GUIDELINES FOR SITES WITH < 512K AVAILABLE DATA-ONLY TO DC PROMO

      I would like to share the GUIDELINES FOR SITES WITH 512K AVAILABLE DATA-ONLY CONNECTIONS and PROPOSE TO DC PROMO THIER LOCAL DCs. For sites which plan to install and promote (locally) an AD domain controller, a 512K available Data-only connection is the strong recommendation. And the only connection I am quite confident will succeed and not require additional support and effort.   If the site has a link lower than that, additional research needs to be done to ensure a smooth promotion and to minimize adverse business impact.

      My recommendation that we feel comfortable with. is 512K data only.  Anything under that, we may be able to try, but unfortunately, we cannot guarantee anything.  So it is up to the site to determine if they want to take on that risk.  For example, if a site’s circuit is going to be upgraded later anyway, they may want to wait.  Unless there's a business case that indicates a site cannot wait.

Considerations:
       Those at the site representing the business must understand and agree to the additional risk, should they elect to promote a DC over a <512K available data-only  link, which includes:

• Very very slow connections to external resources, including applications, internet, etc. for a week or more.  They should expect 3 weeks.
• A successful promotion at a similar site does not ensure other similar sites will be successful.  Because every site is different, and the databases increase daily.

Here are the rules:
       If a site MUST DC Promo over a smaller (than 512 available -  meaning part of the link isn’t dedicated to some other data stream like Mail, ERP, etc.-   data-only) or shared link,  the Server Infrastructure Team needs to talk to them to gather important information.

• It is critical that the design teams understand what is going over the connection, so we can make an informed decision.
• When promotions fail, it causes rework and could delay other sites.   Also, the rework always introduces some small amount of risk that something inadvertently corrupts the rest of the forest. 
• Once we all understand what is going over the <512K link, the customer agrees to the risk, and the Server Infrastructure Team design team feels it will not adversely impact others, we can OK the attempt at a DC promotion.  Again, the site will be expected to significantly reduce any other traffic going over the link during the promotion, and also during the SMS build. Traffic what should be taken into consideration, and significantly curtailed includes:
        • voice traffic
        • external application traffic (like intranet, ERP)
        • Internet traffic
        • Promotions must start the Fri just before a weekend to ensure the best throughput.
        • Promote the DC at a well-connected site, and then ship to the other site whenever possible.
• We can't make a lot of special allowances trying to make it work, If it promotes, it promotes.  And if it doesn't, it doesn't.  In many cases, we can try it, if the customers willing to take on the risk. And once all servers come up on site, we cannot be certain there will be no performance degradation when servers try to sync etc….  Again, there are too many variables. 

      We need to address and agree to the plan for <512K available data-only sites well in advance of their planned DC promotions.  That way, things can run as smoothly as possible.