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Scripting

Remove Files with Force and Other Bad Ideas

Almost every Linux or Unix person has seen the help forum post from a novice looking for an answer to a frustrating problem and the arrogant fool that responds with “Just type in rm -rf / and it will fix the problem.” For anyone who is part of the “do no harm” technical community, this can make us wish for a way to revoke the arrogant fool’s privileges to the internet— permanently.

IOsaturationtoolkit-v2 with Exadata IORM and AWESOME text graph

I’ve got a new version of IOsaturation toolkit which you can download here https://karlarao.wordpress.com/scripts-resources/ and it has a cool script called “smartscanloop” that shows you the Smart Scan MB/s per database across the Exadata  compute nodes.. it’s a per 2secs sample so that’s a pretty fine grained perf data and near real time text graph. Very useful for doing IORM demos and monitoring what database is currently hogging the IO resources and since it’s presented in a consolidated view you don’t have to go to each Enterprise Manager performance page and have a bunch of browser windows open.

Knowing the trend of Deadlock occurrences from the Alert Log

Recently, my client deployed a new application and had this intermittent “Deadlock Storm” …

A trace file was sent and I was able to pinpoint the cause of the deadlock and the session that caused it.
The deadlock was a TX enqueue with mode of 4 (S – share) which could be verified by looking at the following lines of the Process State dump:

   last wait for 'enq: TX - row lock contention' blocking sess=0x 7000000cb239d60 seq=7849 wait_time=2929705 seconds since wait started=3
            name|mode=54580004, usn<<16 | slot=a0028, sequence=283f2

the "enqueue and lock mode" is explained as:
mode=54580004 (see above)
5458 (hex) = TX (ascii)
0004 (hex) = mode 4 (S – share)