VMware ESXi
After running full fledged VMware ESX v2 and 3 clusters, I have moved on to testing ESX3i. Even though it is free and does not provide HA(High Availability) or DRS (Distributed Resource Scheduler), it is a great option for a disaster recovery site or emergency server. HA, DRS, and other licensed features can be utilized with ESXi if you have a Virtual Infrastructure Server and the appropriate licenses bought from VMware. Most server manufactures can ship with ESX3i directly from the warehouse. These servers are typically diskless and ESX is loaded from an internal solid state device. The only problem I have with this is that the solid state device in normally a flash interface or USB drive. Problems that are inherent with flash drives could possibly show in these implementations, mainly write wearing. The setup is extremely easy from USB disk, boot from it, configure the IP, create a password for the system and you are off and running. I prefer to do the install of ESXi to local disks (raid 1) for redundancy purposes. Even though this is a free version, it does support ISCSI and FIber SAN connectivity. This makes it great for an emergency VM node to add to a cluster whos data store is on a fiber or ISCSI lun. Just remove the failed VM server from the cluster to free up its license, then add the ESXi server through the Virtual Infrastructure server. Once in, you can allocate the removed VM HA and DRS licenses to the new machine and start migrating virtual machines over!
ESXi Differnces
You do loose HA and DRS if you do not have a license and license server (Virtual Infrastructure). Another thing that is gone is the service console. This is a good thing in my opinion. It decreases the number of patches required and also makes the system more secure. The whole less is more in security seems to work here. No remote SSH or command line access eliminates some risks. There is a remote console system that can be loaded as a virtual machine to allow console functionality to the ESXi server. Another good option is the “lockdown mode”. Enabling this disables remote console command line access from the servers. The only way to access the console in this mode is via an out-of-band management interface, like IBM RSA (Remote Supervisor Agent) or HP ILO (Integrated Lights Out) management cards.
From VMWare website:
- 4-Way Virtual SMP. Enable a single virtual machine to use up to four physical processors simultaneously. VMware ESXi extends this unique feature from two to four processors. With 4-way Virtual SMP even the most processor intensive software applications like databases and messaging servers can be virtualized.
- 64GB RAM for virtual machines. Run the most memory-intensive workloads in virtual machines with a memory limit extended to 64GB.
- Support for powerful physical server systems. Take advantage of very large server systems with up to 32 logical CPUs and 256GB RAM for large scale server consolidation and DR projects.
- Support for up to 128 powered-on virtual machines. Take advantage of very large server systems for enterprise-class server consolidation and containment with support for up to 128 powered powered on virtual machines on a single server.
- Flexible virtual switches. Scale up to handle more virtual machines. Virtual switches can be created with any number of ports from 8 to 1016, and up to 248 virtual switches are supported per host.
