The convoy phenomenon

The convoy phenomenon Blasgen et al., IBM Research Report 1977 (revised 1979)

Today we’re jumping from HotOS topics of 2019, to hot topics of 1977! With thanks to Pat Helland for the recommendation, and with Jim Gray as one of the authors, we have a combination that’s very hard to ignore :).

Here’s the set-up as relayed to me by Pat (with permission):

At work, I am part of a good sized team working on a large system implementation. One of the very senior engineers with 25+ years experience mentioned a problem with the system. It seems that under test load, it would behave beautifully until the performance just fell to the floor. The system just crawled forever and never seemed to get out of this state. Work was getting done but at a pathetic rate. I said: “You have a convoy.” His response was; “Huh?”. I forwarded him the paper on “The Convoy Phenomenon”…

I have to confess I hadn’t heard of the convoy phenomenon either! Before we go on, take a moment to think of possible causes for the system behaviour described above. Lots of things can cause a performance cliff, but the interesting thing Continue reading

Response to “Certifications Are Not A Big Deal. Stop Being a Princess About It.”

In a post which now appears to have been deleted, Greg Ferro got right to the point in his article Response: Certifications Are Not A Big Deal. Stop Being a Princess About It.. The majority of this response was written while Greg’s post was still active, but I had to come back and inject more context after I spotted on June 30, 2019 that the post had become unavailable.

To save you digging in the WayBackMachine, the history to Greg’s post as I understand it is that Greg made some comments in Episode 238 of the Packet Pushers’ Network Break suggesting that vendor certifications were trivial. A listener evidently gave some strong feed back disagreeing with this, and so in Episode 239 of the Packet Pushers’ Network Break Greg responded to that feedback, and reiterated his position about certification study, specifically framed around Cisco’s CCNP. Greg made some reasonable points; that the certification programs from the vendors are not designed to teach fundamentals in the same way that, say, a computer science degree might do, and that the aim is really to make money for the vendor, and reduce their tech support costs, and as such the vendor certification education Continue reading

Third Time’s a Charm (A brief history of a gay marriage)

Third Time’s a Charm (A brief history of a gay marriage)

Happy Pride from Proudflare, Cloudflare’s LGBTQIA+ employee resource group. We wanted to share some stories from our members this month which highlight both the struggles behind the LGBTQIA+ rights movement and its successes. This first story is from Lesley.

The moment that crystalised the memory of that day…crystal blue afternoon, bright-coloured autumn leaves, borrowed tables, crockery and cutlery, flowers arranged by a cousin, cake baked by a neighbour, music mixed by a friend... our priest/rabbi a close gay friend with neither  yarmulke nor collar. The venue, a backyard kitty-corner at the home my wife grew up in. Love and good wishes in abundance from a community that supports us and our union. And in the middle of all that, my wife… turning to me and smiling, grass stains on the bottom of her long cream wedding dress after abandoning her heels and dancing barefoot in the grass. As usual, a microphone in hand, bringing life and laughter to all with her charismatic quips.

This was the fall of 2002 and same-sex marriage was legal in 0 of the 50 United States.

Third Time’s a Charm (A brief history of a gay marriage)
Our first marriage Continue reading

Third Time’s a Charm (A brief history of a gay marriage)

Third Time’s a Charm (A brief history of a gay marriage)

Happy Pride from Proudflare, Cloudflare’s LGBTQIA+ employee resource group. We wanted to share some stories from our members this month which highlight both the struggles behind the LGBTQIA+ rights movement and its successes. This first story is from Lesley.

The moment that crystalised the memory of that day…crystal blue afternoon, bright-coloured autumn leaves, borrowed tables, crockery and cutlery, flowers arranged by a cousin, cake baked by a neighbour, music mixed by a friend... our priest/rabbi a close gay friend with neither  yarmulke nor collar. The venue, a backyard kitty-corner at the home my wife grew up in. Love and good wishes in abundance from a community that supports us and our union. And in the middle of all that, my wife… turning to me and smiling, grass stains on the bottom of her long cream wedding dress after abandoning her heels and dancing barefoot in the grass. As usual, a microphone in hand, bringing life and laughter to all with her charismatic quips.

This was the fall of 2002 and same-sex marriage was legal in 0 of the 50 United States.

Third Time’s a Charm (A brief history of a gay marriage)
Our first marriage Continue reading

Community Dispatch: New Hawaii Chapter Says the Internet Still a Force for Good

My first exposure to the Internet Society was back in 1995 when they held the 5th Annual INET International Networking Conference in Honolulu, Hawaii. It was a time when accessing the Internet was a new experience, at least for the public. Terms like hyperlinks, HTTP, FTP, Pine, and the World Wide Web were exciting and the innocence of connecting the world was full of potential.

