comments on the previous blog entry, we have 3 possibilities for adding a column:
- add (more...)
While everyone is aware of the issues of mixing EHCC compression and OLTP type activities, I had a customer who was interested in finding out what happens upon adding a column to a table that has EHCC compression enabled on it.
As I could not see any definitive statements in the documentation on this particular scenario I ran up some tests to see the behaviour.
First of all they are using partitioning by date range, so we create a partitioned table:
SQL: db01> create table t_part (
created date )
partition by range (created)
( partition (more...)
I recently had the chance to create some diskgroups on an Exadata box outside the standard installation procedure, while this is not necessarily Exadata specific, I thought the technique of using ASMCA silently on the command line to create the diskgroups was sufficiently novel for a short blog posting. If for nothing else but to remind myself on how to do this in future.
This example uses the disks presented from a quarter rack exadata system and creates a diskgroup called DATA01:
asmca -silent -createDiskGroup -diskGroupName 'DATA01' -diskList o/192.168.10.14/DATA01_CD_00_cel01,o/192.168.10.14/DATA01_CD_01_cel01,
Had a great day at the UKOUG Exa.. Day yesterday. I was happy by and large with how my presentation went, it was a bit irritating having some technical issues with laptops and projectors, but hopefully the audience was entertained enough to not let that have annoyed them too much. I’ve included a link to the powerpoint of the presentation, you really need to read the notes to gain an understanding of what I was trying to say!
Apologies that it is a near 7MB download, but I’d be happy to answer any questions you may have on it, (more...)
Tuning has always being good fun and something like a challenge for me.
From time to time we are being asked to find out why something did run slow while you are sleeping; answering this question is, in most cases, a challenge.
My batch did run slow last night, can you let us know why? Or why did this query run slow? Are questions we, as DBAs, have to answer from time to time.
Oracle has provided us with many tools to dig out information about past operations. We have EM, AWR, ASH, dba_hist_* tables, scripts (more...)
With the 184.108.40.206.0 release of the Exadata storage server software (and providing you are at least at 220.127.116.11 BP11), you will have the opportunity to utilise Exadata Smart Flash Logging. I thought I’d take a look at how much (if any) improvement this feature would provide to a busy production environment.
Have a look at this blog entry on Exadata Smart Flash Loggin by Luis Moreno Campos for an introduction on how it works. Basically you now issue two writes, 1 to flash 1 to your disk based redo logs, fastest write is (more...)
Hybrid Columnar Compression (HCC) is a new awesome feature in Exadata that helps in saving a lot of storage space in your environment. This whitepaper on Oracle website explains this feature in detail. Also Uwe Hesse has an excellent how to use all this post on his blog. You can see the compression levels one can achive by making use of HCC. It is very simple to use feature but one needs to be aware of few things before using HCC extensively as otherwise all your storage calculations may go weird. Here are few of the things to keep in (more...)