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Recently, I have been asked to find a way how to clone Linux machines running in a remote virtual lab. The machines have single disks, they all are accessible over SSH and configured with the same login credentials. The goal is to make identical copies of their disks, download the disks and rebuild machines locally in the virtual lab.
On Linux based systems, utility 'dd' is very often used to make identical copy of a disk. I have used this command together with 'ssh' and 'gzip' commands to copy and compress remote disks and send them on the fly to a local disk over SSH connection. For instance, the command below issued on a local machine copies a disk /dev/sda of a remote Linux machine with IP address 10.10.10.11 to a local disk:
$ ssh [email protected] "/bin/dd if=/dev/sda | gzip -c" | dd of=disk.raw.gz
Explanation:
/dev/sda - disk located on remote machine
disk.raw.gz - gzip compressed copy of disk /dev/sda on local machine
gzip -c - send compressed file to stdout
I wrote a BASH script backup-images-1.0.sh that automates process of cloning disks of remote Linux machines. The script reads IP addresses from Continue reading
Be honest. How many of you are still logging directly into the systems that you administer, via SSH, and changing things? I am. It’s a hard habit to break, but it’s one worth breaking. Luckily I don’t have very many servers of my own to manage, but changing things manually, instead of modeling those things in a language of automation is a sure way to build up technical debt and regret it later.
It’s been a long time since I’ve done any sort of system administration as my day job. But I talk to Ansible customers on a daily basis, and I have seen all sorts of environments: simple, complicated, small, large, well-managed, and poorly-managed. But one constant that I see throughout is increasing complexity and scale. Even for small shops with a few users, today’s platforms for data management, cloud hosting, and containers require a lot more distinct machines under management for their operation than the good old days when a couple of bare-metal LAMP servers could run a full web application.
Many people have written about the exponential growth in computing: from the early days of mainframes hosting hundreds of users and applications, to a single server rack Continue reading
Marcelo Manjon
The spate of high profile cyberattacks have raised the awareness of cybersecurity to the board level and encouraged venture capitalists to pour money into this sector. In 2013 the industry received $1.7 billion of VC money across 240 deals, hitting a five-year high in both funding and number of deals, according to CB Insights. Today the cybersecurity landscape is comprised of nearly 500 companies, CB Insights says.
But many of these security tools are fragmented, and as a result it is often difficult to describe, categorize and compare various security tools given the numerous subcategories and new startups tackling one small part of the problem. In order to better understand this complex market and put into perspective the various solutions constantly coming to market, I would like to propose a framework we use at XSeed Capital to parse the market.
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There are 20 relatively easy MPLS questions in the below MPLS QUIZ. It should take around 30 to 45 minutes and above 50 is nice score in my opinion. Although this post is related with MPLS, you can click here for the other tests. Please specify your name and email address to receive an email for… Read More »
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I have a T-shirt from the nice folks at NetBeez, and on the back it says “Ask me about my Beez!” Naturally people can’t resist asking and I’ll happily explain, but on the off chance that you’re not lucky enough to be standing behind me I’m going to share my thoughts on NetBeez and the product sample they were kind enough to let me play with.
I met NetBeez at Networking Field Day 9 where they presented their distributed monitoring solution. I’m not going to repeat what they said for the most part, so if you have time, it’s worth watching their full presentations from the NetBeez page at Tech Field Day.
The high level overview of the NetBeez solution is that they offer small, cheap, plug-and-play network agents that you can put on your network, from where they will perform connectivity and performance tests and report back to a central dashboard which can generate reports, statistics and alerts. The agents are designed to be cheap enough that you could put one on every remote site and monitor, say, access to a critical corporate server and find out quickly which remote sites are seeing Continue reading
Cisco’s current network programmability certs uses two exams per cert, with the second exam focusing on ACI. That represents the first ACI-focused specialist exams from Cisco, and a great reason to learn about ACI and validate that knowledge. Today’s post looks at the ACI-focused exam for the Cisco CNPES Cert exam: the 600-512 NPENGACI exam. We’ll look at both the exam and a related video course.
Other posts in this series:
First, to set the stage, Cisco rolled out their network programmability (read: SDN) certifications over a period of months, mostly in 2014. Figure 1 shows these four certs, with the engineering specialist cert focusing on engineering and implementation.
Today’s post focuses on the second exam: the 600-512 NPENGACI exam. The name itself is a bit of a mouthful:
Network Programmability ENGineering with ACI
Basically, the NPENG 600-504 exam covers SDN implementation excluding ACI, NPENGACI 600-512 exam includes ACI.
This list provides the links for more details – for the certification, each of the two exams, and each of Cisco’s two Continue reading
Packet Pushers podcast is a constant source of inspiration for my blog posts. Recently I stumbled upon Rob Sherwood’s explanation of how they package Big Cloud Fabric:
It’s a vertically integrated solution, from Switch Light OS to our SDN controller and Big Cloud Fabric application.
Really? What happened to openness and disaggregation?
Read more ...