Interesting thing of the day: Milo, Ron, et al. “Network motifs: simple building blocks of complex networks.” Science Signalling 298.5594 (2002): 824. Fulltext available from Google Scholar: - http://bit.ly/YAstgD It occurs to me that in scalable systems engineering (the sort of thing I do for a living), you only tend to see Bi-fan networks and Bi-parallel ones. Bi-fan is rougly equivalent to a cross-connected core switch whereas Bi-parallel is a good representation of a Virtual IP with Load balancer. ...

I think this seems like an appropriate time to say a few words in favour of the great United States of America. There’s some things they just do excellently. Customer service springs to mind as one of the best I’ve ever encountered. I’m not exactly sure why this is, but people do seem to be far more willing to be kind, courteous and helpful. There’s other things too, the weather is, generally better (and if not better, then certainly more predictable). There’s also the stunningly beautiful scenery. I challenge anyone to gaze deeply at the Grand Canyon, or the Yellowstone Paint Pots and not be stricken with a sense of awe and grandeur. ...

I’ve heard quite a bit about the “G-WAN Application Server” over the past few weeks. Initially it was a Serverfault question that left me thinking “WTF” (http://serverfault.com/questions/445835/virtual-host-on-g-wan) I took a look at their website and thought: “Those are pretty insane claims”. They’re also the kind of crap you tend to see where the intended audience is somebody who has absolutely no clue about scalability, or production-readiness. Y’know, Managers. Quite well summarised by this comment: GWAN isn’t designed to be a robust webserver, it’s designed to perform exceptionally well in contrived and outlandish benchmarks, so PHBs will demand the IT team use it and buy support… – Chris S♦ 19 hours ago Interestingly enough, the only person who answered that question was a fellow called Gil who apparently works for G-WAN.. I don’t normally take much offense to product owners on Serverfault et al, but the vast majority of his answers do seem to be a bit spammy. ...

I’m looking to setup a site with 49 edge switches connected by fiber to a central switch. 3 VLANs will be setup to handle data, telephony, and streaming media. each edge switch should have provision for 2 SFP modules for failover, and the core switch needs to have the provision to handle this failover. i’m getting lost on the Cisco site with their specs and recommendations. if anyone could suggest a suitable model number for the core switch and the edge switch, it would be really appreciated.” ...

This is a bit long-winded, and wordy. If you’ve come here looking for tips on improving commvault backup performance and/or throughput, then you should click here for the good stuff. It’s been a long time since I blogged. It’s been a really long time since I blogged about anything we’ve been doing at $Dayjob. I’ve spent the better part of the year working on sorting out the backup solution here. ...

Lessons learnt from the Unlock London Hackathon. I had an email on May 16th, asking for some assistance in setting up the wifi network for another hackathon. After my impromptu assistance at LondonRealtime went down so well, and “saved the network”; apparently I was a natural choice for the next one. At least I knew (sorta) the network layout at White Bear Yard. The main difference between this one and the last, was a bit more warning on the side of “We’re gonna need wifi”, but there was still a clause that it’s gotta be “flawless” - Their words, not mine. ...

As time goes on, and I find myself dealing with more and more large companies, it’s pretty obvious that there’s a recurring pattern. Many large companies are awful to work with. Dell are pretty bad. On one recent occasion, we had the need at work to call Dell Support for a mysterious problem with our shiny new blade servers. The biggest problem when dealing with Dell in particular is their scripted support technicians on 1st line. Most other companies seem to hire people with the capability of abstract thought. Dell hires chimpanzees to read from scripts. Woe befalls you if you attempt at any point to deviate from the script, and heaven forbid you ask a question that they don’t have the answer to. If that happens, there’s a 1 in 3 chance of any of the following outcomes. ...

Smokeping is one of my favourite diagnostic tools for tracking down sporadic network issues. You install it, configure it with a list of hosts, and it pings them regularly, and keeps track of the round-trip times, latency, packetloss, and so on. The web frontend is a Perl CGI script, and as a result, it’s a bit of a bugger to make it work on Nginx. I wasn’t gonna install Apache just for this one thing… ...

Does this look suspicious to you? 85.25.184.184 - - [13/Mar/2012:00:41:09 +0000] "POST /3293b4da67abffca2460244619d9a8bca3f4c401.php HTTP/1.1" 200 1096 "-" "Mozilla/5.0 (Windows; U; MSIE 9.0; WIndows NT 9.0; en-US))" 85.25.184.184 - - [13/Mar/2012:00:42:57 +0000] "POST /3293b4da67abffca2460244619d9a8bca3f4c401.php HTTP/1.1" 200 359 "-" "Mozilla/5.0 (Windows; U; MSIE 9.0; WIndows NT 9.0; en-US))" 85.25.184.184 - - [13/Mar/2012:00:42:57 +0000] "POST /3293b4da67abffca2460244619d9a8bca3f4c401.php HTTP/1.1" 200 450 "-" "Mozilla/5.0 (Windows; U; MSIE 9.0; WIndows NT 9.0; en-US))" 85.25.184.184 - - [13/Mar/2012:01:14:12 +0000] "POST /3293b4da67abffca2460244619d9a8bca3f4c401.php HTTP/1.1" 200 354 "-" "Mozilla/5.0 (Windows; U; MSIE 9.0; WIndows NT 9.0; en-US))" Sure as hell looks dubious to me. Looks like something doing something that it oughtn’t. ...

This is a continuation to my earlier blogpost about hacking initrd.gz. After it’s installed with the modified installer kernel, and finished building, the installed kernel doesn’t have the e1000e driver. This is because the netboot installer pulls in a kernel and it’s wherewithall from apt. It also gets a new initrd. As a result, I’ve decided to build an e1000e-dkms module, and we’ll specify the preseed installer to install that, along with linux-headers-generic, linux-headers-2.6.32 and build-essential. ...