Tag Archives: sharing

Queue-depth

Config Guide General Info Troubleshooting No Comments

I recently was involved in a discussion around QD settings and vendor comparisons. It almost got to a point where the QD capabilities were inherently linked to the quality and capabilities of the arrays. Total and absolute nonsense of course. Let me make one thing clear “QUEUING IS BAD“. In the general sense that is. Nobody want to wait in line nor does an application.

Whenever an application is requesting data or is writing results of a certain process it will go down the I/O-stack. In the storage world there are multiple locations where such a data portion can get queued.When looking at the specifics from a host level the queue-depth is set on two levels.

(p.s. I use the terms device, port, array interchangeably but they all refer to the device receiving commands from hosts.)

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Speed mismatch is the death-trap for shared storage

Config Guide Fibre Channel Storage Networking Troubleshooting 2 Comments

I’ve been focusing on the implications of physical issues a lot in my posts over the last ~2 years. What I haven’t touched on is logical performance boundaries which also cause extreme grief in many storage infrastructures which lead to performance problems, IO errors, data-corruption  and other nasty stuff you do not want to see in your storage network.

Speedometer

 

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RTFM

Storage Networking No Comments

Yeah its been a while. A lot has happened in two years. One thing that really jumps out is I moved Down Under. Yep, now inhabitant of kangarooland and I’ve loved every day of it.

To storage:
You don’t want to know how many questions I get who’s answers have been perfectly described in all sorts of manuals. This almost leads to the point were my job becomes a manual reader and a walking storage encyclopedia. 🙂 Now that’s something to put on my CV.


The big problem is however with so many different (storage) products and related documentation I can understand the problem storage admins have these days. Storage infrastructures become more and more complex and an ever increasing level of knowledge is required to maintain all of this. Take into account all different updates these guys get from their vendors almost on a monthly basis then you can imagine what their workday looks like. My life is pretty easy. I only have to keep track of around 80 software products and approx 15 storage hardware platforms because I work for one of those vendors. Multiply that by an average of around 17 manuals per product between 10 and over 5000 (yes, five-thousand) pages and …… you do the maths. Take into account that I also need to know what happens on a OS level from an IO stack perspective including all the different virtualisation kit that is out there including Mainframe z/OS so this pretty much sums up my daily life.. 😉

No, I’m not pitying myself. I have a fantastic wife, wonderful kids and good job, so I’m quite happy with what’s going on in my life.

Going back to the storage admins. The big difference between them and myself is I have access to all the information I need plus some competitive information of my com-colleagues. The storage admins totally rely of what the vendors want them to have and that very often is extremely restricted. I can understand that a lot of this is market sensitive and belongs as company confidential behind locks, however I also think that we should give the right information/documentation (in any form you like) in a structured and easy to understand format without the nitty/gritty stuff that is totally irrelevant. This will easy the burden which a lot of you guys out there suffer and believe me I’ve been there.

A second way of sharing experiences and knowledge is user communities. The perfect example for me has always been Encompass or DECUS. The best user community ever, affiliated to Digital Equipment Corporation. (HP still picks the fruit from that). I think it’s extremely important that vendor should provide a platform were their users can share expierences (good or bad) and be able to leverage the knowledge of his/her peers.

One of my primary tasks, besides being a technical conscience to my sales reps, is to provide my customers (you storage admins) with all the information they need and to help them manage the kit I sold them so they can be heroes within their company.

TTY later.

Greetz,
Erwin