The missing piece of the virtualization puzzle

If storage is the last thing you consider in a virtualization deployment, it could be the first thing to go wrong

I recently reviewed Scalent's V/OE, or Virtual Operating Environment, which is software that automates the provisioning of both storage and networking for server operating system images and virtual machines. V/OE also automatically deploys images of any guest OS to a VMware partition.

The result is an essentially liquid datacenter, in which server images are completely portable. You could move a server OS from a physical machine to a virtual machine, or from one virtual machine to another, and even back to a physical machine, all without ever having to copy files or change any settings manually. Each server needs to have a lightweight agent installed, but this has minimal impact on the system.

The Scalent system automatically changes the VLAN settings on the appropriate switch, the network settings on the server instance, the LUN masking and other storage settings, the VMware partitioning, and the virtual name of the HBA for the server instance.

[ See Logan Harbaugh's review of Scalent V/OE and other high-availability and disaster recovery solutions for virtualization environments, including DataCore SANmelody, Marathon Technologies' everRun VM, Stratus Technologies' Avance, and Vizioncore vRanger Pro. ]

Because storage replication features can be used to keep the boot-from-SAN images up to date in a backup datacenter, switchover time is very quick, limited to the time it takes the OS to boot from the new SAN image in the new location. This is typically faster than booting from a local disk.

The level of flexibility that Scalent offers, in terms of being able to run an OS instance either on hardware or virtual machine, is remarkable -- and especially useful in disaster recovery. Often with other failover systems, the two servers need to be identical to ensure that VMware drivers for CPU type, motherboard type, VMware partitioning, network settings, and capacity all match between the two. With Scalent, the backup server doesn't have to match the original.

Partnerships between storage vendors (such as NetApp, EMC, DataCore, FalconStor, and 3Par) and virtualization vendors (VMware, Citrix, Parallels, and Microsoft) promise similarly easy provisioning of guest OS images and storage. Other storage vendors are integrating backup and disaster recovery tools with VMware and other virtualization platforms to automate backups of VMDK files and the equivalents for other virtualization platforms.

These partnerships signify not only that virtualization has become a checkbox for many sales calls, but also that more critical applications are being virtualized. An increasing number of virtualization customers are feeling the need for rapid provisioning and disaster recovery and backup options.

VMware has announced that storage resource management capabilities will be included in its forthcoming Virtual Datacenter OS, due next year. VDC-OS will enable on-demand provisioning of storage in addition to memory and CPU resources. It will also support thin provisioning of VMFS volumes, which won't use the full size of a partition if there is nothing installed in it.

Nearly all of the major storage vendors have announced partnerships with one or more of the virtualization vendors. These partnerships can be a wonderful thing, but only if your storage vendor happens to have a deal with your virtualization vendor. The sooner these partnerships are no longer necessary, the better for customers. But to get to where any storage will work with any virtualization platform, a Storage Networking Industry Alliance standard will be necessary.

It’s not just the VM disk format -- it’s how the virtualization software communicates with the storage management piece to provision additional partitions. It’s a pretty complex set of specs, which is why it’ll probably take the storage and virtualization vendors years to hammer it all out, assuming they ever do. In the meantime, you'll need to keep an eye on the alliances and proceed carefully.


Copyright © 2008 IDG Communications, Inc.