If you are talking about incredible speed and extreme scalability, then you are talking about Oracle Exadata, a unique blend of server, storage, OS, database technologies offering wide possibilities in the OLTP and Data warehouse sites.
Pakistani Telcos and Banks and even some of the industries are running very high-volume and high load databases which need to be up 24 by 7, demanding resilience in the face of ever-increasing load and require lightening fast performance.
At the first look, Exadata looks horrendously expensive, but for the visionary CIOs and DBAs, that is an investment for the lifetime, which allows them to phase out numerous servers and storages, and consolidate their IT investment.
Pakistani market is ripe for Exadata.
Monday, June 21, 2010
Sunday, June 20, 2010
Exadata DBA
Well I guess I am like thosuands of DBAs out there, who are intrigued, excited, curious, and yearning to lay their hands on Exadata, which looks sure enough the future of OLTP and DW for the large and even medium size enterprises across the globe.
What should a typical DBA who is aware of core database, RAC, Data Guard, ASM should do to learn about Exadata without having it?
Exadata is kind of "different Oracle", for example it doesn't require indexing on table that much and so and so. So the DBAs need to re-define themselves to manage the Exadata?
Yes, storage concepts and the hardware concepts do matter when it comes to manage the Exadata, but how much knowledge in this regard is expected from the DBAs?
What are the responsibilities of an Exadata DBA?
I believe that some of above questions overlap, but would appreciate any answers in that regard.
And I got following responses from the experts:
An exdata DBA need experience in Database, Storage and OS.
A good understanding of SmartScan and Hybrid Columnar Compression. (ctrieb)
If you can answer the question "Why with Exadata do I probably not need [some or all of my] indexes?" you are on the right road. (Dan Morgan)
Learn all you can about direct path reads as they are critical to enable smart scan. Serial direct path reads are done often in 11gR2, probably because of Exadata influence.
Learn about parallel query and the mechanisms available to throttle it (queuing is now available in 11gR2).
ASM provides the redundancy on the disks, so make sure you are familiar with the options provided.
Knowing something about Infiniband would probably be a good idea as well since you'll have to figure out how to connect to external devices (tape drives for example).
Read all the Oracle published white papers (there are quite a few out there now).
There are a few blogs with some info: Kevin Closson has several posts on his blog (although he's kind of fallen off the Exadata wagon lately - but we all have real jobs), I have posted a few as well. There will be more information coming available as more people get access to them. Oracle seems to be selling them like hotcakes.
Throwing all the indexes out will probably not be the right approach for most mixed workloads, by the way. Although migrating to Exadata may provide an opportunity to get rid of a bunch of unneeded indexes. A lot of systems have a bunch of indexes that aren't needed to begin with. (Kerry Osborne)
What should a typical DBA who is aware of core database, RAC, Data Guard, ASM should do to learn about Exadata without having it?
Exadata is kind of "different Oracle", for example it doesn't require indexing on table that much and so and so. So the DBAs need to re-define themselves to manage the Exadata?
Yes, storage concepts and the hardware concepts do matter when it comes to manage the Exadata, but how much knowledge in this regard is expected from the DBAs?
What are the responsibilities of an Exadata DBA?
I believe that some of above questions overlap, but would appreciate any answers in that regard.
And I got following responses from the experts:
An exdata DBA need experience in Database, Storage and OS.
A good understanding of SmartScan and Hybrid Columnar Compression. (ctrieb)
If you can answer the question "Why with Exadata do I probably not need [some or all of my] indexes?" you are on the right road. (Dan Morgan)
Learn all you can about direct path reads as they are critical to enable smart scan. Serial direct path reads are done often in 11gR2, probably because of Exadata influence.
Learn about parallel query and the mechanisms available to throttle it (queuing is now available in 11gR2).
ASM provides the redundancy on the disks, so make sure you are familiar with the options provided.
Knowing something about Infiniband would probably be a good idea as well since you'll have to figure out how to connect to external devices (tape drives for example).
Read all the Oracle published white papers (there are quite a few out there now).
There are a few blogs with some info: Kevin Closson has several posts on his blog (although he's kind of fallen off the Exadata wagon lately - but we all have real jobs), I have posted a few as well. There will be more information coming available as more people get access to them. Oracle seems to be selling them like hotcakes.
Throwing all the indexes out will probably not be the right approach for most mixed workloads, by the way. Although migrating to Exadata may provide an opportunity to get rid of a bunch of unneeded indexes. A lot of systems have a bunch of indexes that aren't needed to begin with. (Kerry Osborne)
Tuesday, June 1, 2010
ORA-00470: LGWR process terminated with error in 11g on Windows
In one of my test servers, I am using Oracle 11.1.6 on Windows Server 2008. The services of listener and database are automatic. Normally when I boot the machine, the listener starts, and as the database starts, the PMON automatically registers the database with the listener.
This morning when I booted the machine, both services were up, listener was also up,but the database was in mount state, and when I did:
SQL> conn sys as syssdba
SQL> alter database open;
it gave following error:
ORA-00470: LGWR process terminated with error
I resolved the error by doing following steps, when the database was at mount state:
SQL> recover database until cancel;
SQL> alter database open resetlogs;
Now the database was opened fine. The problem seems to be caused by an I/O error
reading/writing to
the redo log that causes Oracle to not be able to startup with the current state of the redo thread.
This morning when I booted the machine, both services were up, listener was also up,but the database was in mount state, and when I did:
SQL> conn sys as syssdba
SQL> alter database open;
it gave following error:
ORA-00470: LGWR process terminated with error
I resolved the error by doing following steps, when the database was at mount state:
SQL> recover database until cancel;
SQL> alter database open resetlogs;
Now the database was opened fine. The problem seems to be caused by an I/O error
reading/writing to
the redo log that causes Oracle to not be able to startup with the current state of the redo thread.
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