Jul 27
Linux dell, dmidecode, module, service tag No Comments
If you forget your Dell server module, if you also forget your service tag, how to get them quickly from OS command?
Try this command: dmidecode
It works for CentOS and RedHat Linux, and it also provides other detailed and useful hardware info about your server.
Jul 19
Linux alert email, monitor, nagios No Comments
I installed a Nagios based monitoring system on Ubuntu, Nagios uses /usr/bin/mail or /usr/bin/mailx to send the alert mail, so I manually installed ‘mailutils’ which contained ‘mailx’, but I found “Additional Info” contents cannot be displayed in the alert email, so I tried to install ‘bsd-mailx’ and replaced ‘/usr/bin/mailx’ with ’/usr/bin/bsd-mailx’ to send alert email, then the problem was fixed.
May 26
Performance Tuning aol pagetest, fiddler, firebug, httpwatch, ibm page detailer, web performance, yslow No Comments
Some times we need get to know how fast is my web page, and where the time goes to load each object? Does it set Etag, Expire?
So we need some tools to get those information and analyze the web page performance.
Here, I list some common tools which I use often.
1. Firebug+YSlow (* * * * *)
I think most of the web developers are familiar with Firebug and Yslow, don’t wanna talk more about it 
2. Httpwatch (* * * *)
It’s a commercial software, I use Httpwatch from version 4, basically, Httpwatch is good, it provides you most of the necessary information about the web contents, including header info, nice chart about where the time goes to load a object.
3. AOL Pagetest (* * * *)
It’s a freeware, provides most of the functions like Httpwatch, if you don’t wanna buy Httpwatch, AOL Pagetest is a good choice.
4. IBM Page Detailer (* * *)
Freeware, only provides some basic functions.
5. Fiddler (* * * *)
Fiddler is also a freeware, provides some powerful features, from my point of view, Fiddler is more like a sniffer.
6. CURL (* * * * *)
curl is the most popular web testing tool on Linux/Unix platform, also has a Windows version.
It’s hard to describe more details about each tool, just search them from Google and have a try.
Apr 26
Mac macbook, macos, mc737 No Comments
Apple released the new Macbook Pro this month, finally, I got my first Macbook Pro MC 373 today, I used Dell, Thinkpad before, but I have to say, I fall in love with Macbook now, it has so many wonderful designs and features, and the Mac OS operating system is so powerful and amazing.
I’m a newbie to Mac OS, there have many differences with Win, need some time to learn Mac OS.
Basic configuration list about my MC 737:
CPU: Intel core i7@2.66 G
Memory: 4G
Hard disk: 500G/5400 rpm(wanna buy a Hitachi 500G/7200 rpm to replace current Seagate, I don’t trust Seagate hard disk)
Video cards: Intel HD Graphics and NVIDIA GeForce GT 330M with 512MB
Mar 11
Performance Tuning, Site Architecture twitter, whale No Comments
Sometimes you may get a ‘Whale page’ from Twitter which indicates an error from Twitter server side.
If you’re interesting in the root cause and how Twitter engineers find and fix the problem, you may read the full story from this link: http://engineering.twitter.com/2010/02/anatomy-of-whale.html
Mar 11
Oracle 11g, new features, Oracle No Comments
Just found a good stuff about 11g new features especially for DBA and developers.
Overview:
1. Database Replay
2. Transaction Management
3. SQL Plan Management
4. SQL Access Advisor
5. RMAN
6. Automatic Storage Management
7. Caching and Pooling
8. SecureFiles
9. Data Guard
10. Data Warehousing and OLAP
11. Partitioining
12. Schema Management
13. SQL Performance Analyzer
14. PL/SQL: Efficient Coding
15. Security
16. Manageability
17. SQL Operations: Pivot and Unpivot
18. Resiliency
19. Pl/SQL Performance
20. Others
For more details, you may download the full version from http://www.oracle.com/technology/pub/articles/oracle-database-11g-top-features/oracle-database-11g-top-features.zip
Feb 25
Oracle 11g, aud$, upgrade No Comments
If you’re going to upgrade your 10g database to 11gR2, some notes here may be helpful for you.
