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Reasons to love Exchange 2013 High Availability Steve Goodman Exchange MVP Senior Consultant at Ciber UK Twitter - @stevegoodman Email – [email protected] Web – www.stevieg.org
Reasons to love Exchange 2013 High AvailabilitySteve GoodmanExchange MVP Senior Consultant at Ciber UKTwitter - @stevegoodmanEmail – [email protected] – www.stevieg.org
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Reasons to love Exchange 2013 HA This evening we’ll cover a few great features that I think make Exchange 2013 a no brainer
It’s an informal session so feel free to add your point of view and favourite features!
Let’s start with a brief history of Exchange HA…
Evolution of HA in ExchangeA very brief history
Evolution of HA in Exchange
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Exchange 2003
Exchange 2007
Exchange 2010
Exchange 2013
Five great new HA features
1. No CAS session affinity
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No CAS session affinity required Clients can connect to any CAS and remain connected to the same session
Requires the same SSL certificate on each CAS
Builds on the every server is an island principle
Makes load balancing much simpler
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No CAS session affinity required
Client AccessServer
MailboxServer
Client AccessServer
MailboxServer
OWA Rendering
MailboxServer
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3
2
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1. HTTPS OWA Request to Client Access Server is authenticated and cookie is encrypted using SSL certificate.2. HTTPS Reverse Proxy to Mailbox Server where OWA is rendered and Mailbox is Active3. Authentication cookie is presented to second Client Access server and successfully decrypted.4. HTTPS Reverse Proxy to original Mailbox Server
2. Unbound Namespaces
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Unbound Namespaces Site Resilience typically required lots of names
Unbound allows you to have a single name across multiple sites (i.e. not bound to a site)
Use no affinity round robin to balance across Load Balancer VIPs
Although not essential, Geo DNS can ensure clients stay in-region
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Unbound Namespaces
Contoso.com AD Forest
emea.mail.contoso.comus.mail.contoso.com
EMEA Mailbox User
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Unbound Namespaces
Contoso.com AD Forest
mail.contoso.commail.contoso.com
EMEA Mailbox User
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Unbound Namespaces
Contoso.com AD Forest
mail.contoso.commail.contoso.com
EMEA Mailbox User
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Unbound Namespaces
Contoso.com AD Forest
mail.contoso.commail.contoso.com
US Mailbox User
3. Two and a half sitesAKA File Share Witness in a Third Datacentre
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Third Datacentre File Share Witness Even number DAGs use a File Share Witness to maintain quorum
In Exchange 2010 a typical deployment included a primary File Share Witness in the Primary DC, and Alternative FSW in a secondary DC.
As part of Site Resilience procedures, the Alt FSW would be activated manually
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Third Datacentre File Share Witness
Datacenter 1 Datacenter 2
Database Availability Group
File ShareWitness
Exchange DAG Node 1
Exchange DAG Node 2
Alt File Share Witness
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Third Datacentre File Share Witness Exchange 2013 allows a third datacentre to be used for the File Share Witness
This must be well connected to both datacentres
In the event of a single DC loss, quorum is not lost
Azure IaaS may be supported in the future
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Third-Site File Share Witness
Datacenter 1 Datacenter 2
Database Availability Group
Exchange DAG Node 1
Exchange DAG Node 2
Datacenter 3
File ShareWitness
4. Dynamic Quorum
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Dynamic Quorum Part of the Windows Clustering Stack and introduced in Server 2012 and enabled by default
Effectively allows the DAG to continue operating even after the point it would normally lose quorum, even down to a single node
Helps to withstand planned shutdowns
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Dynamic Quorum
Datacenter 1 Datacenter 2
Database Availability Group
File ShareWitness
Exchange DAG Node 1
Exchange DAG Node 2
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Dynamic Quorum
Datacenter 1 Datacenter 2
Database Availability Group
File ShareWitness
Exchange DAG Node 1
Exchange DAG Node 2
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Dynamic Quorum
Datacenter 1 Datacenter 2
Database Availability Group
File ShareWitness
Exchange DAG Node 1
Exchange DAG Node 2
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Dynamic Quorum
Datacenter 1 Datacenter 2
Database Availability Group
File ShareWitness
Exchange DAG Node 1
Exchange DAG Node 2
1 2
5. Database Auto Reseed
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Database Auto Reseed JBOD has been supported since Exchange 2010 and is a foundation for Exchange Native Protection
The theory is you have enough Database Copies to remove the need for hardware RAID
In Exchange 2010, a failed disk must be partitioned mounted and formatted, then the database must be reseeded manually and progress monitored
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Database Auto Reseed Database Auto Reseed complements technologies including JBOD, multiple databases per volume and loose truncation
The DAG is designed with online spare disks and mount points for both databases and volumes
In the event of a disk failure, the spare disks are automatically brought online and databases reseeded from other copies
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Database Auto Reseed
Exchange DAG Node 1
Exchange DAG Node 2
Exchange DAG Node 3
DB1 DB2 DB1 DB2 DB1 DB2
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Database Auto Reseed
Exchange DAG Node 1
Exchange DAG Node 2
Exchange DAG Node 3
DB1 DB2 DB1 DB2 DB1 DB2
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Database Auto Reseed
Exchange DAG Node 1
Exchange DAG Node 2
Exchange DAG Node 3
DB1 DB2 DB1 DB2
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Database Auto Reseed
Exchange DAG Node 1
Exchange DAG Node 2
Exchange DAG Node 3
DB1 DB2 DB1 DB2DB2DB1
How are these features used in Office 365?
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How are these features used in Office 365? Microsoft run Office 365 in 26 locations, worldwide
Over 125,000 Mailbox Databases, thus.. Over 80 DAGs Over 1200 Exchange Servers Potentially a lot more DAGs and servers
Global scale requires automated recovery from failures and simplicity where possible
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How are these features used in Office 365? Round robin DNS used for no session affinity when accessing outlook.office365.com
An unbound namespace along with geo-DNS used for outlook.office365.com
A third site out of region is used for every Exchange Online DAG
Dynamic Quorum is on by default in Office 365
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How are these features used in Office 365? Dynamic quorum is used by default in Office 365 to help increase availability
Database Auto Reseed was born in the service as it becomes impossible to manually change disks, then perform and monitor reseeds at global scale
Putting it togetherYes, you can try this at home!
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Putting it together You can design a super resilient architecture that can service datacentre failures with little to no customer impact
Microsoft’s Preferred Architecture provides the best starting point when thinking about the best way to put this together
