Hi there! Today I`d like to offer you an article about high availability technologies, provided by VmWare: vMotion, HA and FT. vMotion - the technology allows to transfer VMs from one physical server to another while it`s working (analog of Live Migration in Windows Server Hyper-V R2). Also need to mention that vMotion uses advantages of DRS (Dynamic Resource Scheduler), which allows load balancing.
Storage vMotion - allows transferring VMDK file of VM to another storage device while VM is running.
Difference between these technologies is that first one allows turning off all servers, if VMDK is on shared storage, while the second one – moving VMDK file with VM to another storage, and turning it off.
VmWare HA - this technology scans hosts and VMs for availability all the time. If hosts go down, then VM manager runs them on another physical server. It`s like a hard reboot for VM.
Fault Tolerance - disaster recovery function, which allows creating 24/7/365 running virtual machines. Works as a usual cluster: two identical VMs are running on two physical servers: one node is running in active mode, while second – in passive. All processor`s commands are one side replicated between VMs. Difference between FT and HA is the following: as I said, running VM in first case on another host is equivalent to hard reboot, while in case of FT second node is running from the moment the first node goes down. Need to note that using FT has some limitations: first, both hosts MUST have identical CPUs and second – list of supported CPUs is limited.
That`s all for today. In the next article I`ll tell you how to install and configure all these features. See you!