1. Initial parameters
background_dump_dest
core_dump_dest
user_dump_dest
Those three parameters have been deprecated in 11g, even we set compatible to 10204.
Instead, they’re replaced with parameter diagnostic_dest
Also I found:
_lgwr_async_io = true
This is also invalid in 11gR2.
2. Listener log file format
In 11gR2, the default listener log file format is XML, but how to use original text format log file? You can add one line in listener.ora configuration file.
DIAG_ADR_ENABLED_LISTENER_SID=OFF
Here, SID is your own SID.
3. Some ways to speed up 11g upgrade performance
Create dictionary statistics right before the upgrade.
SQL> exec dbms_stats.gather_dictionary_stats;
If upgrade from 10g or 11g, purge the RECYCLEBIN
SQL> purge DBA_RECYCLEBIN;
SYS.Aud$
In my previous post:http://www.isoracle.com/?p=36 which was 9i->10g upgrade, Oracle was running this update statement:
UPDATE aud$ SET ntimestamp# = SYS_EXTRACT_UTC (CAST(timestamp# AS TIMESTAMP WITH TIME ZONE)) WHERE ntimestamp# IS NULL
But this time, 10g to 11gR2, Oracle also updates aud$ when you execute catupgrd.sql, the update statement is:
UPDATE SYS.AUD$ SET dbid = 4120164022 WHERE dbid IS NULL AND rownum <= 10000;
In 10g, the values of DBID column in aud$ are all NULL, but in 11g, Oracle wants set the current DBID value for aud$
Also in 11g, Oracle adds one new column OBJ$EDITION by comparing with 10g.
From my test, it took 2 hours to finish above UPDATE statement which aud$ size is about 960MB with 8.3 million rows, that’s unacceptable especially for a production DB upgrade.
Solution:
1. If data in aud$ is not important to you, you can just export the aud$ for backup and then truncate it before upgrade.
2. If you need keep those data, you can manually run that UPDATE statement before issuing catupgrd.sql, after finish the UPDATE statement, and then run catupgrd.sql, from my test, Oracle will not run that update statement again during the catupgrd.sql execution if you have already manually set DBID for aud$.
Feb 01
Now, we cannot find the link on www.mysql.com to download the community version, that’s so bad!
Some of my friends asked me where to download the community version? Well, although the link was removed from the homepage, but we can still find the community version from http://dev.mysql.com or http://www.mysql.org
Jan 29
Oracle ora600, Oracle, standby No Comments
Last night, I found one of the standby delay is abnormal, from alert log, I found ORA-600 error in the alert log:
Thu Jan 28 02:14:11 2010
Errors in file /path/to//udump/joe_ora_13159.trc:
ORA-12805: parallel query server died unexpectedly
Thu Jan 28 02:14:11 2010
Errors in file /path/to//udump/joe_ora_13159.trc:
ORA-00600: internal error code, arguments: [krd_check_slaves_2], [], [], [], [], [], [], []
Thu Jan 28 02:42:53 2010
Errors in file /path/to//udump/joe_ora_13159.trc:
ORA-00600: internal error code, arguments: [krd_check_slaves_1], [], [], [], [], [], [], []
ORA-00600: internal error code, arguments: [krd_check_slaves_2], [], [], [], [], [], [], []
Cause from Metalink:
The ORA-600 [krd_check_slaves_1] is raised on the cleanup of the recovery slaves.
The Coordinator (the session which intiated the recovery) is waiting for the Parallel Query slaves, who participate in the recovery, to stop.
If they are not stopped after 900 sec (15 min), the ORA-600 [krd_check_slaves_1] is raised.
Bug 5084496 is very much related but is handling a look-a-like issue for a standby database parallel recovery.
A new bug 5759272 – PARALLEL RECOVERY FAILS WITH ORA-00600 [KRD_CHECK_SLAVES_1] has been opened for this issue.
Workaround:
Bounce the standby database.
Sep 05
Site Architecture architecture, key-value, scalability, Storage No Comments
Just find a good stuff about scalable storage system, especially Key-Value storage system part.
You can download the PDF or PPT format presentation from author blog.
Contact Way:
Email&Gtalk:
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http://twitter.com/dbajoe
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