Re: Big systems IT disasters?
ERP systems try to provide catch-all provision to a lot of individual requirements. As RDBMS products they depend on a database schema that probably started off trying to capture a "typical" business with various add-ons to pick up variations.
For instance the core might be something that sells finished items such as a garment business. It might have to deal with quantity discounts but it's simple. Stock control is just how many of this, that & the other. A business that sells the fabric from which the garments are made may, provided it just sells whole rolls of fabric may have the same simple model but one that cuts and sells lengths of fabric has somewhat different requirements as there may be a number of rolls of the same material, all with different lengths and there may be a need for algorithms to determine the bast way to choose which of them to pick to fill an order to minimise being left with short ends. The factory which makes the garments has to deal with both types of items as it needs to account for raw materials and stock.
Other customers might have more complex requirements such as complex bills of materials - a kit comprising several parts might be charged at a different price than the sum of the various parts sold separately. Another requirement might be a need to account for serial-numbered parts. In the early days of the mobile phone industry both were combined in that the product might be a receiver, a car kit and a variety of other bits and pieces giving the bill of material problems together with the need to keep track of the serial numbers.
Some businesses have quite different approaches - I had a client who had a conventional ERP which was based on stock control and order processing which dealt with stationery logistics and a separate system to deal with print ordering because the print business looks at things in a quite different way and there are specific products for that.
So an ERP system which provides for the various application fields grows to be a complex beast. That's just the start, however. Businesses will have their own ways of doing things which, rightly or wrongly, they think gives them a competitive edge. If they find themselves using the same vanilla package as their competitors they'll have to give up their quirks, in which case they have the costs of adapting their processes and lose their supposed edge, or have the package modified to suit. Again, the client I mentioned had to get custom additions to their general ERP because they needed to acquire data to be passed on to a digital print operation to produce custom printed product (I was lucky in this, the printers were also one of my clients so I could handle both sides of interface between the businesses).
It's this last part that's the killer. If the changes needed to the business to fit the package or the changes needed to the package to fit the business are too great then failure beckons.