Tuesday, May 26, 2009

Using WSUS to save bandwidth, and how to set up an XP Home edition computer to use it

Two of the biggest challenges in keeping computers running in Africa are power and bandwidth. Bandwidth as in connection to the Internet, which is now vital for many of us. We're constantly trying to control and limit our bandwidth usage, which gets harder as people have higher and higher expectations. Our old-timers remember when we had to pay $0.50 a page to get emails that were sent over a noisy transatlantic phone connection to an expensive, 19 kbps Zyxel modem. Newcomers from developed countries are used to streaming video, Skype phone calls, file-sharing and so on.

One of the hidden consumers of bandwidth, though, is program updates. Keeping programs up to date is critical for security, but can consume a lot of bandwidth. For example, our network at SIM Nigeria serves roughly 40 computers (including laptops members bring to the office just to connect to the Internet). If a set of Windows updates is released that comes to just 10 MB, that translates to 400 MB to update all 40 computers, which is close to a whole day's bandwidth allocation for us.

Part of the solution is to use Windows Server Update Services (WSUS). This lets you download Microsoft updates onto a server on your network from which all your other computers can access them. Each update is downloaded once for the whole network, rather than once for each computer. You can read about WSUS and how to set it up here on the Microsoft Technical network.

An issue I encountered when trying to get as many computers as possible to use WSUS, though, is that XP Home (as opposed to Pro) edition does not include the policy-setting tool (gpedit.msc) normally used to instruct computers to get updates from the local WSUS server rather than over the Internet from Microsoft. Nor can you simply copy gpedit.msc from another computer onto the XP Home computer.

Instead, you can use a simple script to add some keys to the XP Home computer's registry. The script and explanation can be found at Guide For Setting Up XP Home Clients With WSUS. Just create a new text file, enter "REGEDIT4" as the first line, and copy and paste the registry keys as shown in that page. Change the two occurrences of "http://yourWSUS" to reflect the URL of your WSUS server. Save the file as "WSUS4XPHome.reg" (or whatever.reg) and run it on the XP Home machine. I think a simple reboot will suffice to start it looking for updates in the new location, but the page above tells how to use some commands to start the process immediately and without rebooting.

Reversing the process

You definitely do not want to leave these settings on a computer once it is no longer using your network for updates, since it will then fail to be updated at all. For computers joined to a domain that sets the group policy to use WSUS, it should be enough to remove them from the domain. For computers you manually changed (via local policy or registry changes) , you will have to undo those changes. As far as I know, you can simply delete the entire [HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate] key as it does not appear to exist in the default installation.

If anyone has corrections or further information, I would love to know.

Monday, May 18, 2009

Twe2 is gone, but then I never did get it to work

Earlier, I wrote about a service called Twe2 that allows people around the world to get Twitter messages on their mobile phones. That's needed because Twitter does not send to mobiles in most countries, only to the US, Great Britain, Canada, and, for some reason, India. Twe2 was supposed to be a gateway you could use to get around that limitation. Without something like it, Twitter is of limited use here (actually, I'm still trying to figure out what the use is).

I've tried many times to get my mobile phone number "verified" to work on Twe2, but for some reason the confirmation message would never come through. Perhaps a problem with my carrier. Whatever the case, it's now a moot point because I learned today from Twe2's website that it no longer exists, the source code having been sold to Wadja (an unfortunately heavy, clumsy sounding name in English, in my opinion, but what's a name).

temp I've signed up for Wadja (as MikeBlyth, in case you want to follow me) and am trying to get some friends in Jos to join so that we can test its capabilities. So far, I haven't seen anything about a gateway with Twitter, but we don't really need that if all we want is to access a Twitter-like network for our friends in Nigeria. I'll report later how it works. So far, all I can say is that the web interface seems really slow, at least from Nigeria.

Sunday, May 10, 2009

Disaster Avoided -- A Corrupted Microsoft Access Database File

I had a near miss today, almost losing my main address list, which I keep in Microsoft Access. I haven't used it in quite a while, as I have another list of recent address changes, but it's still my most comprehensive list of mailing addresses. When I tried to open it today, I got a message that it was in an "inconsistent state" and Access would try to repair it. Next, an error message that it "can't be repaired" or "isn't a Microsoft Office Access Database File."

I tried using my backup copies, but they had the same problem. It has been very long--4 years!--since I've put backups onto CDs or DVDs, simply because it takes so many of them, and have been relying mainly on one or two levels of medium term backups on an external hard drive.

Of course, this is far better than nothing, but the risk is just what I encountered today: having a file lost or corrupted and not knowing about it until the last "good" backup is gone. The same can happen with a virus. If you are keeping system backups but a virus has silently infected your machine, it could happen that all your backups are infected by the time you discover the problem.

I tried the solutions I found on the Microsoft site and by Googling, but they didn't work. The main thing I learned was that when your Access database is corrupted, there is a good chance that it's not something you can repair on your own. There are professionals who will do it, and some commercial programs. I tried one program, Advanced Access Repair, which quickly showed me that my data was recoverable. I was all ready to pay the $29.99 price of the program to actually recover the data, then noticed that the price is really $299.99. Oops.

Happily for me, the next program I tried was MDB Repair Tool, by Skysof, and it promptly repaired the database without my having to answer any questions or try different options. It just worked. To my surprise, this "trial" version actually recovered all the data for me for free, and I still have 58 more uses before I have to register. What a deal!

Lessons learned:

  • If you can't or don't want to save full backups to long-term media (DVD, CD, tape, or online), then you should at least save your most important data that way once in a while. This method is risky because you might miss data you should have backed up, but at least you will have most of what you need. (Be sure to include your email in your backup; it may not be included if you're not careful).
  • My address list doesn't need to be kept only in an Access database. I could periodically backup the actual address information so a simple text file. Then, if I lost the Access file, at least I would have the essential data.
  • Hopefully I won't ever have to repair another Access database, but if I do, MDB Repair Tool will be the first thing I try.