Strictly speaking no; but a CAS array is pretty mandatory if you want to have high availability on your databases. Otherwise, each time you want to reboot a CAS, or your CAS fails, you'll need to change the RpcClientAccessArray parameter on each EDB before your users can work.
The bottom line is a CAS array is free, easy to configure and doesn't need any maintenance. Even if you only have one CAS, do it anyway. From: bounce-9551889-8066...@lyris.sunbelt-software.com [mailto:bounce-9551889-8066...@lyris.sunbelt-software.com] On Behalf Of Al Rose Sent: 28 September 2012 16:09 To: MS-Exchange Admin Issues Subject: Re: Design question Exchange 2010 Well you can create web farms in TMG, this is not load balancing but CAS Array is not load balancing either On Fri, Sep 28, 2012 at 4:05 PM, Steve Goodman <st...@stevieg.org<mailto:st...@stevieg.org>> wrote: The CAS Array is used for RPC Client Access i.e. MAPI, which TMG won't load balance. Steve From: Al Rose [mailto:arose...@gmail.com<mailto:arose...@gmail.com>] Sent: 28 September 2012 14:55 To: MS-Exchange Admin Issues Subject: Re: Design question Exchange 2010 Just wondering, if i can create a web farm in TMG that points to my 2 cas servers, why would i also need to setup a cas array? On Thu, Sep 27, 2012 at 1:11 PM, Al Rose <arose...@gmail.com<mailto:arose...@gmail.com>> wrote: Thanks for the feedback all, i understand the point of adding the HUB role and also CAS so i will go ahead and add them to the box. I also will add one DC in the second Data Center this sounds like a good idea :) I don't have the possibility to use a Hardware Load Balancer, so our design will allow for Server Disaster Recovery but not Site Disaster Recovery, this is because we only have one entry point from the Internet to one of our data center. This Entry point is actually located to the remote Data center, we have an ASA Cisco firewall followed by a TMG Forefront server which do reverse proxy for our Exchange 2003 OWA, ActiveSync and RPC. We then have a routed connection to our office Data Center (extended VLAN) which contains the current mail server. So i am still unclear what would be the good option about the CAS design here (having 2 exchange server CAS/HUB/MAILBOX participating in DAG). Because we will mostly have around 200 Users mailboxes, we don't need load balancing as such to distribute the load. The benefit of having 2 servers would eventually be to allow a server to go down for installing updates. But i just feel we should only use one active CAS server (the one close to the Forefront server) and have the other one as a Standby just in case the other is rebooting after updates have been installed,...Is TMG here my best friend here? I would say, i would create a CAS Array but have TMG reverse proxy to one server only. Or don't create a CAS Array at all and change the CAS array on TMG publishing rules when needed? On Tue, Sep 25, 2012 at 4:18 PM, Dave Wade <dave.w...@stockport.gov.uk<mailto:dave.w...@stockport.gov.uk>> wrote: I must admit I don't understand the logic behind this setup. So let's look at a few basics:- 1. In Exchange 2010 ALL mail flows through the Hub Transport Role so if you want to send mail in your DR site you need an HT role in the DR site. 2. A DAG uses MSCS failover clustering under the covers (so it needs Enterprise edition of windows). If it can't see the witness share things get mildly interesting. To get round this you can use Av mode and an alternate witness share, but that requires manual fail over of the share which may not be what you want. http://technet.microsoft.com/en-us/library/dd979790.aspx 3. According to:- http://technet.microsoft.com/en-us/library/dd638104.aspx you need a CAS in each site to manage the failover. 4. If you are happy to have to manipulate the DNS to manage failover then it is OK to have a standby CAS but I get the feeling the Exchange designers kind of expects you to have a Client Access Array with some kind of automated failover. Dave Wade 0161 474 5456 From: Al Rose [mailto:arose...@gmail.com<mailto:arose...@gmail.com>] Sent: 25 September 2012 12:04 To: MS-Exchange Admin Issues Subject: Design question Exchange 2010 Hi, I am looking on some design feedback regarding what we are about to do in our ORG. We are going to consolidate our mail infrastructure, from regional Exchange 2003 servers to one central Exchange 2010 server. We have very few users in regional offices, so there is no need anymore for dedicated Exchange servers. Our central Exchange server is going to hold all Exchange roles, users are going to access it through a TMG Forefront server. We also have an available Data center space which we plan to use for setting up another server (mailbox role only) so to use DAG and replicate all mailboxes for disaster recovery. Would it make sense here to introduce another CAS server in the Data center as to provide fail over in case one site goes down, would that server also need the HUB role installed? We really would like to have users use only one CAS server but i was thinking another could be set as a standby one, is that feasible? All servers Site A and Site B can share the same subnets and AD site. Thanks --- To manage subscriptions click here: http://lyris.sunbelt-software.com/read/my_forums/ or send an email to listmana...@lyris.sunbeltsoftware.com<mailto:listmana...@lyris.sunbeltsoftware.com> with the body: unsubscribe exchangelist Do you know someone who makes you Proud of Stockport? Is there someone who goes out of their way to make our borough a special place? Then nominate them for an award in our 2013 citizen awards by going to www.stockport.gov.uk/proudofstockport <http://www.stockport.gov.uk/proudofstockport> Entries close on Friday 26 October. Confidentiality:- This email, its contents and any attachments are intended only for the above named. 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