Lori MacVittie has an excellent article on passive host monitoring in an F5 Big-IP environment. Introduced in v10, BIG-IP load balancers now support something called Inband Monitoring. This basically sniffs the traffic, and responds based on the rule you define. Lori put an example up which looks for the HTTP error codes above 500, and after 3 errors seen in the responses, it marks that host as unavailable. This is a great feature as it doesn’t add any load to the web servers with active checks, and if you have ever looked at a host that i s behind a load balancer, log analysis can be a pain. The cool thing is, after the host has been disabled, the passive check can enable your regular active checks to bring the host back up when the issue is resolved. Some excellent stuff.
The Nubby Admin has a great post on uptimes, and the old fascination of having a large uptime. Okay, you can get your minds out the gutter now, not that kind of up time. We’re talking servers here.
The post covers a hidden fear, and the goods and bads of large server uptimes. A good read, and one you should look at if you’re watching your server rolling over into the third year of being running. I get a mention (well more of a quote), and seem to fall in with the general crowd, large server uptimes are generally bad.
Go read, enjoy, learn something new from the great minds Wesley is surrounding himself with (myself excluded).
Digging up an old post today, I helped my wife figure out why her office A/C system couldn’t be managed properly. Apparently their system connects on a specific IP address, and it wasn’t responding. It was surmised that it was caused by some work I had done fixing one of the other machines a few months ago. But after some quick digging, turns out it wasn’t. Apparently their “consultant” had a device on the network for VPN, firewall, etc, which had the same address on it. How it got the same, we don’t know, but here is how we figured it out…
Read more…
PacketLife as an excellent collection of cheat sheets for networking professionals. Well worth a quick look and bookmarking for later.
