Following on from my Hyper-V Post I thought I would carry on the theme of High Availability and clustered services. Dell's EqualLogic PS Series iSCSI SAN optimise's resources by automating volume and network load balancing. A PS Series Group consists of one or more PS Series Array. Group Members are connected to an IP network and managed as a single system.
iSCSI or internet small computer systems interface to give it its full title, is a block level storage protocol that can be used to create a storage network over Ethernet. iSCSI uses ethernet as a transport medium for data from servers to storage devices or SAN'S (Storage Area Networks) such as EqualLogic. iSCSI encapsulates SCSI commands into TCP/IP and sends these commands over standard Ethernet, because of this iSCSI can be sent over LAN's and WAN's and these Arrays do not have to be located in the same room or even the same Galaxy as your servers.
Snapshots or Checkpoints - One and the Same.
First of all a snapshot is exactly the same as a checkpoint, if you use Hyper-V Manager you will see the term snapshot and if you use System Centre Virtual Machine Manager or SCVMM you will see checkpoint both processes are exactly the same the differences are merely in terminology.
The first and most important thing I would like to cover is that snapshots are not a backup/disaster recovery solution, they are simply a point in time capture of the data,hardware configuration and state of your virtual machine. snapshots are particulary useful for reverting back to a previous state quickly and easily, Microsoft only recommends the use of snapshops in a test/development environment. I only use snapshots for a virtual machine when applying updates to the guest operating system or an application within the OS, if the update is successful then the snapshot is immediately deleted and the VM shutdown so the merge process can take place. I do not recommend keeping snapshots of your Virtual Machines in a production environment.