In recent articles in this series I’ve been looking at the architectural choices for building All Flash Arrays (AFAs). I surmised that there are three main approaches:
- Hybrid Flash Arrays
- SSD-based All Flash Arrays
- Ground-Up All Flash Arrays (which from here on I’ll refer to as Custom Flash Module arrays or CFM arrays)
I’ve already blown metaphorical raspberries at the hybrid approach, so now it’s time to cover the other two.
What’s the most important attribute to consider when you want to buy a new storage system? More critical than performance, more interesting than power and cooling requirements, maybe even more important than price? Whether it’s an enterprise-class All Flash Array, a new drive for your laptop or just a USB flash key, the first question on anybody’s mind is usually: how big is it?
Yet surprisingly, at least when it comes to All Flash Arrays, (more...)
There’s a joke among some of the longer-serving employees of Violin Memory that “Violin years” are like dog years: every normal year feels like a decade. It’s not meant in a negative way, it’s just that things change so quickly and dramatically in the flash industry that whenever we take a moment to look back it seems impossible to believe that it was only a few years ago when flash was considered a new technology and we were (more...)
In the previous post of this series I outlined three basic categories of All Flash Array (AFA): the hybrid AFA, the SSD-based AFA and the ground-up AFA. This post addresses the first one and is therefore aimed at answering one of the questions I hear most often: why can’t I just stick a bunch of SSDs in my existing disk array?
Data Centre Dinosaurs
Disk arrays – and in this case we are mainly talking about (more...)
Almost exactly a year ago I published a post covering my first impressions of the ASM Filter Driver (ASMFD) released in Oracle 188.8.131.52, followed swiftly by a second post showing that it didn’t work with 4k native devices.
When I wrote that first post I was about to start my summer holidays, so I’m afraid to admit that I was a little sloppy and made some false assumptions toward the end – assumptions (more...)
For the last couple of years I’ve been writing a series of blog posts introducing the concepts of flash-memory and solid state storage to those who aren’t part of the storage industry. I’ve covered storage fundamentals, some of what I consider to be the enduring myths of storage, a section of unashamed disk-bashing and then a lengthy set of articles about NAND flash itself.
Now it’s time to talk about all flash arrays. (more...)
In a proud moment for me, it appears that Mark Hurd, CEO of Oracle, has mentioned my flashdba blog during the Oracle Q4 2015 results call. At least, that’s what I’m reading into this section from the transcript published by Seeking Alpha:
We grew in storage in the quarter and this is — really we are going through a shift in storage now. We released our SAN product FS1 in the quarter which (more...)
So this is it – the last article in my mini-series on understanding flash. This is the bit where I draw it all together in a neat conclusion that makes you think, “Yes! That was worth reading”. No pressure eh?
So let me start with the conclusion first: as a storage medium, NAND flash is a royal pain in the ass.
Why? Well, let’s look back at what we’ve learned in the previous 9 (more...)
This is a very simple post to show the results of some recent testing that Tom and I ran using Oracle SLOB on Violin to determine the impact of using virtualization. But before we get to that, I am duty bound to write a paragraph of text featuring lots of long sentences peppered with industry buzz words. Forgive me, it’s just the way I’m wired.
It is increasingly common these days to find database environments running (more...)
I’ve run into a few customers recently who have had problems with their ASM rebalance operations running too slowly. Surprisingly, there were some simple concepts being overlooked – and once these were understood, the rebalance times were dramatically improved. For that reason, I’m documenting the solutions here… I hope that somebody, somewhere benefits…
1. Don’t Overbalance
Every time you run an ALTER DISKGROUP <NAME> REBALANCE operation you initiate a large amount of I/O workload as (more...)