by Joe Gleinser
9. October 2009 17:12
This brief guide will outline the different SAN classes available to the SMB buyer.
Entry Level: If you're buying a SAN, you need a few basic features. iSCSI support and vendor certification (Microsoft, VMware, Citrix) will meet minimal needs. These will enable your virtual environment to utilize high availability features in any of those vendor's environments. HP's MSA 2012i G2 and Dell's MD3000i both meet these criteria. Expect to spend as much as $15k on these devices. The HP will let you mix and match SAS and SATA drives in a single chassis for best use of your SAN dollars. Neither of these solutions offer thin provisioning or clustered storage. What's that mean? Less efficient per GB and much greater risk of failure. If you're concerned about putting all your VMs in one basket, and you should be, then look to the Mid Level, below.
Mid Level: This is what you want, if you can afford it. Two major features enter play here: thin provisioning and clustered storage. I'll touch on both of these now with more to come soon. Thin provisioning allows for oversubscription of storage. Don't worry about it, just do it. Clustered storage is like clustered servers. Two, or more, boxes configured for failover. The HP Lefthand provides the lowest entry cost to true clustered storage. Dell's Equallogic, Compellent, NetApp, Xiotech and others each offer some unique features. Expect to spend at least $30k on this device.
Enterprise: Forget about it. You can't afford it and wouldn't fit in your server closet if you could. Vendors such as HP, EMC, IBM, NetApp and others live here.
Virtual Storage Appliance: For those organizations that may already have a large investment in internal storage in servers or direct attached storage, a VSA may be the best bet. This software solution aggregates storage across your servers into an iSCSI SAN with similiar feature benefits to a full system. You will be able to support High Availabilty and VMotion/Live Migration with this solution. Obviously since you are only buying the software the entry cost is much lower than a hardware solution. HP's Lefthand offers a VSA for VMWare (Xen and Hyper-V are coming). StorMagic has an interesting option that currently supports only VMWare as well, but Hyper-V support is coming.
A not-too-brief market overview should whet your appetite. Look for more info on the features and key differences between vendors to come soon.