In reponse to Tony’s post about how much to serve users …

This is good stuff, Tony, but twelve values is probably too many. I try to simplify things down to three if at all possible.

1. Our default answer is “yes”. We always hope to find a way to meet the user’s need, even if it isn’t in quite the way the user expressed the need or quite the solution the user proposed. See: http://appianway.blogspot.com/2006/01/our-default-answer-is-yes.html

2. Our mission is our user’s mission. That is, when we’re working with Children’s Ministry, our mission is to teach kids about Jesus; when we’re working with Congregational Care, our mission is to visit people in the hospital; etc. Rather than focusing on our own mission, we’re focused on the mission of those we serve.

3. The one mission that is uniquely our own is information security. If we don’t look after information security, no one will. We define information security as providing or denying information access as appropriate and ensuring that critical information can’t be lost. If #1 or #2 above conflict with security, then we make a tradeoff.

We don’t always achieve our internal IT Department goals (roll out the software update by Feb. 1, upgrade environmental monitoring in the data center by the end of the month, etc.), but we always get high marks from our user community. As far as I’m concerned that’s the correct priority. And of course, we have to work very hard behind the scenes to make sure we don’t work exclusively on short-term or user-visible things. Sometimes the best thing we can do for our user community is to work on something that takes a lot of resources and users never know about. But that’s nothing fancy, it’s just good, disciplined execution.

From the number of comments on my Fall IT Roundtable Invitation, it seems like we’ll have a great group here in Kansas City for the Fall Roundtable. For now I just wanted to acknowledge all the responses. There will be a lot more information and discussion about the Fall event during the Spring Roundtable in Houston. We want to get feedback from the Spring Roundtable before we start posting more specifics.

Have a blessed Good Friday and Easter.

I posted earlier about the wireless LAN bridge we installed from our campus to our new leased office a couple of miles away.

These radios operate at such a high frequency (80 GHz) that nearly everything — a tree, a dense flock of birds, an errant golf ball (okay, I just made that one up) — is opaque to the signal. Consequently, they suffer from signal attenuation due to rain. This is a well-known phenomenon called “rain fade” that the RF engineers have to take into account in their designs.

We’re having some trouble getting sufficient path clearance (getting the base signal high enough) to avoid a link drop during periods of intense rain. Right now the base level is approx. -44 dBm. We were expecting rain fade of approx. 16 dBm, which should make it bottom out around -63 dBm. According to Bridgewave, these radios are supposed to be able to maintain the 100 Mb/s link down to -72 dBm. Therefore, we should have approximately 9 dBm of safety margin.

But we have two problems. First, we’re seeing rain fade of 22 dBm. Second, we’re seeing the link drop when the signal goes below -65 dBm. With 6 dBm more rain fade than expected and the link dropping 7 dBm before it should, our 9 dBm of safety margin is shattered.

Here is a graph showing two times when we had brief periods of intense rain. Each time the link dropped for a few minutes and then came back up after the intense rain passed:

After the the second drop you can see other periods of rain fade that weren’t intense enough to cause a drop. (The graph shows signal level in 100ths of a dBm. i.e. -4400 is -44 dBm.)

I gave a requirement of four 9s of availability (99.99% up time). Clearly, with the current base signal level, the amount of fade we’re experiencing, and the link drop level, we’re not going to be close to four 9s. Thankfully, we’re installing this well ahead of staff moving into the office so we have time to improve the situation. Also, I’m grateful that we’re installing in the Spring when we have rain every couple of days. Each time we make a change, we don’t have to wait too long before a real-world test presents itself.

We’re out there on the bleeding edge with this one! Please pray with us that this wireless LAN bridge story has a happy ending.