Fast forward 25 years and the Internet is truly a worldwide resource. With the advent of smartphones, high-speed Internet, wireless technologies, and robust web protocols, accessing and communicating has become a rich experience. But within a quarter of a century, the innocence of the Internet has also tarnished. Not a day goes by without a story in the media about security breaches, privacy lost, horrible things broadcast over social media, online bullying, surveillance, hate speech, and the list goes on.

It is in this environment that we’re launching the Internet Society Hawaii Chapter. The mission of the Internet Society still rings true today: to bring the Internet of opportunity to everyone everywhere, an Internet that is open, globally connected, secure, and trustworthy. These principles apply whether you live in an urban center or rural community. Continue reading

Heavy Networking 456: How To Choose A Higher Ed Program For An IT Career

Today's Heavy Networking explores how to select a higher-ed program for your computer science education, including the key elements of a CS degree, community college vs. 4-year institutions, measuring educational costs and returns, and more. Our guest is Aaron Francis, a systems engineer and instructor.

The post Heavy Networking 456: How To Choose A Higher Ed Program For An IT Career appeared first on Packet Pushers.

BrandPost: Mobile Support: Are Your Employees Getting What They Need?

We’re going to go out on a limb and say most employees bring their own mobile devices to work. You probably do too, and it’s not a bad idea. Using a smartphone or tablet you’re already familiar with – and to which you’re already attached at the hip – often helps you to be more productive as an employee. For companies, embracing the bring-your-own-device trend isn’t a bad idea either. That individual boost in productivity compounds across the enterprise.But that doesn’t mean it’s as easy as turning on the green light and letting employees have at it. Those mobile devices need to be supported – and at a high service level end users have come to expect – or companies risk taking a hit on employee productivity and job satisfaction. You can thank places like Apple’s Genius Bar for raising the bar on support expectations. That’s the same level of first-class support employees expect at work and the standard IT support teams are being held to today.To read this article in full, please click here

BGP Blunder

Another week, another BGP hijack. This time a steel company in western Pennsylvania got surprised with a sizable portion of the Internet’s traffic. In this Network Collective short take, Nick Buraglio joins me to talk about the recent BGP blunder, its causes, some of the reactions, and discuss the BGP optimization tool that sparked the whole issue.

Relevant BGP Security episode with Geoff Houston.

Jordan Martin
Host

The post BGP Blunder appeared first on Network Collective.

Cisco sounds warning on 3 critical security patches for DNA Center

Cisco issued three “critical” security warnings for its DNA Center users – two having a Common Vulnerability Scoring System rating of 9.8 out of 10.The two worst problems involve Cisco Data Center Network Manager (DCNM).  Cisco DNA Center controls access through policies using Software-Defined Access, automatically provision through Cisco DNA Automation, virtualize devices through Cisco Network Functions Virtualization (NFV), and lower security risks through segmentation and Encrypted Traffic Analysis. More about SD-WAN How to buy SD-WAN technology: Key questions to consider when selecting a supplier How to pick an off-site data-backup method SD-Branch: What it is and why you’ll need it What are the options for security SD-WAN? In one advisory Cisco said a vulnerability in the web-based management interface of DCNM could let an attacker obtain a valid session cookie without knowing the administrative user password by sending a specially crafted HTTP request to a specific web servlet that is available on affected devices. The vulnerability is due to improper session management on affected DCNM software.To read this article in full, please click here

Cisco sounds warning on 3 critical security patches for DNA Center

Cisco issued three “critical” security warnings for its DNA Center users – two having a Common Vulnerability Scoring System rating of 9.8 out of 10.The two worst problems involve Cisco Data Center Network Manager (DCNM).  Cisco DNA Center controls access through policies using Software-Defined Access, automatically provision through Cisco DNA Automation, virtualize devices through Cisco Network Functions Virtualization (NFV), and lower security risks through segmentation and Encrypted Traffic Analysis. More about SD-WAN How to buy SD-WAN technology: Key questions to consider when selecting a supplier How to pick an off-site data-backup method SD-Branch: What it is and why you’ll need it What are the options for security SD-WAN? In one advisory Cisco said a vulnerability in the web-based management interface of DCNM could let an attacker obtain a valid session cookie without knowing the administrative user password by sending a specially crafted HTTP request to a specific web servlet that is available on affected devices. The vulnerability is due to improper session management on affected DCNM software.To read this article in full, please click here

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