Archive for March 2012
About 1,000,000,000 of them in this amazing composite photograph of the Milky Way. Taking 10 years to make and using 2 telescopes (to get a view from North and South hemispheres) it combines the UKIDSS/GPS sky survey acquired by the UK Infrared Telescope in Hawaii with the VVV survey data acquired by the Vista telescope in Chile.
This zoomable image is truly magnificent; to get an idea of scale of the number of visible stars, if you count them at a rate of 1 per second it will take you well over 30 years to count them all.
ITIL (Information Technology Infrastructure Library) does work. It works very well and is becoming more and more widely adopted, but does not always work the way that management thinks it works.
The basic premise of ITIL is to put structure and process around the business of running IT. It is a collection of guiding principles which, if appropriately adopted into a company will help run the IT function in a reasonable process-driven fashion. It’s largely common sense, which helps.
However, after lots of experience with all of the different aspects of ITIL I have decided that it doesn’t really work the way management think it does. This is especially relevant to Change Management.
The premise behind Change Management is that technical staff are prevented from making non-Standard changes to the IT systems without prior authorisation from all relevant stakeholders.
Where this falls down is 2 fold.
- The definition of Standard change needs to be very carefully identified, documented and locked-down. It never is, leading to techies making personal decision about what constitutes standard change. This definition is always enthusiastically elastic, until something snaps when it will become frustratingly draconian (for a while).
- The stakeholders rarely understand the nature and true impact and risk of the changes taking place, so the CAB must accept the opinion of the techie (see above). The net result of a Change Advisory Board (CAB) is to authorise the technical staff to make change whilst putting the burden of responsibility for the change onto the management. Not the techie. If the changes goes wrong, then it is fault of the approving manager for not assessing the risk correctly, or for approving the change to take place at the wrong time or in the wrong way. However, the techie gets off scott free in all of this.
As long as the process is followed, we can get away with murder.
I’ve been spending some time working in Apex recently, building a small app to draw together the monitoring of application and infrastructure components into a single easy-to-visualise tool. As part of that, I wanted to be able to read and report on the alert log. Traditionally, that would have meant creating an external table to point to the alert log and reading it that way, with lots of string manipulation and regular expressions to try to pull out useful bits of information. However, Oracle 11G had made that a lot easier. Step forward X$DBGALERTEXT. This is the decoded version of the XML version of the Alert log, and as such provides lots of lovely columns to filter by, rather than a single line of text to decode. Particularly useful (for me) is the MESSAGE_LEVEL. Is this line of text informational (16), or critical (1), or something in between? Of course, each “normal” line of text is still available in the MESSAGE_TEXT column.
SQL> desc x$dbgalertext; Name Type ------------------------------ -------------------------------------------------------- ADDR RAW(4) INDX NUMBER INST_ID NUMBER ORIGINATING_TIMESTAMP TIMESTAMP(3) WITH TIME ZONE NORMALIZED_TIMESTAMP TIMESTAMP(3) WITH TIME ZONE ORGANIZATION_ID VARCHAR2(64) COMPONENT_ID VARCHAR2(64) HOST_ID VARCHAR2(64) HOST_ADDRESS VARCHAR2(46) MESSAGE_TYPE NUMBER MESSAGE_LEVEL NUMBER MESSAGE_ID VARCHAR2(64) MESSAGE_GROUP VARCHAR2(64) CLIENT_ID VARCHAR2(64) MODULE_ID VARCHAR2(64) PROCESS_ID VARCHAR2(32) THREAD_ID VARCHAR2(64) USER_ID VARCHAR2(64) INSTANCE_ID VARCHAR2(64) DETAILED_LOCATION VARCHAR2(160) PROBLEM_KEY VARCHAR2(64) UPSTREAM_COMP_ID VARCHAR2(100) DOWNSTREAM_COMP_ID VARCHAR2(100) EXECUTION_CONTEXT_ID VARCHAR2(100) EXECUTION_CONTEXT_SEQUENCE NUMBER ERROR_INSTANCE_ID NUMBER ERROR_INSTANCE_SEQUENCE NUMBER VERSION NUMBER MESSAGE_TEXT VARCHAR2(2048) MESSAGE_ARGUMENTS VARCHAR2(128) SUPPLEMENTAL_ATTRIBUTES VARCHAR2(128) SUPPLEMENTAL_DETAILS VARCHAR2(128) PARTITION NUMBER RECORD_ID NUMBER
Very handy. Just add your own view, synonym and permissions to read the view, and you’re away…
create view v_$alert_log as select * from x$dbgalertext; create public synonym v$alert_log for sys.v_$alert_log; grant select on v$alert_log to whomever... 1* select message_text from v$alert_log where ...; MESSAGE_TEXT ----------------------------------------------------------------- LICENSE_MAX_SESSION = 0 LICENSE_SESSIONS_WARNING = 0 Shared memory segment for instance monitoring created Picked latch-free SCN scheme 2 Autotune of undo retention is turned on. LICENSE_MAX_USERS = 0 SYS auditing is disabled Starting up: Oracle Database 11g Enterprise Edition Release 18.104.22.168.0 - Production With the Partitioning, OLAP, Data Mining and Real Application Testing options. Using parameter settings in server-side pfile /home/oracle/app/oracle/product/11.2.0/dbhome_2/dbs/initorcl.ora System parameters with non-default values: processes = 200 sessions = 322 sga_max_size = 2G pre_page_sga = TRUE nls_language = "ENGLISH" nls_territory = "UNITED KINGDOM" filesystemio_options = "SetAll" sga_target = 2G control_files = "/u02/oradata/orcl/control01.ctl" . [snip] . aq_tm_processes = 1 diagnostic_dest = "/u20/apps/oracle" PMON started with pid=2, OS id=2492 PSP0 started with pid=3, OS id=2494 VKTM started with pid=4, OS id=2512 at elevated priority VKTM running at (1)millisec precision with DBRM quantum (100)ms GEN0 started with pid=5, OS id=2520 DIAG started with pid=6, OS id=2522 ...etc...