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A 100TB Database June 23, 2009

Posted by mwidlake in development, VLDB.
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Some of you may know of me as the guy who constantly presented on the “massive database of genetic information” he was creating. I started presenting about it around 2003 and I said it would be 7TB. As I built it, the data kept flooding in and by the time I had it up and running and fully populated, around 2005, it was getting scary – it had grown to over 25TB. Who am I kidding? It was beyond scary, it kept me awake at nights.

Well, it still exists and continues to grow. I saw it up to 45TB before I left the Sanger institute {where I built it} and it continues to grow towards the 100TB I designed it to scale to.

Why am I bragging about this? {” hey, have you seen the size of my database”?!}. Well, I am very proud of it. It was my pet project.

But pet project or not, I had a team of DBAs at the Sanger and of course, when I say “I built it” I should say “My team and I built it”. And they looked after it after I departed and it got even bigger.

Last week I got an email off one of them to invite me over for a small celebration this week. What are we celebrating? The first database on-site to hit 100TB. Am I proud? Hell yes, I am proud.

But not proud of what you probably think I am, given my careful preamble.

It is not my database that has broached the 100TB limit.

It is another one, a database the team put together after I left and that they have looked after without my input. What I am really proud about is that, with Shanthi Sivadasan who was holding the fort when I arrived at the Sanger {and remains there}, we put together a team of DBAs that is capable of creating and looking after such a large behemoth. It could not be done without excellent support from the Systems Administrators as well, but I feel particularly proud of the DBAs.

So congratulations to the DBAs at the Wellcome Trust Sanger Institue: Shanthi Sivadasan, Tony Webb, Andy Bryant, Aftab Ahmed, Kalyan Kallepally and Karen Ambrose. You went further with this than I did.

I hope that the cake to celebrate is very nice :-)

The Knowledge Curtain. June 8, 2009

Posted by mwidlake in development, Management, Perceptions.
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I came across the concept of “The Knowledge Curtain” in the late 90’s, from a man called Lee Young, who I worked with for 2 or 3 years, along with a friend Mike Cox, who was key to showing me how to peek through the curtain.

The below is taken from a powerpoint presentation I sometimes give on project disasters (how to avoid, not how to encounter!):

When systems designers talk to end users, both parties usually end up not really understanding each other

When systems designers talk to end users, both parties usually end up not really understanding each other

The basic principle is that, the knowledge of your users/customers is partly hidden from you. When you ask people for whom you are designing a computer system about their job, they don’t tell you lots of stuff.

  • Things that they assume you know.
  • Things that it does not occur to them to mention.
  • Things that they do not want to admit to doing as it sounds silly or badly managed.
  • I’ve even had people not mention parts of their job as they don’t want their manager knowing they do it.

But that is OK, when you talk about information technology and computer systems to them, they have exactly the same problems with what you say :-).

Lee’s presentation, with N. Mehandjiev, predated the all-encompasing rise of the internet and this is one of the few references to it I can find. {Among the relatively few other hits on the topic, amongst the ones about knowing how to make curtains, are references to the “Knowledge Curtain” as the concept that the Web is not as available in other areas of the world. A related but very different issue}.

So, how do you peak beyond the knowledge curtain? Systems designers and developers with experience learn how to ask the questions “what are the exceptions to what  you have just told me” and “what else do you do” in many, many ways and without giving offence. After all, you have to keep asking these two questions and people naturally get irritated with that and some feel you are suggesting they are either stupid or lying. It can be tricky. 

I think that unless you have someone who is fully IT literate and has done the job the computer system is to assist with, you will inevitably only catch a part of the requirements.

For massive projects over many months or years, I think this lack of a clear understanding of what people do is a major factor to their failures. This is made even worse when the analysis is done by one group of people and the specifications are then shipped out to an external party for the application to be developed. With all that missing knowledge, it is no wonder some systems are initially so poor.

I only know of one method that reliably allows you really see beyond the knowledge curtain. That is prototyping and user feedback. Only when you show the people who are going to use the system what you have put together to help them will they know if it works. These sessions are incredibly valuable and only in development projects where they have been key to process have I seen the project deliver something truely useful.

I now have a general way of developing anything.

  • I ask the users for 3 or 4 major things that they want the system to do.
  • I develop those 3 or 4 features as quickly as possible and show them to the users.
    • One will be almost exactly what they need.
    • One or two will be close to what they need.
    • One will be utterly useless.
    • During the above, one or two critical new needs will come up.
  • Fix the close ones, dump or redo the useless one and add the new needs to the list.

Simply cycle around the above, asking for new features when you have got less than 4 features you  are actively working on. And only polish features (add all the nice screen touches and widgets) once is is exactly what they need or pretty damned close. {You hardly ever run out of features before you run out of time and money!} You end up with an excellent system that evolves to better help the customer as time goes on.

There are lots of development methodologies that have the above principle (or a variation of it) as their core, so I am certainly not the first person to find that this method works. Which is why I find it difficult to understand why so many projects don’t use it?

BTW, I thought I would just add that one of the factors in my starting a blog was a comment by Andrew Clarke on his, several years ago before Blogging really took off. It was for a presentation I did which included the Knoweldge Curtain concept. He was very nice about my presentation and I still appreciate it. This is the link, but as it is an archive you will have to search for my name.


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