Capacity planning is a huge headache for the IT professional, no matter the scale: Too much capacity, and you’re wasting money and resources, but too little and you’re risking a shortage.  Prospective Microsoft Windows Azure cloud customers in the South Central US data center region are discovering they are on the wrong side of that equation, finding themselves without the ability to purchase compute or storage resources (Current customers are unaffected). Word comes in the form of an official Microsoft Windows Azure blog entry, which explains that the team is both “excited” and “humbled” by Azure’s adoption rates. All the same, while Microsoft is expanding the platform’s capacity as quickly as it can, there are limits to what its current infrastructure can handle, and it’s hit a threshold in some regions where in order to help current customers scale, existing customers have to be left in the cold. As of today, new customers in the South Central US Azure region won’t be able to purchase compute or storage resources – though Service Bus, Caching, Access Control and SQL Azure remain available. Existing customers deployed in that region aren’t affected by this news. On the flip side, Windows Azure recently launched two new regions, East US and West US, the former of which also just added SQL Azure cloud databases to its services lineup. The lesson here is that there’s such a thing as too much popularity. Remember, to the CIO, employees are the customers when it comes to the cloud. It’s impossible to get your capacity demands exactly right, but when you miss the mark and have to scale down for capacity, you’re not exactly delighting anybody. At the same time, though, shutting down signups is almost definitely better than scaling out of control and causing another outage.