Storage for DBAs


This page contains an index to an extended blog series I have been writing called Storage for DBAs. As a long-time database guy entering the murky world of storage, I found three were a lot of lessons to learn and myths to debunk.

It’s not a great name for a blog series because it’s not just aimed at DBAs but also architects, developers, administrators of any kind, managers, buyers and anyone with an interested in modern storage. However, in these Twitter-friendly times, the name Storage For Architects, Developers, Administrators of Any Kind, Managers, Buyers and Anyone with an Interest in Modern Storage didn’t seem very catchy.



Storage Fundamentals:

Performance: It’s All About Balance

The Fundamental Characteristics of Storage

Understanding I/O: Random vs Sequential (The Sushi Effect!)

Does My Database Need Flash?

The Most Important Thing You Need To Know About Flash

Storage Myths:

Storage Myths: IOPS Matter

Storage Myths: Put Oracle Redo on SSD

Storage Myths: Dedupe for Databases

Storage Myths: Storage Compression Has No Downside

Playing The Data Reduction Lottery

Database Economics:

The Real Cost of Enterprise Database Software

The Real Cost of Oracle RAC

The Most Expensive CPUs You Own

Understanding Disk:

Understanding Disk: Superpowers

Understanding Disk: Mechanical Limitations

Understanding Disk: Over-Provisioning

Understanding Disk: Caching and Tiering

Understanding Flash:

Understanding Flash: What Is NAND Flash?

Understanding Flash: Blocks, Pages and Program / Erases

Understanding Flash: SLC, MLC and TLC

Understanding Flash: What is 3D NAND?

Understanding Flash: The Flash Translation Layer

Understanding Flash: Garbage Collection Matters

Understanding Flash: The Write Cliff

Understanding Flash: Unpredictable Write Performance

Understanding Flash: Floating Gates and Wear

Understanding Flash: Fabrication, Shrinkage and the Next Big Thing

Understanding Flash: Summary – NAND Flash Is A Royal Pain In The …

All Flash Arrays:

All Flash Arrays: What Is An AFA?

All Flash Arrays: Can’t I Just Stick Some SSDs In My Disk Array?

All Flash Arrays: Where’s My Capacity? Effective, Usable and Raw Explained

All Flash Arrays: SSD-based versus Ground-Up Design

All Flash Arrays: Hybrid Means Compromise

All Flash Arrays: Controllers Are The New Bottleneck

All Flash Arrays: Active/Active versus Active/Passive

All Flash Arrays: Scale Up vs Scale Out (Part 1)

All Flash Arrays: Scale Up vs Scale Out (Part 2)

Flash Debrief:

Flash Debrief: The End (Part 1)

The Final Post: Hardware Is Dead (Part 2)


12 Responses to Storage for DBAs

  1. Have opened this page many times but could never manage to read the posts. Finally started reading today.

    Great stuff.

    Thank you !

  2. Raviteja Chilakamarthi says:

    Amazing wealth of information.

  3. Pingback: SQL Performance, Part II — Disk I/O: metrics and scales | Oracle Diagnostician

  4. Aa ab says:

    Thanks for the articles. You explain an complicated topic with so much simplicity. I learned a lot.

  5. István says:

    Thank you so much for these articles, they helped me a lot. I just started to digging into data recovery.

  6. Jane Zhou says:

    The most understandable and best-written technology blog.

      • Jane Zhou says:

        I read through almost all the articles. These are very helpful! I will be a faithful reader continuously.

        One message you shared is the power consumption of SSD is lower than HDD. Theoretically yes. Do you have any data point to compare, and whether the interface of SAS, SATA, PCIe will have impact on the power consumption. The reason put forward this is from my experience, 2.5″ SAS HDD usually consumes 11W power, while the latest PCIe SSD power is budgeted at 25W.

        Any blog you want to recommend also helps.

        • flashdba says:

          Hi Jane

          The data sheets of SSDs and HDDs will show you a reasonable difference in power consumption, but that’s only half the story. Consider also the fact that many more HDDs are required to meet the same performance levels of a handful of SSDs, particularly for random I/O where IOPS becomes the limitation. Even the fastest HDDs can deliver not much more than 200 IOPS, while a single Samsung PM863 SSD can deliver almost 100,000.

          On the subject of comparing specifications, you must always ensure you are comparing like for like. SSDs come in consumer or enterprise-class categories and will have significantly different performance and environmental specifications. For HDDs this is even more the case, with so many combinations and permutations on sale. Be careful you don’t compare the power draw of a mid-range consumer HDD to a high-end SSD.

          Finally, I have no insights on the effect of the interface, but what is interesting about SSD power consumption (in my humble opinion) is that the type of NAND flash used (e.g. MLC versus TLC) has a significant effect, as of course does the fact that writes use more power than reads. You can see an interesting graphic displaying this exact phenomenon in this review of the class-leading Samsung PM863 and SM863 solid state drives, which are wildly popular in the enterprise flash array space:

  7. Bilal Inamdar says:

    Hi flashdba..
    Is there any tool to measure the io latency, iops, bandwidth to compare two storage system before migration ? I found so many but as you have a great deal of knowledge based on the point of view of oracle dba that i need to ask you before search all over the place.
    The tools i found are iostat,iometer,iozone,fio,vdbench,slob,swingbench,benchmarkfactory and many more. I would like to know how do you exactly test for the latency,bandwidth and iops when you do a benchmark. And what exact parameter you use and what you look for in the results.


  8. varad says:

    Very Much informative. Thanks Team

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