Microsoft has been using cumulative updates and service
packs with Exchange Server for some time. Starting with Exchange Server
2007, Microsoft began releasing customer rollup updates instead of
individual hotfixes. Here, each rollup contained one or more routine
product updates, one or more security updates, or both that were
delivered and applied in a single package. The goal was to simplify
delivery of updates and make maintaining Exchange Server easier.
However, because security updates were delivered with hotfixes in a
single package, you couldn’t install security updates separately from
hotfixes. Additionally, service packs for Exchange Server 2007 were
delivered as full product updates and installed as an upgrade.
Working with cumulative updates and service packs
With
Exchange Server 2013, Microsoft decided to deliver routine product
updates and security updates separately. Under this servicing model,
routine product updates are delivered periodically as a single,
cumulative update, and security updates are delivered separately. While
this allows you to install security updates as they are released
without having to install a cumulative update, cumulative updates
themselves will contain security updates. As with earlier releases of
service packs in Exchange Server, cumulative updates are delivered as
full product updates and installed as upgrades.
To better align on-premises Exchange and Exchange Online, Microsoft
tries to release cumulative updates on a fixed schedule and applies
cumulative updates to their hosted Exchange servers prior to official
release. Thus, when an update is released you know it has been applied
to all Exchange Online servers and all of the mailboxes stored in the
cloud.
Important
Microsoft is releasing cumulative updates for other products,
including Lync and SharePoint, on separate fixed schedules as well.
Ideally, this will be a quarterly release schedule with four cumulative
updates released each year during the product’s lifecycle.
Cumulative updates more closely resemble service packs than rollup
updates. Not only may cumulative updates contain hotfixes and security
updates, they may also contain new features, product enhancements, and
other changes that affect the way the product works. While language
modifications were previously limited to Service Pack releases,
cumulative updates may contain updates to language resources. A
cumulative update also may contain Active Directory schema updates. If
so, the schema changes will be additive and backward compatible with
previous release and product versions.
Important
Cumulative updates do not replace service packs. Microsoft will continue to release service packs for Exchange Server 2013.
Every cumulative update and service pack is a full release of the
product. This means, you install cumulative updates and service packs
as product upgrades and that each update package will be larger than
the previous product or update package. Because you install cumulative
updates and service packs as upgrades, any customizations you’ve made
to Exchange Server (using web.config files on Client Access servers,
EdgeTransport.exe.config files on Mailbox servers, registry changes, or
other custom configuration options on servers) are not preserved. This
means you will lose any customizations. To prevent this, you must save
your customizations and then re-apply them after applying a cumulative
update or service pack.
Real World
Don’t forget that it is possible the upgrade process will fail. If
this happens, you can recover from the failed upgrade like you would
recover from a failed service pack installation, which may include
running Exchange Server 2013 Setup with a special recovery option. To
do this, you enter the command SETUP /m:RecoverServer.
In
the unlikely event that the upgrade fails and is unrecoverable, you
will need to re-install Exchange Server. This re-installation process
will create a new server object and should not result in the loss of
mailbox or queue data. However, you will need to re-seed or re-attach
existing databases after the re-installation process.
Applying cumulative updates and service packs
You apply cumulative updates and service packs using Exchange Server
Setup. Because each cumulative update and service pack is a new build
of Exchange Server 2013, you don’t need to apply cumulative updates or
service packs in sequence. You can apply the latest cumulative update
or service pack at any time. For example, if you deployed Exchange
Server 2013 RTM but didn’t upgrade to Exchange Server Cumulative Update
1, you could upgrade the original installation directly to Exchange
Server Cumulative Update 2.
Important
When you are deploying Exchange servers, you don’t need to deploy
Exchange Server 2013 RTM and then upgrade to a cumulative update or
service pack later. Because each cumulative update or service pack is a
complete build, you can fully deploy the Exchange server using only the
current cumulative update or service pack.
