New section: Oracle SLOB Testing

slob ghost

For some time now I have preferred Oracle SLOB as my tool for generating I/O workloads using Oracle databases. I’ve previously blogged some information on how to use SLOB for PIO testing, as well as shared some scripts for running tests and extracting results. I’ve now added a whole new landing page for SLOB and a complete guide to running sustained throughput testing.

Why would you want to run sustained throughput tests? Well, one (more...)

Understanding Flash: SLC, MLC and TLC

slc-mlc-tlc-fruitmachine

The last post in this series discussed the layout of NAND flash memory chips and the way in which cells can be read and written (programmed) at the page level but have to be erased at the (larger) block level. I finished by mentioning that erase operations take substantially longer than read or program operations… but just how big is the difference?

Knowing the answer to this involves first understanding the different types of flash (more...)

Understanding Flash: Blocks, Pages and Program / Erases

In the last post on this subject I described the invention of NAND flash and the way in which erase operations affect larger areas than write operations. Let’s have a look at this in more detail and see what actually happens. First of all, we need to know our way around the different entities on a flash chip: the die, the plane, the block and the page:

NAND Flash Die Layout (image courtesy of AnandTech)

NAND Flash Die Layout (image courtesy (more...)

New My Oracle Support note on Advanced Format (4k) storage

advanced-format-logo

In the past I have been a little critical of Oracle’s support notes and documentation regarding the use of Advanced Format 4k storage devices. I must now take that back, as my new friends in Oracle ASM Development and Product Management very kindly offered to let me write a new support note, which they have just published on My Oracle Support. It’s only supposed to be high level, but it does confirm that the _DISK_SECTOR_SIZE_OVERRIDE (more...)

Understanding Flash: What Is NAND Flash?

circuit-board

In the early 1980s, before we ever had such wondrous things as cell phones, tablets or digital cameras, a scientist named Dr Fujio Masuoka was working for Toshiba in Japan on the limitations of EPROM and EEPROM chips. An EPROM (Erasable Programmable Read Only Memory) is a type of memory chip that, unlike RAM for example, does not lose its data when the power supply is lost – in the technical jargon it is non-volatile. It does (more...)

Understanding Disk: Caching and Tiering

 

roulette-and-casino

When I was a child, about four or five years old, my dad told me a joke. It wasn’t a very funny joke, but it stuck in my mind because of what happened next. The joke went like this:

Dad: “What’s big at the bottom, small at the top and has ears?”

Me: “I don’t know?”

Dad: “A mountain!”

Me: “Er…<puzzled>…  What about the ears?”

Dad: (Triumphantly) “Haven’t you heard (more...)

Oracle SLOB On Solaris

Guest Post

This is another guest post from my buddy Nate Fuzi, who performs the same role as me for Violin but is based in the US instead of EMEA. Nate believes that all English people live in the Dickensian London of the 19th century and speak in Cockney rhyming slang. I hate to disappoint, so have a butcher’s below and feast your mince pies on his attempts to make SLOB work on Solaris without (more...)

How To Succeed In Presales?

success-and-failure

This article is aimed at anyone considering making the move into technical presales who currently works in a professional services, consultancy or support role, or as customers and end-users. You will notice that the title of the article has a question mark at the end – that’s because I don’t have the answer – and I have neither the confidence nor the evidence to claim that I have been a success. But I have made lots (more...)

The Ultimate Guide To Oracle with Advanced Format 4k

fud

It’s a brave thing, calling something the “Ultimate Guide To …” as it can leave you open to criticism that it’s anything but. However, this topic – of how Oracle runs on Advanced Format storage systems and which choices have which consequences – is one I’ve been learning for two years now, so this really is everything I know. And from my desperate searching of the internet, plus discussions with people who are usually much knowledgeable than (more...)

A New Approach To My Blogroll

Like most people, I have a panel on the right hand side of my blog which contains my blogroll, i.e. a list of links to the blogs of other people I respect and admire. And like most people in the Oracle world, up until today it was full of the same names you always see. To pick three examples:

Tanel Poder – One of the most interesting and entertaining Oracle experts around, someone you (more...)