Storage Myths: IOPS Matter

Storage for DBAs: Having now spent over a year in the storage industry, I've decided it's time to call out an industry-wide obsession that I previously wasn't aware of: everyone in storage is obsessed with IOPS (the performance metric I/O Operations Per Second). Take a minute to perform a web search for "flash iops" and … Continue reading Storage Myths: IOPS Matter →

The Role Of The DBA

I'm back at work today after a week's travelling around Europe followed by a week's holiday sailing around the Ionian Sea. I have to say that I'd rather still be on holiday. It's not that I don't enjoy my job (I love it) but... Today, I need to install some database software - and it … Continue reading The Role Of The DBA →

SLOB2: Testing The Effect Of Oracle Blocksize

I recently posted a test harness for generating physical I/O using the new version of SLOB (the Silly Little Oracle Benchmark) known as SLOBv2. This test harness can be used for driving varying workloads and then processing the results for use in ... well, wherever really. Some friends of mine are getting very adept with … Continue reading SLOB2: Testing The Effect Of Oracle Blocksize →

New SLOB2 Physical I/O Harness

Short post to point out that I've now posted the updated PIO Test Harness for SLOB2. This can be used to run multiple SLOB tests with varying numbers of workers and values of UPDATE_PCT. In addition there is also a revised version of the AWR analyzer shell script which can be used to extract various … Continue reading New SLOB2 Physical I/O Harness →

SLOB: PL/SQL Commit Optimization

I ran some SLOB tests over the weekend using the new SLOBv2 kit and noticed some interesting results. I was using SLOB to generate physical I/O but the "anomaly" is best demonstrated by putting SLOB in "Logical I/O mode", i.e. by having a large enough buffer cache to satisfy all reads. I'm calling SLOB with the … Continue reading SLOB: PL/SQL Commit Optimization →

SLOB2: Essential for Every DBA Toolkit

A couple of weeks ago, Kevin released the second version of SLOB - the Silly Little Oracle Benchmark. Readers will know that I was already a big fan of the original version, but version 2 (which I was fortunate enough to test prior to its release) now has extra features and functionality which make it … Continue reading SLOB2: Essential for Every DBA Toolkit →

The Most Important Thing You Need To Know About Flash

Storage for DBAs: There are many things you need to know about flash: it's performance, it's behaviour, it's durability etc. But there's one single piece of information which tells you more than anything else, because it gives you an insight into the future of not just flash memory, but the primary data storage industry. Let … Continue reading The Most Important Thing You Need To Know About Flash →

Does My Database Need Flash?

Storage for DBAs: Here's a question I get asked a lot: "Does my database need flash?". In fact it's the most common question customers have, followed by the alternative version, "Does my database need SSD?". In fact, often customers already have some SSDs in their disk arrays but still see poor performance, so really I … Continue reading Does My Database Need Flash? →

Understanding I/O: Random vs Sequential

Storage for DBAs: Ever been to one of those sushi restaurants where the food comes round in dishes on a conveyor belt? As each dish travels around the loop you eye it up and, as long as you can make your mind up in time, grab it. However, if you are as indecisive as me, there's a … Continue reading Understanding I/O: Random vs Sequential →

Strange ASM Behaviour with 4k Devices

This is only a short post to document something I've seen and reproduced but still don't understand. Storage devices generally have a physical sector size of 512 bytes or, more recently, 4k. This is a subject which causes much confusion (partly because some vendors seek to portray whichever sector size they use as "better"). You … Continue reading Strange ASM Behaviour with 4k Devices →