Availability and Capacity Management

 

For people familiar with ITIL, the above two words should not be alien. I was introduced to ITIL in 2006 as ITIL implementation was sort of my primary job for the first 1.5 years of my professional life. IT Infrastructure Library (ITIL) is a set of best practices that organizations should implement for IT Services Management. However, when I was attending a three day workshop on ITIL v3, I realized the basic principles of ITIL can be applied to manage anything and not just IT Services.

Two of the processes are Availability management and Capacity Management.What do they mean? Suppose you have been made in-charge of water supply at a 3 day NCC camp for 450 cadets. The first question is how much water are you going to need per day. Lets say you need 1500 liters of water per day. Fine. But  you need to store this water. You have been provided with 2 storage tanks of 500 liters. This is your capacity, ie 1000 liters. But you notice that your capacity is less than the daily requirement. What should you do about it? You ask for another tank, but your commanding officer informs you that a pump powered by a genset will fill the tanks when the need arises. So even though you do not have full capacity to serve the daily need, you can still ensure availability thanks to the genset powered pump. Of course, you will have to ensure that the diesel for the genset is available when required. By finely balancing the capacity and availability, you are able to meet the demand and a lot of satisfied cadets. Also notice that having the tanks (capacity) does not ensure availability.

This is a very simple scenario, but something which we find almost everywhere. Do your servers have the capacity to process 100,000 simultaneous requests? Do you have sufficient developers to finish a particular project in 2 months time (Capacity)? Are all the developers available during this time? I heard a couple of them are going on a trip to Ladakh (unavailable).  You get the basic idea, right!

Anil Enthu Kumar and I made an interesting observation a few weeks back. There is tea shop near his house which we frequent. Opposite to this tea shop is another tea shop, which pretty much provides the same services. However, the tea shop which we visit is more crowded and has more customers. Always! Lets call this the Tea Shop A and the one opposite, the less popular one as Tea shop B.  Both of us asked the same question, Why did we go to this particular tea shop A when we could have easily gone to the other one? The answer to that was, one amongst our group of friends had visited the Tea Shop A and the next time he went with the others, he chose that particular tea shop. So the others started going to the same tea shop. We never considered going to tea shop B. Why? Because Tea Shop A was available whenever we went. Tea shop B wasn’t always open, something which I noticed in the past few weeks. Availability giving the competitive edge to a tea shop, ensuring more customers!

Why the sudden post on availability and capacity management? Well I was trying to book a domain for the new project I am working on, but the site of ZNET India gave an error. It wasn’t available when I wanted it to be. While I am not going to any of their competitors (just yet), the fact is simple things like availability are such a critical part of the customer experience. Look at flipkart. It is one of the hottest startups in India today, and how did they reach here – by simply focusing on ensuring good service availability to their customers.

To end this random post, I think about the pressing problems we face – depleting water table, clean energy etc. Can we ensure availability of water? What happens if there is drought for two consecutive years and the monsoon fails as well? Do we have capacity to sustain the water needs of the ever growing populace? Can simple principles from capacity and availability management be applied to solve such problems? What do you think?

What is wrong with Google?

The header certainly got your attention, didn't it? What can be wrong with Google? Almost for a decade now Google has been there for us, searching the internet and finding us what we want. Apart from search, Google has brought us services which are part of our daily lives now, services like Gmail, Orkut, YouTube, Blogger and Google News. I use most of these services and as I said earlier you would hardly ever get any disruptions in these services. So reliable is the Google brand that one of my friends said they dont need any error pages. Except Orkut of course, where we abuse the Orkut server for refusing us donuts!!

But in the past two weeks I feel things are starting to come apart. Firstly, with Google News there have been almost five instances when the service failed its service levels. These were disruptions that I myself experienced being an avid Google News visitor. Then the Gmail spam filter, has started detecting genuine mails as spam. The ironical thing was the mails sent to spam were from ZDnet and I have a filter in place to divert them from the inbox to archive folders under the label ZDnet. But i found my spam folder filled with six such messages today!!

Of course these are just minor errors, but given my nature to speculate and the fact that such disruptions and mistakes have happened in a very short span of time, I thought I write about it.

Changing CSS having no effect!

In the week just gone by, I received a web app from one of my colleagues who was on medical leave. This was supposed to be a prototype of what I will be developing in the days to come. However, there were many issues with the UI of the site. The color scheme though looked good did not match with the logo of the company and had to be changed.

It took me some time to realize that the CSS file being used was one within the App_Themes folder and not the one outside. I had been making changes to the wrong file, hence the changes I was making were not reflecting. But hang on!! Now I was making changes to the correct file but still I could not see the changes reflecting in the front end. I double checked and was stumped. Just moments ago the changes made to the CSS were reflecting in the UI. What could be the possible reason now?

Somehow I had the feeling that I should refresh the page once(probably because of my experience with Service Desk Customization) and Bingo!!

Now I again I made some changes mainly changing the logo, but again it wasn't reflecting. I refreshed. Nothing!! Now what could be the reason? Thankfully I had a backup of the original CSS file. I compared that with the modified one. I realized what was happening. To work faster I was using the build style option in Visual Web Developer. When you use this a Window opens where you can visually set the CSS properties. I was using this to set the background image to the one I had created. The location of this image was "App_Themes/Theme1/Images/Image1.gif". So what was happening was the in the CSS the same url for the image was getting stored. But as my CSS file was already located at "App_Themes/Theme1/" the correct url for the image should have been "/Images/Image1.gif". I changed the Url and Voila!!

As I had posted earlier, Microsoft is always trying to simplify things by allowing you to code Visually. But this Visual coding style has pitfalls and is a sure source of many bugs in applications. My advice to all is "Be Extra Careful when writing code Visually!"

Cheers!!