[wpkg-users] WPKG + Wireless Laptops
alan at adamshome.org.uk
Fri Feb 3 20:12:11 CET 2012
In message <4F2BF516.7070502 at pyther.net>
Matthew Gyurgyik <pyther at pyther.net> wrote:
> On 02/02/2012 04:18 PM, Alan Adams wrote:
>> 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.
> I appreciate your in-depth reply. It has brought up a lot a valid and
> helpful points. We are dealing, currently, with 4 laptop carts each
> containing 24 laptops. We have longer class periods (90 minutes). Just
> to deploy Firefox (10MB) to a set of laptops would take 45 seconds
> assuming ideal conditions (54Mbps). We have Wireless N access points,
> but realistically we likely wouldn't come close to that with all 24
> clients connected.
> From boot to login, it takes about 2-3 minutes. To add much more time
> to the login process would be frowned upon. Maybe, the best solution in
> this case would be to manually run wpkg from each machine to fetch new
> updates/software. Alternatively, I might be able to create an AD user
> that has a login script to call wscript. This way I could give said
> username to a few staff to help with this process.
The last is an interesting thought. Do you have staff who would be
willing/able to help you out? Great if so.
I'm heading down the "run at shutdown" route as the least-worst
option. If I implement that I will be expecting lots of phone calls
complaining that the computers won't shut down. Again the problem, as
you no doubt find, is that 30+ computers do the same thing
simultaneously, and wireless networks don't like that.
Alan Adams, from Northamptonshire
alan at adamshome.org.uk
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