It seems like just yesterday that Microsoft released SP1 for Exchange Server 2013 and yet CU5 (aka as SP1 plus first cumulative update) is out in the wild. As with all Exchange 2013 CUs the update is a FULL install of Exchange 2013 so the download is approximately 1.5GB in size. The good news is, unless you require maintaining older copies/versions of Exchange you can discard previous version as the latest and greatest DVD can be used for updating an Exchange Server or building an Exchange Server (that’s right, read slipstreamed).
There is a known “issue” with the latest release and the built-in Managed Availability Probe. Basically, you will see that the Exchange Share Cache Service restarts often because of an overly aggressive probe. Details of the issue may be found here but while the logging events are annoying, they are harmless. Your bigger issues may be where monitoring software starts to light up once CU5 is installed and if you do not want to modify the monitoring software, you can disable the probe (again in the KB article).
Be prepared for AD/schema updates when applying CU5 and as always, make sure the PS Remote Script Execution Policy is set unrestricted before installing the update (from an elevated PS prompt Set-ExecutionPolicy Unrestricted). Beyond the OAB improvements in distributed environments and the Managed Availability Probe bug, the remaining updates are basic fixes/updates to the existing code.
For Exchange 2010 SP3, RU6 is a basic update of bug fixes and updates to improve overall system stability.
Both updates have been applied to my labs with no issue and I suspect if all goes well the 2013 CU5 will be in my production in the next few weeks.
Lync Server 2010 build number is 4.0.7577.230
Lync 2010 Client build number is 4.0.7577.4445
Lync Server 2013 build number is 5.0.8308.577
Lync 2013 Client build number is 15.0.4605.1003
Lync Group Chat build number is 4.0.7577. 4409
Lync Group Chat Server build number 4.0.7577.4409
Lync Group Chat Admin build number 4.0.7577.4409
Lync Attendee build number is 4.0.7577.4356
Lync Attendant build number is 4.0.7577.4098
Lync Phone Editions build number is 4.0.7577.4444
Lync 2010 for Windows Phone build number 4.3.8120.0
Lync 2010 for iPhone build number 4.7
Lync 2010 for iPad build number 4.7
Lync 2010 for Android build number 4.0.6509.3001
Lync 2013 for Windows Phone build number 5.4.1087.0
Lync 2013 for iPad build number 5.4
Lync 2013 for iPhone build number 5.4
Lync 2013 for Android build number 5.3.1100
Lync Basic 2013 build number is 15.0.4420.1017
Lync VDI 2013 build number is 15.0.4420.1017