I am trying to figure out when computers actually download the updates.
The download is normally initiated immediately after the WUAgent detects
that an update is approved on the WSUS Server. Functionally, this can occur
at any time of day, since the default detection interval is 17-22 hours,
meaning each detection is significantly less than 24 hours since the last
one, resulting in, ultimately, clients synchronizing throughout the day, and
each client at a different time each day.
My downloads were failing at 1:58 AM, when I set the wake-up time for 1:55
The issue here being the assumption that you have control over the time of
the download. You don't. The download is triggered by the existence of an
update approval discovered during a detection,which occurs around the clock.
so I set the wake-up time for 1:45. Now the downloads fail at 1:48.
The bottom line here is that the download is failing. The question is
whether the download was attempting to resume after having been 'put to
sleep' by the OS, or whether this was an original download initiation caused
by a detection which occurred in response to the Wake-On-Lan.
If I knew when the download wanted to start, I could adjust my Wake-Up
time to accommodate the download time.
Except you cannot do this in any scenario.
I have not found any documentatio about when the downloads start for the
default install time.
It's not documented, per se. In fact, one of the great deficiencies in the
entire WSUS infrastructure scenario is the severe dearth of documentation on
the Windows Update Agent. However, a quick inspection of any
WindowsUpdate.log will reveal the truth of the matter. Downloads are
initiated immediately after the initial detection of an approved update.
At best you can use Wake-On-Lan to wake up systems for the scheduled
*installation* time, when the machines have updates to install, provided
that the download of the update(s) has successfully concluded before the
machine is put to sleep. Downloads, however, need to occur during normal
Lawrence Garvin, M.S., MCITP:EA, MCDBA
Principal/CTO, Onsite Technology Solutions, Houston, Texas
Microsoft MVP - Software Distribution (2005-2009)
My Blog: http://onsitechsolutions.spaces.live.com
Microsoft WSUS Website: http://www.microsoft.com/wsus
My MVP Profile: http://mvp.support.microsoft.com/profile/Lawrence.Garvin