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HOWTOs and Tutorials Best available technologies overview. First of all, we will discuss how to loadbalance queries from application to our My. Checking Package Authenticity. Upgrading from One Stable Distribution to the Next 6. Recommended Procedure. Step 1 Install OpenSSH package if not installed. Step 2 Create separate group for SFTP users. Below is a list of our current and past job openings. We are executive recruiters for both permanent and contract jobs in Computer, Engineering and Information. E Package Apache2 Has No Installation Candidate' title='E Package Apache2 Has No Installation Candidate' />SQL database cluster. It is nice to have a database cluster that provides high availability and performance, but if you dont find a proper way to connect, your efforts will be useless. Different approaches exist to loadbalance queries from application to the database cluster. The purpose is to loadbalance queries to capitalize available resources but it is not the only one. If a node failed, the requests have to be correctly redirected to the remaining functional one. There are several approaches. PHP 5 ChangeLog Version 5. Date Fixed bug 75055 OutOfBounds Read in timelibmeridian. Fixed bug 72535 arcfour encryption stream. Make sure to read this post before continue Package libapache2modfastcgi has no installation candidate. Install all the required packages. The first approach depends of your application. In my case, the database cluster is dedicated to a Java application, thats why I tried several JDBC drivers to find one that matched my needs. Then we will discuss the My. Runas Run This Program With Restricted Access'>Runas Run This Program With Restricted Access. SQL Proxy. Despite the fact that it is still on alpha release, it looks really promising Finally we will mention the IP layer loadbalancer I detailed in this previous post. In the following section, the goal is to quickly identify the best solutions available to loadbalance queries to a My. SQL cluster. The details are voluntarily not mentioned since the goal of this post is to identify the optimal My. He are all the details to implement WakeOnLAN with a Brocade Router across several subnets. Background information. WakeonLAN WOL has been used for years as a. In this post Im going to guide you through a stepbystep on how to deploy your Sendy installation using AWS ElasticBeanstalk and Docker. Keep in mind that this is. SQL cluster architecture in a context of two nodes. I benchmarked every option according to specific application criteria, but I think the results can be addressed to a more general context. The proposed solutions do not imply any modification from application perspective. JDBC drivers. My. SQLProxy. IP layer loadbalancer. JDBC drivers as loadbalancer. Load Balanced My. SQL driver. I used the ConnectorJ 5. Official JDBC driver for My. SQL in its replication context as explained here. I quickly decided to give it up for several reasons. First of all, the response times were not satisfying, and then this driver does not support too many parallel connections. Finally data integrity was not always assured in stress situations. My. SQL officially suggests this open driver in a replication context. You can find more information about it here. This driver revealed much better performance than the previous one. Unfortunately, in my case, after more than 1. The driver entered in an unstable state where there was no way to connect to the cluster any more. Thats why I had to find an alternative. My. SQLProxy. This tool revealed good performance. Queries were correctly loadbalanced between my two nodes. I simulated the failure of one node the queries were correctly redirected to the remaining one. I didnt notice any inconsistency even for more than 1. The only drawback is that the My. SQL Proxy is still in alpha release and depends of the LUA scripts truthfullnees used to split readwrite queries. However, it was the best candidate so far. Loadbalance queries at IP level keepalivedThis option explained in this previous post is the most mature and as proved to work over years. It allows to loadbalance My. SQL queries between two nodes. We have to define a My. SQL Virtual IP address. The application connects to the cluster through that VIP and then we configure the distribution on a round robin fashion for example. This option handles also the failover. If the node that currently owns the VIP failed, it is automatically taken over by the other at IP layer. Unfortunately, loadbalancing cannot be done at this level to split readwrite queries. It is the best candidate to loadbalance queries and to handle failover, but it is not able to split readwrite queries at this level without modifying the application or adding an extra mechanism that is to say combining it with My. SQL Proxy for example. Now that we have completed our overview of mechanisms distribution, it is time to enter the heart of the matter. Using one of the loadbalancer or a combination of several techniques we will try to list available My. SQL database cluster architecture in a context of two nodes and select the best one according to several criteria such as complexity, ease of administration, performanceMy. SQL Cluster NDB engine. First we will mention the My. SQL Cluster. It is a recent and evolved technology to provide high level cluster architecture composed of three types of nodes. In our limited architecture, this kind of evolved cluster architecture is clearly not adapted since it is intended to a large number of nodes, thats why we will not go deeper in this direction. MasterMaster Replication. Patch Warcraft 3 Frozen Throne. In this scenario, to avoid any modification from application point of view, we set a My. SQL Virtual IP Address VIP using keepalived as explained in this previous post and then configure the distribution so that queries are redirected to one or the other node on a round robin fashion. If a node failed, it is removed from IPVS table and then it does not receive further requests. Thus high availability and performance is assured since total amount of queries is split between the two machines and the global service remains available even if a node failed. Ole Header Structure Corrupt Excel File Repair on this page. Each machine reads the logs of the other and executes the queries of its neighbor that modify insertupdate the database content. The only performance enhancement becomes from the fact that two machines are available to accept read queries. If your application performs much more writes queries, this kind of architecture will not be very efficient. Then you have to be conscious that replication is asynchronous. The content of your two databases is not necessarily the same at a time t. It could be problematic for sensible read queries that should take in account your last write query. Furthermore, the My. SQL community does not promote this architecture. They say it works but they do not advise it. MasterSlave Replication without loadbalancing. This technique is the easiest to deploy, the most mature. I will recommend it although it is not the most efficient one. With a standard masterslave replication we simply add a level of redundancy to a single My. SQL database. To make it work correctly, as with the mastermaster replication, we configure a My. SQL VIP address. Every request is forwarded to the node that currently owns the VIP. In this scenario, the master performs every request, there is no loadbalancing. The slave who reads the master log file replicates the master. In order to facilitate the failover, the read only flag is not set on the slave. Thus if the master failed, the slave will take over the VIP and be able to ensure serviceability without manual intervention. This architecture is safety and easy to deploy. It ensures a level of redundancy in the case of failure without modifying the application. However, if a node failed, we have to repair it manually. MasterSlave Replication with loadbalancing. In this scenario, which is the most complicated to test in our case, the IP loadbalancer can indifferently redirects queries to one or the other backend on a round robin fashion. Then, in order to split read and write queries, we decide to use the My. SQLProxy and the rw splitting. LUA script, since it is the better solution we find to split queries safely. The trick is to configure two VIP master and slave VIP. All write access are forwarded to mastervip and read access to slavevip. At proxy startup, we define a RW backend accessible through the VIP, thus if the master failed, the slave will take over the mastervip and be able to handle write queries since there is currently no way to do it with a LUA script. Current Openings High Tech Professionals. Below is a list of our current and past job openings. We are executive recruiters for both permanent and contract jobs in Computer, Engineering and Information Technology IT in California, Oregon and across the US. The job openings we recruit for include software and hardware engineers, programmers, sales and marketing personnel, human resources, management, quality assurance, testers, technical writers and other jobs in the high tech field. If you submit your resume now, one of our executive recruiters will be able to get in touch with you when a good opportunity arises. We keep all information confidential.