In a Database Availability Group configuration, all servers should
be running the same cumulative update or service pack of Exchange
Server 2013—except during an upgrade. During an upgrade, individual
servers within a Database Availability Group can have different
cumulative update or service pack versions. This mixed state is
expected to be only temporary. Database Availability Group should not
operate in a mixed state for long periods of time.
Similarly, all servers in a Client Access array should be running
the same cumulative update or service pack of Exchange Server
2013—except during an upgrade. During an upgrade, individual servers
within a Client Access array can have different cumulative update or
service pack versions. Again, this mixed state is expected to be
temporary.
Cumulative updates and service packs are published at the Microsoft
Download Center. Because staying current with cumulative updates and
service packs may present a special challenge for some Exchange
installations, it is important to note that cumulative updates are
supported only for three months after the release of the subsequent
cumulative update. With Microsoft’s goal of delivering cumulative
updates quarterly, this typically means that a prior cumulative update
is supported for about six months.
Tracking Exchange Server version numbers
Versioning with Exchange Server 2013 gets a little tricky. This is
because Exchange Server can have both service packs and cumulative
updates for those service packs. To differentiate between versions,
Microsoft references both the Exchange Server version and the
cumulative update.
The official release of Exchange Server 2013 is referred to as
Exchange Server 2013 RTM. Cumulative updates for this release are
referred to using the full release name plus the cumulative update
number. Thus, Exchange Server 2013 RTM with Cumulative Update 1 is
referred to as Exchange Server 2013 RTM CU1.
As Microsoft releases
service packs for Exchange Server 2013, those service packs will be
full product rollups that include prior cumulative updates of the
product. Cumulative updates for Exchange Server 2013 with specific
service packs will be released as well. In this instance, cumulative
updates are referred to using the full release name, the service pack
name, and the cumulative update number. Thus, Exchange Server 2013 SP1
with Cumulative Update 1 is referred to as Exchange Server 2013 SP1 CU1.
Keep in mind the version of Exchange Server is updated when you
install a cumulative update, a service pack, or both. This means that
one way to determine what cumulative update, service pack, or both is
applied is to check the version number of an Exchange server. The build
number for Exchange 2013 RTM is 516.32; the build number for Exchange
2013 RTM Cumulative Update 1 is 620.29; the build number for Exchange
2013 RTM Cumulative Update 2 is 712.22, and so on.
Real World
The Exchange 2013 management tools make it easy to determine version
numbers. In Exchange Admin Center, simply select Servers in the feature
pane and then select Servers to see a list of Exchange servers by name,
install roles, and version. In Exchange Management Shell, you can
display a similar list by entering the following command:
Get-ExchangeServer | select name, serverrole, admin*
Using security updates with cumulative updates and service packs
The servicing model changes the way security updates are released as
well. For Exchange Server 2013, security updates are designated for a
specific cumulative update and contain all of the fixes available at
the time of release in a single update package. Thus, to ensure a
server has the most recent security fixes, you need to apply only the
most recently released security update for a specific cumulative
update. For example, if you are using Exchange Server 2013 with CU2,
you ensure a server has the most recent security fixes by applying the
most recent security update for CU2.
As cumulative updates themselves contain security updates, you need
to apply only security updates that have been released after a
specified cumulative update. Thus, if for some reason you didn’t apply
security updates for Exchange Server 2013 CU1 and have now upgraded to
Exchange Server 2013 CU2, you don’t need to apply any of the security
updates that are specific to Exchange Server 2013 CU1 (or Exchange
Server 2013 RTM).
Security updates for Exchange Server 2013 are available via
Microsoft Update and are published at the Microsoft Download Center.
Finally, it is important to point out that security updates released
for a particular cumulative update will not need to be uninstalled
before moving to the next cumulative update.
New
service packs for Exchange 2013 will include all the prior cumulative
updates and security updates. Thus, when you install Exchange 2013
Service Pack 1, you don’t also need to install any prior cumulative
updates and security updates.
