[wpkg-users] WPKG + Wireless Laptops

[Alan Adams]

In message <20120202090239.GC3059 at sv.lnf.it>
          Marco Gaiarin <gaio at sv.lnf.it> wrote:

> Mandi! Matthew Gyurgyik
>   In chel di` si favelave...

>> With a wireless laptop, will WPKG wait until the wireless connection
>> come ups to attempt to contact the server? If not, when do updates
>> get applied?

> On windows xpsp3 i use wireless machine authentication (so the network
> are setup before users login and after users logoff), and wpkg (with
> wpkgclient) works flawlessy.

You've picked up one of the biggest problems with respect to deploying 
software to laptops. In general they are only turned on and connected 
to the network when the users want to work on them, and pushing 
software out to them in the background can cause problems.

It is a particular problem in schools. A typical scenario is that of 
30 children collecting laptops, taking them to the classroom and 
switching them on. At this point there is a lot of network traffic 
associated with Group Policies being deployed. As soon as the login 
window appears they enter their credentials, and there is another 
burst of GPO traffic.

Somewhere in the middle of this wpkg starts downloading the 45MB MSI 
of Adobe Reader. Not content with that, it uninstalls the previous 
version, so it downloads that MSI as well.

You've now got 30 laptops downloading 100MB of data each across, in 
the best case, 2 33Mb/sec wireless shared links. 30,000 mbits, through 
66mbit/sec is 500 seconds, about ten minutes, ADDED to the normal 
startup and login time. Add the contention and retransmission overhead 
when the wireless gets saturated, and it can, and does, take an hour 
before the last pupil is logged in and ready to work.

Primary school lessons are typically 25 minutes.

Now I can see a way in the long term to reduce that. The wpkg script 
will copy the msi to a location on the hard drive, then run the 
msiexec command referencing the copy. No improvement this time round, 
but when it comes time to uninstall, it doesn't need to copy the msi 
again. That should give a factor two improvement. It will also help in 
deploying patch versions. To deploy 10.1.2 you deploy the 10.1.0 msi 
accompanied by the 10.1.2 msp. Combined, 65M. However the msi for 
10.1.0 would already be on the computer.

It also avoids the problem I've got at the moment. I deleted the Adobe 
reader 9.4.0 msi, then discovered some computers needed it for the 
uninstall when I deployed 10.1.2. (I don't know why they didn't get 
10.0.0, 10.1.0 etc...) This means that I now cannot deploy 10.1.2 to 
those computers, because the uninstall part of the process fails. 
Setting the flag in 10.1.2 not to uninstall doesn't help, because it 
simply refuses to install as another version is present.

I had to deploy Number Shark 4 last week. The msi is 450MB. Using 
wired connections it took around 15 minutes. Those using wireless, 
only 4 at a time, took almost an hour. Fortunately that school only 
has 30 laptops, so I managed to finish in a day. I had to pre-arrange 
that there would be no laptops available for the whole day though.

i have been hoping I could use wpkg, running as a service, to allow 
deployment during lessons. Using AD deployment simply prevents the 
lesson from starting. (I only have one day every 3 weeks in each 
school, so doing it out of normal hours is generally not possible.) 
However the issues described above are making me think it still isn't 
going to work.


-- 
Alan Adams, from Northamptonshire
alan at adamshome.org.uk
http://www.nckc.org.uk/