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SAN/NAS/DAS and VMware

While the technology company I work at has both a EMC CLARiiON CX3 20 and a Dell NAS running Windows 2003 Storage Server, which are rock solid, lately we have been testing a three unit cluster of LeftHand NSM 2060 and some of LeftHand's VSA machines on our ESX cluster.

Most people are probably familiar with the CLARiiON and the Dell NAS but I doubt many have heard of LeftHand Networks. Their NSM 2060 is a rebranded Dell 2950 running a custom Linux distro that they call SanIQ. While it is one of those classic arguments (re: Microsoft/Apple/Linux) where people feel irrationally passionate I personally do not have strong feelings about iSCSI networks versus fibre channel. I prefer iSCSI though because of the reduced complexity and cost in setting it up. (Our CLARiiON is actually connected by iSCSI to our ESX cluster) What excites me about the LeftHand SANs is the ability to leverage iSCSI to slowly build up a SAN.

A SAN from EMC, depending on options, costs in the $100,000 range while an equivalent SAN from LeftHand will cost between $45,000-$75,000. This is accomplished because of the relative cheapness of the hardware and the lack of fibre channel support. The SAN/IQ software allows you the ability to add more units to a cluster on the fly and will automatically restripe and add the additional storage to the pool. Rather than having to completely dump your SAN when need more space this allows you to continue to add machines as you need them.

One of the biggest arguments for fibre channel against iSCSI is the speed advantage it has. This is a very valid argument but one of the neat things about building a SAN with LeftHand or Dell's EqualLogic is that every time you add another machine to the SAN cluster it increases in speed because you are adding more iSCSI ports. After working at a college where money for IT was often non-existent I am always interested in inexpensive solutions. As interesting as LeftHand's NSM appliances are they are still out of the price range for most small businesses/ministries. In a later post I will elaborate on, what I think is much more powerful for them, LeftHand's VSA machines.


ESXi

One of the exciting developments in the VM world is VMware releasing ESXi for free.

ESXi is Vmware's 32 megabyte (yes megabyte) hypervisor that allows bare metal VMs to be run on a server. VMware server, which has been available for a few years as free, is different in that it runs as a process or service on a host system.

There are some pretty important differences that should be noted between the two systems. VMware was able to reduce ESXi to its tiny 32 megabytes because it has had all the management stuff that ESX has eliminated from it. This means that you can not SSH into it like VMware server or ESX 3.5. It also means a lot of ESXi's abilities only come available when you use VirtualCenter. ESXi also has a pretty limited number of servers it can run on. The big advantage over ESXi has over VMware Server is the ability to run many more VMs because of the lack of host OS. You also are able to connect it to iSCSI luns for shared storage and the VM "drives" are SCSI not IDE. One of the reasons why I would opt for ESXi over VMware server is for the simple fact that whenever you update the host operating system you may have to reboot the machine and taking a half dozen VMs off simultaneously. VMware server is more suited though if you are using a lot of appliances or want to be able to use VMware workstation.

For now until I can afford to buy a Foundation pack I will probably be running both types of machines. ESXi for any new machines I am bringing online and VMware server for the rest.