A redundant array of independent/inexpensive disks (RAID) allows high level of storage reliability and overall performance for your system. RAID allows combining multiple disks to form a single logical unit. There are several different levels of RAID available, like RAID 1- which requires two identical drives, RAID 5- which requires 3 identical drives and RAID 10- which requires 4 identical drives, depending on the needs of your system. RAID provides real time replication of data onto the secondary hard disk. This means that, in case of dedicated servers, if the server goes down for reasons like corrupt databases, injections, human errors; primary disk fails, the data will not be lost and can be fetched from the secondary drive.
RAID is however not to be confused with Server Mirroring and Failover Redundancy Solution or Cloud Server Architecture.
Server Mirroring and Redundancy solution setups consist of two identical Linux servers. One acts as the Master and other as Slave Server. The setup of server mirroring solution is such that there is a real time data replication from Master to Slave Server, known as Server Mirroring.
If, for any reason, the Master server fails, all the hosted domain and applications start resolving from Slave Server without any downtime known a Failover redundancy. Thus, Server Mirroring and Failover Redundancy Solution offer 100% server uptime.
Cloud VMs architecture consists of clustered setup of high specification dedicated servers and network attached storage devices (also known as Private Cloud), offering 100% uptime guarantee. Cloud hosting VMs are known for High Availability, Fault Tolerance, Scalability and Reliability.
High availability refers to the VM being available without any downtime.
Fault Tolerance means that the VM should continue to operate even if some of its components fail, without complete breakdown. Scalability is the capability to add individual resources to the VM in case there is surge in demand. Reliability, the VM should be able to perform its required/stated functions.