Difference between CCR and SCR
This is not a checklist of differences between CCR and SCR in Exchange 2007, but a main one I thought all should be aware.
Why do you think we should not implement 2 nodes in 2 different sites with CCR and forget SCR ? Just read through…
Standby Continuous Replication (SCR) in a nutshell is a type of clustering which allows you to replicate your production databases to a standby server that can be brought online if the active site/server goes down.
What’s different in CCR then ??? CCR offers high availability and site resilience too, but its best achieved via SCR. The main reason being, its complicated to implement CCR across datacenters that have different IP subnets, as the members of the CCR cluster must be in the same subnet with W2K3 OS. I wont say its impossible, but many organizations are looking at implementing SCR in a backup datacenter and then manually initialize the SCR servers for DR pupose for the production datacenter.
So, I would call this a main notable difference between CCR and SCR.
Ratish Nair
MVP Exchange
Team @MSExchangeGuru
August 4th, 2011 at 2:58 am
Hi
You are correct to a point but with 2003 R2 or sp2 removed this need to have CCR nodes on the same IP subnet. In my mind SCR offers other features which differentiate it from ccr.
1 SCR TARGET can be a standalone maibox server
2 SCR offers a capability to replicate one database to multiple target servers.
3 A administrative delay can be configured for raplay of log files into target database in addition to the dafault delay.
September 30th, 2011 at 4:02 am
What is the difference between LCR, CCR and SCR?
TweetThe following tables list the difference between LCR, CCR and SCC in Exchange 2007.
LCR
CCR
SCC
Failure or planned downtime of one node
No protection
Protected
Protected
Database corruption
Probable protected if database corruption is not replicated to the copy
Probable protected if database corruption is not replicated to the copy
No protection
Failed local storage system
Protected if second copy is on a different storage system
Protected
Protected if the failure is isolated to one node
Failed disk subsystem
Probable protected if second copy is on a different storage system
Protected
No protection
Data center failure
No protection
Probable protected if the second node is located in a second datacenter and the file share witness is accessible by it
No protection
Utilizes Windows clustering
No
Yes
Yes
Can use low cost storage systems
Yes
Yes
No
Storage requirements
Double
Double
Single
Backup databases without impacting server
Partial if the second copy is located on a different storage system the impact will be less. With CCR the primary server is not affected at all.
Yes
No
LCR
CCR
SCR
Support only one target passive copy
Support only one target passive copy
Supports multiple targets per storage groups
Can backup LCR Copy
Can backup CCR copy
Cannot backup SCR copy
Log shipping is Continuous and uses a PULL model
Log shipping is Continuous and uses a PULL model
Log shipping is Continuous and uses a PULL model
Does no use Windows Clustering
Uses Windows Clustering
Uses Windows Clustering
Double Storage requirements
Double Storage requirements
Single Storage requirements
SCR is similar to LCR and CCR, but it has unique characteristics of its own:
■SCR supports multiple replication targets per storage group. LCR and CCR support only one replication target per storage group (the passive copy).
■SCR includes a built-in delay for replay activity, and it enables an administrator to specify an additional delay. This is useful in a variety of scenarios. For example, in the event of logical corruption of an active database, the built-in and additional administrator-configured delay could be used to prevent logical corruption of an SCR target database. LCR and CCR have no such delays.
■SCR is completely managed using the Exchange Management Shell. The Exchange Management Console can be used to manage many aspects of LCR and CCR, but it cannot be used to enable or manage any aspects of SCR.