As desktop SSDs bump into the limits of the 6Gbps Serial ATA interface, server-oriented drives are enjoying the spoils of PCI Express connectivity. OCZ's latest Z-Drive 4500 has a eight-lane PCIe 2.0 interface that allows it to hit a claimed 2,900MB/s with sequential reads and 2,200MB/s with writes. The drive is also rated for up to 252,000 IOps with 4KB random reads and 78,000 IOps with random writes. Yowza.
Like its Z-Drive R4 predecessor, the 4500 Series uses OCZ's Virtualized Controller Architecture (VCA) to combine eight onboard SSDs based on current-gen SandForce silicon. This VCA mojo runs on a separate chip and presents the eight-way array as a single volume. It includes a custom queuing system, configurable redundancy, provisions to extend NAND life, and support for both TRIM and the SCSI command set.
In the Z-Drive 4500, this novel controller architecture is paired with 19-nm MLC NAND from Toshiba. The Japanese flash maker purchased OCZ in December, so it's no surprise to see Toshiba NAND anchoring the latest Z-Drive.
The drive itself comes on a full-height, half-length card. A single-slot heatsink covers the circuit board, and temperature sensors combine with onboard intelligence to keep everything from overheating. If thermals exceed a set threshold, the Z-Drive will scale back its performance until temperatures return to normal.
The thermal throttling mechanism is new, and so are the drivers, which were redesigned from the ground up. Then there's the WXL caching software, which is OCZ's own. The software is being introduced alongside the Z-Drive 4500, and it's capable of using the entire drive as a cache or splitting the volume between separate storage and cache partitions.
OCZ is offering the Z-Drive 4500 in three flavors. Here's the run-down:
The prices are high, but so are the endurance specifications. The 3.2TB version is rated to withstand 2.5 petabytes of writes. Of course, the 800GB variant is rated for only 680TB of writes—just a little beyond the progress of our ongoing endurance experiment.
To put the Z-Drive 4500's endurance into perspective, recall that the old Z-Drive R4 3.2TB is rated for a staggering 120 petabytes of writes. The R4 has higher write performance ratings, too, but it's based on a full-length board, is much pricier (the 800GB version sells for $4,800), and has only three years of warranty coverage. Despite its lower endurance ratings, the Z-Drive 4500 has a longer five-year warranty.