Bookmarks for 28 ago 2014 from 09:32 to 11:55

These are my links for 28 ago 2014 from 09:32 to 11:55:

  • Keepalived for Linux – Keepalived is a routing software written in C. The main goal of this project is to provide simple and robust facilities for loadbalancing and high-availability to Linux system and Linux based infrastructures. Loadbalancing framework relies on well-known and widely used Linux Virtual Server (IPVS) kernel module providing Layer4 loadbalancing. Keepalived implements a set of checkers to dynamically and adaptively maintain and manage loadbalanced server pool according their health. On the other hand high-availability is achieved by VRRP protocol. VRRP is a fundamental brick for router failover. In addition, Keepalived implements a set of hooks to the VRRP finite state machine providing low-level and high-speed protocol interactions. Keepalived frameworks can be used independently or all together to provide resilient infrastructures.
  • The BIRD Internet Routing Daemon Project – BIRD is an Internet Routing Daemon designed to avoid all of these shortcomings, to support all the routing technology used in the today's Internet or planned to be used in near future and to have a clean extensible architecture allowing new routing protocols to be incorporated easily. Among other features, BIRD supports: * both IPv4 and IPv6 protocols * multiple routing tables * the Border Gateway Protocol (BGPv4) * the Routing Information Protocol (RIPv2) * the Open Shortest Path First protocol (OSPFv2, OSPFv3) * the Router Advertisements for IPv6 hosts a virtual protocol for exchange of routes between different routing tables on a single host a command-line interface allowing on-line control and inspection of status of the daemon soft reconfiguration[...]
  • How to make MaxScale High Available with Corosync/Pacemaker | MariaDB – MaxScale, an open-source database-centric router for MySQL and MariaDB makes High Availability possible by hiding the complexity of backends and masking failures. MaxScale itself however is a single application running in a Linux box between the client application and the databases – so how do we make MaxScale High Available? This blog post shows how to quickly setup a Pacemaker/Corosync environment and configure MaxScale as a managed cluster resource.

Bookmarks for 26 ago 2014 through 27 ago 2014

These are my links for 26 ago 2014 through 27 ago 2014:

  • Regular Expressions – Regular expressions ("regexes") are supercharged Find/Replace string operations. Regular expressions are used when editing text in a text editor, to: check whether the text contains a certain pattern find those pattern matches, if there are any pull information (i.e. substrings) out of the text make modifications to the text. As well as text editors, almost every high-level programming language includes support for regular expressions. In this context "the text" is just a string variable, but the operations available are the same. Some programming languages (Perl, JavaScript) even provide dedicated syntax for regular expression operations.
  • MySQL active-passive cluster | Your IT goes Linux – We will use the iSCSI Lun defined in our iSCSI cluster as a shared storage and we will run MySQL in active-passive (fail-over) mode using Pacemaker and Corosync cluster engine. The cluster will have to connect to the iSCSI target, mount the iSCSI partition on one node and start a MySQL service which has all its data on this partition.
  • Perl – [...] Perl has horrors, but it also has some great redeeming features. In this respect it is like every other programming language ever created. This document is intended to be informative, not evangelical. It is aimed at people who, like me: dislike the official Perl documentation at http://perl.org/ for being intensely technical and giving far too much space to very unusual edge cases learn new programming languages most quickly by "axiom and example" wish Larry Wall would get to the point already know how to program in general terms don't care about Perl beyond what's necessary to get the job done. This document is intended to be as short as possible, but no shorter[...]
  • Linux Performance – This page links to various Linux performance material I've created, including the tools maps on the right, which show: Linux observability tools, Linux benchmarking tools, Linux tuning tools, and Linux observability sar. For more diagrams, see my slide decks below.
  • AIXchange: Useful Storage Links – Here's an assortment of really good storage-related articles — the majority of which are found on IBM developerWorks — that are worth your time. While some of them are a few years old, they still provide relevant information.

