NetBoot/i boots multiple Windows and Linux hosts from iSCSI SANs, and iSCSI target software sanFly is used to turn sever hardware into an IP SAN.
Double-Take is making three updates to sanFly. It's increasing the incremental volume size from less than 1 TB to 2 TB, supporting Microsoft failover clustering and shifting from saving data in a proprietary image format to Microsoft's Virtual Hard Disk (VHD) format. "This makes it easy to attach LUNs to new virtual machines and move them around as well," said Bob Roudebush, director of solutions engineering for Double-Take.
Closer integration with Hyper-V?
Financial services firm Munder Capital Manager uses netBoot/i to boot from an iSCSI SAN while using Compellent Storage Center system's boot from SAN for Fibre Channel boots. Using netBoot/i saves the company from having to buy iSCSI host bus adapters (HBA) for each server to boot from the Storage Center SAN. "NetBoot/i allows us to switch a server from Fibre Channel to iSCSI and back in response to changing performance requirements," said Wolfgang Goerlich, Munder network operations and security manager.
NetBoot/i also allows Munder to shift server workloads to dissimilar hardware for disaster recovery or test/development purposes, saving Munder money on servers. "Before, for disaster recovery, we had to maintain one-to-one duplicate equipment at our secondary site," Goerlich said. With netBoot/i, the company can purchase server hardware at the end of its lease for around $100 to $200, as opposed to spending $6,000 to $10,000 for a production-quality machine.
Finally, netBoot makes physical to virtual conversions in Munder's Hyper-V environment simpler. "The difference between physical and virtual servers is all in the drivers," Goerlich said. "If we can prestage those drivers using disks on the network, we can bring the virtual machine up in a matter of minutes, rather than reading the data out to a virtual hard drive format and updating the drivers." Munder tested this process, and it cut recovery time of a virtual machine from between six and eight hours to less than one hour, Goerlich said.
Goerlich is hoping to see a client-side device or software module that could eliminate the central server netBoot/i needs to deliver boot-from-SAN services to each Hyper-V client on the network. He said that would free up the server used for netBoot/i management and simplify new virtual server installations.
Double-Take's chief technology officer Dave Demlow said the vendor is looking into doing that, especially for Windows 2003 and older operating systems that can't boot directly from an iSCSI LUN. The problem, he said, is that if netBoot/i were to "hard code" a virtual iSCSI HBA association with a particular guest operating system, customers might lose the ability to manage boot images using the central netBoot/i server and to change a physical server's boot image on the fly. But figuring out this issue "is definitely on our list for a variety of reasons," Demlow said.
Potential competition with VMware's VDI
Because netBoot/i allows desktops to store system disks on the network, its use cases could overlap with some instances of VMware's desktop infrastructure (VDI). The difference is that VDI puts all desktop operations, down to mouse and keyboard inputs, on the ESX server while netBoot/i only abstracts the system disk, Roudebush said.
"That one aspect of what they're doing sounds like VDI, but it doesn't require a connection broker or any type of virtualization -- it's still a thick client, but just boots off the SAN," said Enterprise Strategy Group analyst Lauren Whitehouse. If customers don't want to go the VDI route, this method of centralizing desktop storage resources might be a little less complex, she said.