Instead, storage admins are having more specific problems: virtual machine management isn't granular enough, some VMs are eating up IOPS and leaving applications prone to latency, and configuring storage is complicated.
That's why Howard Marks, chief scientist at DeepStorage.net, told attendees at his recent virtualization seminar that they need to ask vendors, not whether they integrate with hypervisors but how well they do so.
To evaluate a vendor's ability in this area when you're shopping for VM storage, there are three checklist items you need to be aware of, Marks said:
- VCenter plug-in. Most storage vendors include a vCenter plug-in for VMware environments. But be forewarned, many of these plug-ins don't allow you to see much more than the amount of capacity being used. In more advanced products, however, a vCenter plug-in can let you provision storage, making the creation of data stores far less complicated.
- VAAI or ODX support. The vStorage APIs for Array Integration (VAAI) feature in VMware environments and the Offloaded Data Transfer (ODX) feature in Hyper-V environments allow certain tasks, such as cloning or thin provisioning, to be offloaded from the hypervisor to storage so they can be completed more efficiently. To keep performance up to par, these features have gone from a "nice to have" to a "must-have," Marks said.
- Per-VM visibility. While most VM storage options allow for LUN-specific management, not all of them allow the management of individual VMs. Backup, performance monitoring, cloning -- these can all be done on a much more granular basis, giving the administrator far more control over the VM storage environment.
Keeping these criteria in mind will help you settle on a type of storage. While some analysts might say all-flash is the way to go, Marks warned, a smaller amount of flash might be adequate for some virtual environments. That said, relying on disk in a virtual environment is asking for slow performance. Instead, Marks told his audience a good option might be a hybrid array that employs sub-LUN tiering and flash caching.
To find out more, watch the virtual machine management checklist portion of his seminar above.
What difficulties have you had managing your virtual machine storage?
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