Today we introduce our premium Geo Cluster 4XL service, our own technical solution for a geographic server High-Availability cluster that will ensure even higher contractual availability (SLA) for your internet projects than our standard hosted services allow. What is an HA Geographic Cluster? 
A High-Availability cluster (also known as a Failover cluster) uses two (or more) servers to ensure continuous provision of hosted services. When the primary server fails, it is automatically replaced through replication by a second server with the same configuration, which is operated in a different datacenter for higher security (hence geographic). How Does Our Geo Cluster Server Work? The geographic failover server cluster basically contains two Dell Power Edge servers (node 1 and node 2 in the diagram). The first server (primary) provides services in normal mode. The second (failover) server is always on standby in the second datacenter, ready for situations when the primary system fails. The primary server is automatically monitored (every few seconds). If monitoring detects an error (either SW or HW) in the active system (server 1), the second node (server 2) takes over. When is a server cluster used? It is used in situations where we need to ensure that if one node fails, another node takes over the IP address of the original and starts handling requests as soon as possible. The Geo cluster server shares only one IP address. - Only one node has the given IP address at any time, which is designated as master. Other nodes (node 2) are backup reserves (there can be multiple servers, but only one is included in the basic offer). - If one node is preferred, the others serve only as backup in case the master fails. After the master node fault is resolved, this node takes over the IP address again. The solution is therefore ideal for all organizations that need to ensure business continuity and maximum uptime without a single point of failure. 2nd Generation Cluster Technical Solution 
The cluster solution is worthwhile for internet projects with high sensitivity to availability. Geo cluster 4XL basically consists of two Dell Power Edge servers with parameters: 2 x Intel Xeon Quad Core, 2 x 3 TB HDD SATA (SAS also available), 16 GB ECC RAM (up to 96 GB RAM), Linux and Windows operating systems, and unlimited data connection from 2 x 1 Gbps. The price of the basic dedicated cluster designated D-Geo Cluster 4XL is 6999 CZK excl. VAT (249 EUR), the managed variant designated M-Geo Cluster 4XL including subsequent virtualization, virtualization API and administration costs the customer 8199 CZK excl. VAT (304 EUR). The high SLA value of 99.96% is contractually guaranteed. "After more than half a year of testing, we decided to expand our commercial offer with high-availability services and a contractual guarantee of 99.96%, which we offer both in dedicated and managed variants, meaning not only with a guarantee of high availability but also with customer administration," says Zdeněk Maršál, Sales Director of Greendata, which operates the Greenhousing service. "We can subsequently virtualize the server cluster for customers, enabling them, for example, to host premium web services," adds Maršál. The prices listed are excl. VAT. Services are covered by a 30-day Money Back Guarantee. Geo clusters are becoming very popular as a tool for implementing and operating "immortal" applications and services. ed