Problems of replicating Virtual Machine

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Spread the love          One of the biggest advantages of VMs, is the capability of cloning and replicating them. This allows the creation of a number of similar systems, without having to replicate the configuration and installation time. Unfortunately , there are a small number of downsides: The MAC addresses are also cloned. Remember to generate new MAC addresses on each new cloned VM. Also, Ubunto caches this value, which will generate a typical error message on dmesg: “udev: renamed network interface eth0 to eth1” . To avoid this problem, delete the the file /etc/udev/rules.d/70-persistent-net.rules and restart the system.

How to manage a small Virtual Machine infrastructure

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Spread the love          Over the last months, I felt the need to start a small virtual machine infrastructure to manage every small need on a laboratory at work. The set up infrastructure is the following: 1x Apple Macbook Pro 4.1 – for development of the appliances 2x HP DL360 with 8GB RAM running Ubuntu 10.4 – to run the VMs Note that is this NOT a production environment. This only covers a LAB needs and requirements, so stuff like redundancy and fail safe will not be included.   Over the next few weeks, I’ll add some important notes.   Workflow The workflow is quite strait forward: set up the VM on the Macbook running Oracle Virtual Box; Deploy the VM on the HP server running Linux KVM To go from one step to the other, conversion between formats is required. We’ll cover that later.

Generating random files

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Spread the love          Why on earth would someone want to generate files of random content (not files with random name) ? Well, there is one big reason to do it: generate incompressible files. This seems a small reason, but there are a number os usage scenarios (apart from proving that random content is incompressible), most focus on transmitting files. Although is transparent to most people, but some tools do background compression namely, https, IPSEC and SSL VPNs, etc, and as such, trying to measure real world performance on those require incompressible content. First, how to generate it (assuming you can talk *NIX) ? dd if=/dev/urandom of=random.file bs=1m count=100 Where: if – Input file, in this case the virtual file /dev/urandom of – Output file, the name of the destination file bs – Block Size, the default block size for dd is 512bytes, which makes sense when copying files, but not terribly useful when creating files with a determined size. In this case 1MB count – number of blocks to be copied In this case, I needed to create a 100MB file of random content. The result: > dd if=/dev/urandom of=random.file bs=1m count=100 100+0 records in 100+0 records out 104857600 bytes transferred …