Blog Aggregator - Amardeep Sidhu

I’m a big fan of the Oracle documentation, but sometimes things go astray. A recent question by Aman Sharm about SQL sharing critera highlighted this…
In the 8iR3 manual, the decision process for finding matching SQL is listed as:

The text string of an issued statement is hashed. If the hash value is the same as a […]

WARNING: SCSI: 5519: Failing I/O due to too many reservation conflicts

I experience this issue on development environment where i am running 40 VM’s just using one bigger LUN ( 1 TB).

It’s not a good practice to run >20 VM’s , specially if VM is running MS-SQL servers.MS SQL are I/O intensive.However if you are using Q logic HBA’s you can change maximum queue depth to stop these Warning messages on VMware ESX server :

To set maximum queue depth for a QLogic HBA

1 Log in to the service console as root.

2 Verify which QLogic HBA module is currently loaded:

vmkload_mod -l | grep qla2300

Depending on the model of the HBA, the module can be one of the following:

qla2300_707 (ESX Server 3.0.x)

qla2300_707_vmw (ESX Server 3.5)

3 Run the following commands.

The example shows the

qla2300_707 module. Use the appropriate module based

on the outcome of

Step 2.

a esxcfg-module -s ql2xmaxqdepth=64 qla2300_707

b esxcfg-boot –b

In this case, the HBA represented by

ql2x will have its LUN queue depth set to 64.

4 Reboot.

I’ve been doing a lot of traveling recently, which as usual means that I’ve been doing a lot of reading. I normally take a novel with me when I’m on the road but based on some recommendations, I’ve been working through a batch of books on business analytics. First off was “Competing on Analytics”, the […]

Here’s an interesting point that’s just been raised on from the Oracle-L list-server:
Metalink bug: 5483301.8
If a column has a frequency histogram and a query uses an equality predicate over the column looking for a value that does not exists in the histogram then the CBO was estimating a cardinality of 1. This could favor Nested […]

Or, When MySQL Lies!
When I do a show slave status\G, sometimes mysqld will lie to me and give me a wrong Exec_Master_Log_Pos. Let me explain with a situation from last night.
This is the output of show slave status\G from mysql version 5.0.41-community-log:

mysql> show slave status \G
*************************** 1. row ***************************
[…]