Categorie: Linux

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 ...


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 ha2 server02 [/code] Installation We will install pacemaker, it should install corosync as ...


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 ...


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 ...


Configure multipath FC on Debian (HP EVA, Brocade dual 8GB FC)

This detailed how to guides to high availability and performance on Debian/Ubuntu for with a dual FC HBA (Brocade) and shared storage on a HP EVA6300.  Tested on Debian Linux 5.x and 6.x bits running on HP Proliant Dl360 and DL380 models, with 8GB FC Host Bus Adapters from Brocade. Configure the software we need ...


MySQL – Master/Master replication on Windows

Here you will find the step-by-step actions to succesully setup a master/master replication cluster of two MySQL 5.5 nodes on Windows. Prerequisites – Two servers with Windows installed (make sure all updates are installed) – Both machines have a clean install of MySQL 5.5 – Firewall is configured to allow port 3306 – Check the ...


No space left on device – running out of Inodes

One of our development servers went down this weekend. Problems started with a small PHP script that claimed that claimed “No space left on device”. Nagios however reported 32% usage of space, so that couldn’t be it? If you ever run into such trouble – most likely you have too many small or 0-sized files ...


Two way authentication for SSH

On each linux server that you install there will be SSH to login as root and install/edit software. Even if you secure this, by disallowing the root user to login, there is a chance somebody might figure this out and use brute-force to hack in to your system. In may situations i have added firewall ...


Suse – Zypper download only option

On Suse there are both Yast and Zypper but sometimes i need the option to download source packages to customize them for install. [code]zypper -l -y update –download-only[/code]


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] ...