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Categorie: Networking

Ceph – full blown NVMe cluster

Ceph is open source software designed to provide highly scalable object-, block- and file-based storage under a unified system. Ceph storage clusters are designed to run on commodity hardware, using an algorithm called CRUSH (Controlled Replication Under Scalable Hashing) to ensure data is evenly distributed across the cluster and that all cluster nodes can retrieve ...

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Pacemaker and Corosync HA

In this setup we will setup a HA failover solution using Corosync and Pacemake, in a Active/Passive setup. Installation and Setup Prerequisites Hosts or DNS resolvers NTP Must be installed and configured on all nodes [code]cat /etc/hosts 10.0.1 10 ha1 server01 10.0.1.11 ha2 server02 [/code] Installation We will install pacemaker, it should install corosync as ...

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CGN: Carrier-grade NAT

Every network engineer with some experience knows RFC1918 address space from the top of their head. So no need to explain that almost every office, home user and some datacenter networks are using IP’s from this RFC. So far, so good. But, what if you have a large network with more then 10 physical locations ...

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Ceph TCP Performance Tuning Ubuntu

Below are a few TCP tunables that I ran into when looking into TCP performance tuning for CEPH based on our 10Gbit configuration. [code]# 10GE/32MB (33554432) #net.core.rmem_max = 33554432 #net.core.wmem_max = 33554432 #net.core.rmem_default = 33554432 #net.core.wmem_default = 33554432 #net.core.optmem_max = 40960 #net.ipv4.tcp_rmem = 4096 87380 33554432 #net.ipv4.tcp_wmem = 4096 65536 33554432 # 10GB/54MB (56623104) net.core.rmem_max ...

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Ubuntu Bonding with LACP

Linux allows us to bond multiple network interfaces into single interface using a special kernel module named bonding. The Linux bonding driver provides a method for combining multiple network interfaces into a single logical “bonded” interface. [code]sudo apt-get install ifenslave-2.6[/code] Now, we have to make sure that the correct kernel module bonding is present, and ...

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Configuration of HP IRF (Intelligent Resilient Framework)

HP’s Intelligent Resilient Framework (IRF) is an advanced technology that allows one to virtualize 2 or more switches into a single switching and routing system also known as a “virtual switch”. IRF is available on the new HP A series switches such as the A5120 model and the A5500-5800 models. From Wikipedia: Intelligent Resilient Framework ...

IPv4 versus IPv6 – Linux

All of my servers are running on both ipv4 and ipv6 for a few years now, however i had never checked to see if people were actually connecting over IPv6 to our network yet. I know i do, since i am using the Tunnelbroker from HE.net. More information on that can be found here. In ...

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Cloud Computing – Mind your WAN connection!

The last couple of years i’ve been involved in some projects regarding Cloud Computing and had to face with performance issues at some of these clients. The situations were almost identical; – Customer switched from client-server to Cloud Computing (Citrix or something similar) – Existing internet configuration is used and/or extended – All application- and ...

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Cisco IOS – Enabling netflow

I’ve  been using Netflow to monitor network traffic since beginning of this year and still i’m a big fan. Netflow allowes you to really dig in the actual network traffic that is generated by servers (or services) and let’s you investigate traffic that should be blocked. Configuring a Cisco to export netflow statistics to a ...

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NFDump – Librrd issues

I’ve had a lot of issues when installing NFDump on a new Wheezy (Debian) system. I solved it after hours of pain. The error i had: [code]configure: error: Can not link librrd. Please specify –with-rrdpath=.. or[/code] So i added the path to my lib folder and got: [code]configure: error: C preprocessor “/lib/cpp” fails sanity check[/coe] ...