Bookmarks for 28 mar 2014 through 29 mar 2014

These are my links for 28 mar 2014 through 29 mar 2014:

  • LDAP org chart | bitcube.co.uk – For centralised authentication and authorisation, LDAP is the de-facto standard. Whether in its pure form on Unix or in Active Directory guise on Windows, everyone uses it. What many people don't realise is that you can store all sorts of useful (and not so useful) information in LDAP. One field which can be useful is the "manager" attribute. One of our customers use that and so we've written a small script to graph it using the excellent Graphviz tool. It will probably need customising for specific cases, however we hope that people find it useful nonetheless. If you want to alter the output, do have a look at the record format documentation.
  • Puppet errors explained | bitcube.co.uk – Puppet is a wonderful system automation tool, however the learning curve can be a little steep. We've collected some of the errors messages and "strange" behaviour you may come across together with explanations to help overcome these hurdles and boost adoption of this fabulous tool. If you have any useful errors and explanations, please do send them in and we'll update this article.
  • SCAP: Guide To The Secure Configuration of Red Hat Enterprise Linux 5 – This guide has been created to assist IT professionals, in effectively securing systems with Red Hat Enterprise Linux 5.
  • DNS Load Balancing and Using Multiple Load Balancers in the Cloud – [...] Load balancing in general is a complicated process, but there's some secret sauce in managing DNS along with multiple load balancers in the cloud. It requires that you draw from a few different sets of networking and “cloudy” concepts. In this second article in my best practices series (my first post covered how to use credentials within RightScale for storing sensitive or frequently used values), I'll explain how to set up load balancers to build a fault-tolerant, highly available web application in the cloud. Here's what you’ll need: Multiple A records for a host name in the DNS service of your choice Multiple load balancers to protect against failure [...]
  • gdnsd – gdnsd is an Authoritative-only DNS server which does geographic (or other sorts of) balancing, redirection, weighting, and service-state-conscious failover at the DNS layer. gdnsd is written in C using libev and pthreads with a focus on high performance, low latency service. It does not offer any form of caching or recursive service, and notably does not support DNSSEC. There's a strong focus on making the code efficient, lean, and resilient. The code has a decent regression testsuite with full branch coverage on the core packet parsing and generation code, and some scripted QA tools for e.g. valgrind validation, clang-analyzer, etc. The geographically-aware features also support the emerging EDNS Client Subnet draft for receiving more-precise network location information from intermediate shared caches.

Bookmarks for 25 mar 2014 through 28 mar 2014

These are my links for 25 mar 2014 through 28 mar 2014:

  • blblack/gdnsd – gdnsd is an Authoritative-only DNS server. The initial g stands for Geographic, as gdnsd offers a plugin system for geographic (or other sorts of) balancing, redirection, and service-state-conscious failover. The plugin system can also do things like weighted address/cname records. If you don't care about these features you can ignore them :).
  • How to Create and Apply Patches in GIT using diff and apply Command – Creating a patch in GIT is a great way to share changes that you are not yet ready to push to a public branch of a project.
  • Your own Dynamic DNS in 3 steps | The Nexus – This is a "niche" post: it will really only appeal to you if you have access to your own — or a friend's — name servers and want to use your own domain to track your dynamic IP addresses, such as your home router's. You will still have to buy your own domain, cheap if you go to internet.bs or namecheap.com. I hear that the latter even provide their own dynamic DNS service although I cannot tell you anything about its quality/flexibility. So, why this post? It's for you, my friends, budding entrepreneurs who wish to bootstrap your business and know that every cent counts. Maybe you feel that you could host your product's web site on a home computer. Maybe you need more control over what happens on that server. Or maybe you want to be able to log on to your development machine from anywhere in the world. Whatever your reasons, you're still here. So let's get started.
  • Apache – Prefork or Worker | Code Bucket – Apache is the most common and famous webserver. Everyone knows about apache and most of us also have hands on experience with apache. But few of us know that apcahe2 comes with 2 multi processing modules(MPMs): 1. Prefork 2. Worker
  • Ottimizzazione di Apache, dall’analisi ai parametri – [...] I recenti sviluppi nel campo della virtualizzazione hanno accelerato la moltiplicazione di ambienti virtuali vps a basso costo, molto convenienti ma a volte carenti dal punto di vista delle risorse di sistema. Molto spesso questi ambienti vengono utilizzati a scopo di testing o come ambienti di produzione all'interno dei quali viene implementato l'utilizzo di un web server. Apache, come ben sappiamo ,e uno dei web server piu diffusi e nella maggioranza dei casi rappresenta la scelta di default su un grandissimo numero di installazioni [...]