OCZ NVMe z-Drives: A Review
I'm bullish on NVMe solid state drives in the virtualized datacenter. Previously I gave a brief overview on NVMe technology and why I think it will radically change the virtual datacenter. More and more companies are offering NVMe drives, and OCZ, a Toshiba company, has just announced its latest NVMe drive: the Z-Drive 6000. These drives come in 800GB, 1.6TB and 3.2TB models, with a huge 8TB model scheduled to come out in the first half of 2016. The price of these upcoming models has not yet been announced, but they're expected to be competitive with other enterprise-class NVMe drives.
What Is NVMe?
For those unfamiliar with NVMe, a quick introduction is in order. NVMe (standing for Non-Volatile Memory Express) is a standard interface for PCI express to access SSD drives. SAS/SATA interfaces were designed decades ago for spinning disks; they did an outstanding job in this context, but were at best a mediocre interface for SSD drives.
The NVMe interface, on the other hand, was designed from the ground up for use with flash. The NVMe protocol is lightweight, fast, and designed to accommodate many command queues and huge (64K) queue depths. An added benefit of NVMe drives is that they actually decrease the CPU load by using only two CPU cycles per IO, rather than the five it takes with SATA devices.
OCZ memory and SSD drives have long been a favorite of high-end consumers and those in the gamer community, but they also have a presence in the datacenter with their Intrepid SSD drives. With the introduction of the Z-Drive 6000, OCZ should continue to make inroads into the datacenter.
OCZ’s Z-Drive 6000 is a 2.5" NVMe drive that connects to the PCIe bus via a U.2 connector. OCZ is touting this as a top-of-the-line storage drive, and rightly so as its performance numbers are as impressive as any that we have seen for this type of device. The Z-Drive 6000 delivers 700,000 random 4K reads and 160,000 random 4K writes, and 2,900 and 1,900 MB/s sequential reads and writes, respectively. The latency numbers are equally as impressive; 80 and 20 nanoseconds for reads/writes. These performance numbers put the Z-Drive 6000 in the same class as other datacenter NVMe drives like the HGST SN100, Intel DC P3700 and Samsung XS1715.
By using the 2.5" drive form factor with a U.2 connector, the Z-Drive 6000 can be hot swapped out like SATA SSD drives. I expect to see more and more companies go to 2.5" form factor in the future. The device has a five-year warranty, and is rated at 1 drive write per day (DWPD). Data will be kept alive for one year on the device if it's removed from the power source.
OCZ is showing full support for all major hypervisor platforms, with NVMe drivers available for Windows Server 2012, Linux and VMware ESXi. The Z-Drive 6000 is already on the VMware HCL for ESX 5.x and 6.x. It's expected that many server builders will begin to offer them on their systems.
What does this mean for the virtualized datacenter? I see the Z-Drive 6000 as being a great boon to not only hyperconverged servers, but also to storage arrays. Servers that use SSD devices with a traditional SATA interface are only able leverage a single command queue that operates at a depth of up to 32 (AHCI) or 254 (SCSI), while NVMe drives support 64K queues and 64K commands.
Because of the IO blender effect of virtual environments, the impact of the increased queue depth will be substantial. But an even bigger advantage of NVMe drives is the low latency and large bandwidth they have. Currently, most servers that run a hypervisor have excess cycles due to waiting on storage, but NVMe devices will be able to decrease the amount of time these servers are waiting on data from storage. This allows virtualized servers to more fully utilize their CPU.
Help for the Hyperconverged
NVMe drives will also help hyperconverged systems; for example, VMware has reported that by leveraging NVMe drives in a 32 node VSAN cluster, it was able to achieve 3.2M IOPS. Likewise, storage -- especially arrays based on x86 architecture -- should see a huge performance gain once NVMe drives are implemented.
It looks like OSZ has released a top-of-the-line NVMe drive comparable to the best in the field that should make datacenters more efficient.
Tom Fenton works in VMware's Education department as a Senior Course Developer. He has a wealth of hands-on IT experience gained over the past 20 years in a variety of technologies, with the past 10 years focused on virtualization and storage. Before re-joining VMware, Tom was a Senior Validation Engineer with The Taneja Group, were he headed their Validation Service Lab and was instrumental in starting up its vSphere Virtual Volumes practice. He's on Twitter @vDoppler.