I have my main computer as Solaris dual boot with Windows 2008, to keep it updated I recently booted into Windows to install SP2.

After some time downloading, asking me to quit everything and rebooting a few times the installation failed at 100% at Stage 3 with the following message:

Installation was not successful 

Unspecified error 

Error: E_FAIL(0x80004005)

Sigh, how hard is it to write in English or to check for certain parameters before installation?   This is one reason why I love Solaris/OpenSolaris, you can have multiple boot environments and update them while using another one.  Then the only downtime is a reboot to enable and switch to the new boot environment.

At work they have implemented it and it has reduced the possible downtime from 6 - 8 hours down to 2 - they still allow this much time in case of any issues.

After much searching, I finally found our that for SP2 to install on Windows 2008, it needs to be on the active partition . . . so after a quick change with Disk Management SP2 successfully installed.

Then it was a quick boot into failsafe Solaris to make the Solaris partition active again. 

All updated!

Source/Kaynak : http://blogs.sun.com/thinslice/entry/windows_service_packs_there_must