Tuning DFS using ordering method in Namespace !

Hi there,

We have 2 servers (one in AUS, one in UK) and we are using DFS on the two for shared storage. They both are defined as 2 separate sites in AD Sites and Services and are in the  same domain.

Now we intend to add another server in AUS which will be part of the domain and will be in the same site as AUS (i.e. AD sites and services) and will be used for DFS shares. Intent is to make it a standby for the primary AUS one . How can I ensure that if the first one in AUS goes down, only then the users will access the DFS shares using the second server that was added in the site. What ordering method should I specify (Random, lowest cost or Exclude targets outside of the client's site) in the DFS to make it work like an active/standby between the 2 servers in AUS.

Accessing the shares over UK has been really slow from here so thats why in an event of an outage in primary AUS box, I want users to get redirected for DFS shares to this secondary AUS box.  

Hope I was able to explain my question clearly !
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bluntTonyHead of ICTCommented:
Actually you can set a preferred replica within a site. This is done in DFS management.

Browse to the folder, then right click the folder target > properties > Advanced Tab. Now enable 'Override referal ordering' and select 'First Among targets of equal cost'.

This makes this the preferred replica for it's site, but ifit goes down, another will be used.

Install AD on both servers and use lowest cost. Failover then can occur based on active directory site configuration.
there is a howto on configuration: http://help.globalscape.com/help/availl/Using_Microsoft_DFS_for_Failover.htm
I disagree with Libis - if the two servers are in the same site they will have the same cost, so there is no simple way to do what you are asking.  Workarounds you could try:

Create a separate subnet within your LAN for the secondary DFS server, create an additional Site in Active Diretory and assign a lower cost than the link to the UK.  Then use Lowest Cost ordering.


Disable referrals to the secondary DFS server.  Enable "Exclude targets outside of the client's site". In the event of a primary DFS server failure in Australia, manually enable referrals to the secondary server.

or (perhaps the best option)

Add the second DFS server as normal and use Lowest Cost ordering. Clients will be load-balanced between the two DFS servers and there will be less disruption if either server fails.  This solution is more reliable and will give you better performance.  Replication with RDC over a LAN will be near-instantaneous.

Let me know if you have any questions - there is more info about the DFS failover options here:

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I dont get the point why dicconb disagree with me :-) in your 3rd point he actually supposes exactly what I supposed to do. You can set cost in AD sites administration.
nabeel92Author Commented:
Thanks for the posts guys !

Libis, I haven't read the link you've sent me as yet but I think I maybe got what we're after. In AD Sites and Services, Sites --> Inter-Site Transports --> IP --> DefaultIPSITELink --> Right clicked and attached is the picture where it shows the option of adjusting the cost (Kindly ignore Parker). So, I guess I can have my new server added in the same site i.e. Sydney and then set the cost of existing Sydney server to 50 and the cost of new Sydney server to 100, then it will do active/standby rather than load-balancing which is what I'm after ? Correct ?  

Dicconb, I wanted the second SYD server to be in the same site as the first one is that we might use this server as a secondary Domain controller with the the existing one i.e. 1st Syd Server . In an instance where primary DC goes down, I was just thinking how it would affect the current AD users and computers if the this secondary DC was defined in a different site ? I'm not sure about its impact ... Will it make a difference  ?

bluntTonyHead of ICTCommented:
This is the R2 and later version of DFS....
Agree with Tony, that option is your best bet if you're running Server 2003 R2. Am embarassed I didn't think of it myself!
nabeel92Author Commented:
thnx all !
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