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
Category: Blog
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
NAND flash development is driven by the consumer market – not the enterprise. The question to ask any flash vendor isn't "how fast?" but "where's your innovation?"
Does My Database Need Flash?
Not every database benefits from flash storage – knowing when it matters requires understanding how much I/O your workload generates, how random it is and how much latency is already costing you.
Understanding I/O: Random vs Sequential
Disk I/O forces a choice between random and sequential access – and that choice defines whether latency compounds or disappears. Flash makes the distinction irrelevant.
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
The Fundamental Characteristics of Storage
Latency, IOPS and bandwidth are the three properties that define any storage system – understanding how they relate to each other is the first step to knowing what your database actually needs.
Performance: It’s All About Balance…
Database performance problems are rarely solved by faster CPUs alone – the real issue is imbalance between resources, and disk latency is the silent bottleneck that flash storage changes.
New Blog Series: Storage For DBAs
DBAs and storage people speak different languages – this series bridges the divide, translating storage concepts into terms that make sense from a database perspective.
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