Implementing Central search on a multi region farm setup

Question

We are setting up a multi region SharePoint Server 2010 farm with a Central farm and 3 regional farms. In order to provide Central search from the Central farm ( i.e. search returning results from all regions )

we have come up with the following options.

Option 1 : Share the search service application across the farms

We can create Search Service Application in the Central Farm and publish it to be shared across the farms. The other regional farms will consume the search service application.

Option 2: Providing Content Source details

We can directly provide the following content sources in the Search Service application of the central farm to crawl. i.e (a) web app url from regional farm a, b, c

Both of these options work fine and return search results as expected. We need advise on the above options for Central search in terms of best practices.

Answer 1

It is isn't a matter of best practices since these are two different things. You have decide which is better for your situation. In option A, you only have 1 search service application so there is less physical things for you to manage. This also means the regional farms can be smaller and cheaper since they don't need to run search. This also means that the regional farms are beholden to the central farm for search so it always needs to be available.

In option B, you have multiple search applications to manage so there will be a certain amount of redundant effort involved. Also, since items will be in the regional search indexes as well as the central search index there will be some measure of duplicated data stored. the advantages however is that these environments have fewer dependencies and therefore you can have different SLAs or maintenance periods.

The choice is really up to you to optimize the characteristics that matter to you most.