I was upgrading my Exchange 2007 SP2 to SP3, I have high available and site resilience server soles. My main issue occurred on Exchange Mailbox at DR site that is standby server (Standby Continuous Replication applied). The installation went fine and exchange setup log file did not report errors, however all exchange services was stopped and could not be successfully started. I have checked msi log file and it seems that many files of exchange are missed for example MSExchangeADTopolgyService.exe. I got the path from the service properties as snapshot below and I found that the file is missed, majority of other services were missing too.
My main concern is that I have 2 TB of exchange database that will need to be replicated from scratch again if I lost this server for ever. Thanks god the problem was limited to Mailbox at DR site only.
After searching I found that the solution is just re-install Exchange Service Pack (you need to remove rollup in case you installed it after SP installation).
The problem was resolved by run Setup again from the command line in the installation mode and installs the same roles that we were previously installing. The command used is Setup.com /m:install /r:mb