e.g. an arbitrary company having office in different location like USA, UK & Singapore. At present all employees are in single AD. All SharePoint applications are in a single Farm. What should be driving force (and when) you should decide to go for multiple farms for this SharePoint 2010 applications. What all factors will drive you to do that? Hope I am able to explain my question correctly.
We recently broke apart our US farm because of speed issues in Europe and Asia. If you're having the instance physically housed in the UK and/or Singapore it can make a significant difference. That being said, there are some issues you'll need to plan for:
- Features. Making sure you're migrating over every feature which is going to be used on the European/Asian servers can be a non-mundane task. It may behoove you to run a program like this one in order to get a list of everything you need to push over:
An additional note about features: you might be paying for some, such as the Boost software. Unfortunately, they tend to be sold on a farm-by-farm basis, and so you'll have to buy new licenses in order to use them on remote farms.
Crawling / Federated search. You just plain can't crawl a SP farm of any size that's located in England from a farm in the US. It's going to take waaay too long and use up a crap-ton of bandwidth. Microsoft has some tools such as Federated Search to help you with this, and I believe 2013 has more robust federated options, but in 2010 I had to end up creating a custom solution involving the search.asmx web service that SP creates when you add an Enterprise Search Center to a web application.
Authentication. If you need to continue to have the farms communicate with each other (as with the search solution above, but also if you're utilizing BDC or Excel/Access services between the farms), you're going to have to have something more robust than NTLM or else you'll run into the double-hop issue. If they're already using FBA or what have you, great. If you're using NTLM, you'll need to "upgrade" to Kerberos. The good news is, your end users will see little to no difference between NTLM and Kerberos (if anything, they'll probably prefer it since Windows automatically passes authentication into SharePoint and as such they don't need to log in unless it fails). The bad news is, it can be a bit of a pain to set up on separate farms.
Links. SharePoint is made to use relative URLs for links. Really, the only time you should ever use an absolute URL is if you're linking to a non-SharePoint site. That being said, if your users are maintaining their own site collection, there is a strong chance that they will have put in absolute URLs to link to SP locations. You can warn them about the change, but be prepared to deal with this issue both before and after any switch.