Enterprise-class SSDs use costly SLC NAND or, more frequently, eMLC flash. But Micron's RealSSD P400e raises eyebrows by using low-cost MLC memory. Does this make sense on an SSD fighting for the affections of data center managers with read-heavy apps?
True enterprise-oriented SSDs are very expensive, and the SLC (single-level cell) NAND typically used in these solid-state drives is a major reason why. SLC NAND provides high performance data access and long-term endurance in demanding enterprise I/O environments, but, as we've seen time and again, is quite costly. In contrast, MLC (multi-level cell) NAND is far cheaper, but delivers slower write speeds, fewer program-erase cycles, and higher power consumption.
Given the significant premium on enterprise-class SSDs, there's an increasing emphasis on bridging the gap between the endurance, performance, and cost of SLC- and MLC-based drives. But is it even possible to achieve the I/O performance and long-term reliability heavy enterprise workloads require using consumer-grade MLC NAND?
We all recognize the potential of fast SSDs in demanding environments, after all. But magnetic storage is still most prevalent. Most IT professionals would welcome a transition to solid-state technology if it could be made less expensive, particularly in read-heavy applications where endurance isn't as pressing of a concern.
Micron's P400e is designed specifically to satisfy that space. A near twin of the consumer-oriented Crucial m4, Micron's P400e shares the same Marvell 9174 SATA 6Gb/s controller and 25 nm MLC NAND. In fact, the two SSDs are so similar that we found ourselves wondering: what, precisely, differentiates the P400e as an enterprise-grade SSD?
According to Micron, the P400e is equipped with firmware designed for read-heavy enterprise workloads, including 28% over-provisioning and data protection via memory path error correction. The company sees this drive deployed to address a wide range of business applications where SLC-based hardware might have been cost-prohibitive in the past. This partly explains why the P400e is manufactured to a 7 mm Z-height. It is possible to install the drive in the 9.5 mm standard form factor using a shim, making it easier to deploy in 1U/2U servers and more common hard drive racks.
|Micron RealSSD P400e |
|Raw NAND||64 GB||128 GB||256 GB||512 GB|
|User Capacity||50 GB||100 GB||200 GB||400 GB|
|Sequential Read||350 MB/s|
|Sequential Write||140 MB/s|
|4 KB Random Read||50 000 IOPS|
|4 KB Random Write||7000 IOPS|
|Power Consumption (Active)||2.5 W for 50 GB|
Up to 5 W for 400 GB
Like the Crucial m4, Micron's RealSSD P400e is available in four capacities: 50, 100, 200, and 400 GB. However, the P400e's performance specifications fall a bit short of most SATA 6Gb/s-equipped SSDs we test (most notably the m4 that this drive looks a lot like), rated for 350 MB/s sequential reads, 140 MB/s sequential writes, 50 000 random read IOPS, and 7000 random write IOPS.
Acknowledging that reliability is more important than the performance of what we'll call an "entry-level" enterprise SSD, Micron deliberately alters its firmware to put more emphasis on trouble-free operation. The company hopes its approach may help prevent some of the firmware-related idiosyncrasies that plagued Crucial's m4 (and indeed, many other desktop-oriented drives that see three or four updates to correct show-stopping issues).