Planning for Huge Exhange Organization .Expected Mailboxes : 12000-15000Planning for CCR WITH SCR Sites : Two Sites connected with High speed bandwidth .Requirement : High Availability and smart solution .SITE A :Single Machine ------> Two Virtual Machines : Edge + Isa Server 2006 (DMZ )Single Machine ------> Two Virtual Machines :Hub Server + CAS(NLB AMONG CAS )Single Machine ------> Two Virtual Machines :Hub Server + CASMultiple Machines ------> Mailbox ServersSAN ------> EMC HIGHILY EFFICIENT AND FAULT TOLERANT .Maximum their are 10-15 databases but divided into four mailbox servers located into two different sites .Mailbox 1 :3 storage groups and single databse in eachdatabase:SG1-SG3databses: DB1 - DB3 : 120 GB EACHLOGS: 150 GBRSG : 150GBMailbox2 :3 storage groups and single databse in eachdatabase:SG4-SG6databses: DB4 - DB6 : 120 GB EACHLOGS: 150 GBRSG : 150GBDR Site for Site A : SCR Single Machine ------> Two Virtual Machines :Hub Server + CASMultiple machines for Mailbox Servers : having same configuration as source mailbox server have + San is also on DR Site A .SITE B:Single Machine ------> Two Virtual Machines : Edge(Backup MX ) + Isa Server 2006 (DMZ )Single Machine ------> Two Virtual Machines :Hub Server + CAS(NLB AMONG CAS )Single Machine ------> Two Virtual Machines :Hub Server + CASMultiple Machines ------> Mailbox ServersSAN ------> EMC HIGHILY EFFICIENT AND FAULT TOLERANT .Mailbox 1 :3 storage groups and single databse in eachdatabase:SG7-SG9databses: DB7 - DB9 : 120 GB EACHLOGS: 150 GBRSG : 150GBMailbox2 :3 storage groups and single databse in eachdatabase:SG10-SG12databses: DB10 - DB12 : 120 GB EACHLOGS: 150 GBRSG : 150GBDR Site for SiteB : SCR Single Machine ------> Two Virtual Machines :Hub Server + CASMultiple machines for Mailbox Servers : having same configuration as source mailbox server have + No SAN here.Question :my question is related to my design whether it is fine or it need some changes please advice ,second is that we have no SAN at site B so what is the recommended approach to site to site high availability,whether i have toplaced four target mailbox servers there in DRSITE Aas i have mentioned that i have no san in my site B,please advice in this regards .waiting for good reply .Thanks Syed Arsalansyed.arsalan

It's been a while. Is this still an open question? Have you completed the buildout?This type of post would be better if we could discuss the design one element at a time. Giving the whole thing a thumbs up or down is too broad a request. Also your details here are tough to follow.Here are some bullets I have, but by no means a comprehensive review:-how is the backup ISA server selected (in the event of a failure)? Is there a DNS based site selector or something else?-you said CCR but then also a SAN. these are typically opposite concepts as the whole point of CCR is to remove SAN dependency-you have 4 ht and cas, but only two with NLB?i cant really follow this db/sg design-you said scr. where is this?please be more specific with your questions so that we can supply better answers.