Solid State Drives (SSD) continue to be super-hot, as the aisles of Storage Networking World (SNW) demonstrated earlier this month. It seemed that half the vendors were touting their latest flash products.
And the flames are being fanned by steadily falling prices –- about 50 percent per year. That has some forecasting the end of the hard disk. But Jim Handy, an SSD analyst for Objective Analysis said that is never going to happen. SSD prices may be dropping rapidly, but hard drive prices are falling just as fast.
"It's like the old cowboy gag about the gunslinger saying, 'stand still so I can shoot you'," said Handy. "Both SSD and hard disk drives (HDD) are on a trajectory per GB to drop at 50 percent per year."
Nevertheless, there are plenty of compelling reasons to adopt SSDs. Here are some of the innovative applications of this technology discovered at SNW.
Virident has a PCIe-based SSD offering similar to FusionIO. The differentiators, though, are sustained performance and replaceable flash modules. It is known as Virident tachIOn PCIe SSD, and it is available in cards with 300, 400, 600 and 800 GB. "You can replace our flash modules without having to replace the card," said Jon Murphy, VP Channels. "In addition, most other approaches to SSD can't sustain performance over time under load."
Virident stabilizes high SSD performance courtesy of its two-controller architecture. Moving forward, Murphy expects PCIe deployments to dominate over the traditional HDD form factor for SSD. Reason: Having data near to the application CPU gives you far higher compute rates compared to using SAS/SATA-connected technologies that are employed when you plug the SSD into a hard drive slot.
Viking Modular Solutions offers high-capacity SSD for enterprise storage and server applications. Known as SATADIMM, it provides 60,000 IOPS, 6 Gb/sec SATA performance (is SAS compatible), has a 75 percent smaller footprint than traditional SSD (which uses a 2.5 inch HDD form factor), and it plugs into the DDR3 DIMM sockets used in memory.
"Why stick with the traditional SSD form factors when you gain so much by plugging it into DIMM sockets," said Jonathan Hinkle, memory systems architect at Viking. "Instead of replacing cheap drives with SSD and thereby lowering storage capacity, keep the SATA disks in place and utilize spare DIMM sockets for flash."
Systems that currently use massive amounts of RAM, for example, could replace some memory with a few TB of flash and be able to provide high performance for a much higher data set, he added. SATADIMM is available in sizes of up to 480 GB.
StorSimple 5000 and 7000 hybrid cloud appliances include an SSD top tier. The company augments this by deduplicating data in the background once it is written to SSD. That reduces the amount of data that must be sent across the WAN to the associated cloud services provider such as Amazon, EMC Atmos, AT&T, Zetta or Microsoft.
"We duplicate within a separate layer within the SSD so it doesn't interfere with any ongoing writes," said Ian Howells, chief marketing officer of StorSimple. "90 percent of active data can be read from within an SSD."
SMART Modular Technologies' XceedIOPS2 SATA 1.8" and 2.5" SSDs are equipped with the SandForce SF-2000 series SSD processor as well as a 6Gb/s SATA interface. This delivers 60K IOPS and sequential performance of 520MB/s, as well as encryption. It is available in densities from 50 GB to 400 GB.
One key thing to understand about SSD is the subject of endurance levels as measured in program/erase (P/E) cycles -- i.e. how many times can you write, then erase and rewrite on a flash cell? This is important in comprehending the various types of cell technology used. There is single-level cell (SLC) and multi-level cell (MLC). While vendor estimates and counting methodologies vary, Mike Lakowicz, director of storage at SMART, said MLC typically offers up to 3000 P/E cycles, whereas SLC gives as much as 50,000 to 100,000 cycles. MLC Flash devices provide greater storage capacity, while SLC Flash provides faster write performance and greater reliability. Thus, many of the first wave of enterprise SSDs used SLC.
But various vendors, including SMART, have been working on enterprise-grade multilevel cell (E-MLC) technology, which Lakowicz said offers 30,000 P/E cycles. With SLC costing around $10 per GB, MLC at $2 to $3 and E-MLC at $4 to $5, he said that the company's E-MLC products provide high reliability and performance comparable to SLC. He confessed, though, that it wasn't perfect for all uses cases.
"If you are doing 100 percent writers all the time, use SLC," said Lakowicz.
IDC said it is seeing a trend away from SLC towards MLC. The analyst firm is predicting 170 percent average annual revenue growth for MLC-based enterprise SSDs during the next four years.
"Data center applications, cloud computing and servers are increasingly looking toward SSDs based on MLC flash to satisfy the demands of enterprise economically," said Jeff Janukowicz, an analyst at IDC. "Enterprise SSDs using MLC flash with advanced performance and state-of-the-art controller technologies, include SMART's new XceedIOPS2 SATA SSD."
Micron Technology is another in the MLC camp. It offers SLC for some enterprise-class products, but it has just come out with a laptop device called the RealSSD C400 using MLC. Pricing for it should be not much more than $100 for a 64 GB version, which begins to make it very attractive for broad deployment. It has a couple of small form factors available (1.8 inch and 2.5 inch) in sizes from 64 GB to 512 GB, and it supports the SATA 6Gb/s interface, which opens up the data path between the host processor and the SSD.