SSD Interfaces

Where does NVRAM Fit?

AGIGARAM DDR4 NVDIMM (Photo Courtesy of AgigA Tech)There’s been a lot of interest in NVRAM recently.  This technology has been lurking in the background for decades, and suddenly has become very popular.

What is NVRAM?  Quite simply, it’s DRAM or SRAM that has a back-up flash memory a small controller, and a battery or super-capacitor.  During operation the DRAM or SRAM is used in a system the same way that any DRAM or SRAM would be used.  When power is interrupted the controller moves all of the data from the DRAM or SRAM to the flash using the backup power from the battery or super-capacitor.  When power is restored, the controller moves the contents of the flash back into the SRAM or DRAM and the processor can resume operation where it left off.

In some ways it’s storage and in some ways it’s memory, so Continue reading

White Paper: Matching Flash to the Processor

Moving flash into the memory channel to get fast parallel performance I have just added a new white paper onto the Objective Analysis website: Matching Flash to the Processor – Why Multithreading Needs Parallelized Flash.

This document examines the evolution of today’s CPUs, whose clock frequencies have stopped increasing, but now exploit parallelism to scale performance.  Multiple DRAM channels have also been added to performance computing to add parallelism to the memory channel.

Storage hasn’t kept pace with this move to parallelism and that is limiting today’s systems.

New NAND flash DIMMs recently introduced by Diablo, SanDisk, and IBM, provide a reasonable approach to adding parallel flash to a system on the its fastest bus – the memory channel.  This white paper shows that storage can be scaled to match the processor’s growing performance by adding flash DIMMs to each of the many DRAM buses in a performance server.

The white paper is downloadable for free from the Objective Analysis home page.  Have a look.

LSI SandForce SSD Controllers Move the Knee in the Curve

LSI SandForce SF3700 Controller DuraWrite ImprovementsLSI’s SandForce has just rolled out its SF3700 family of four SSD controllers aimed at the Entry Client, Mainstream Client, Value Enterprise, and Enterprise Storage marketplaces. Performance is impressive, with worst-case random PCIe IOPS at 150K read/81K write and 94K/46K for the SATA interface.

The SF3700 family builds on the division’s first two product families by adding a choice of PCIe or SATA interfaces, LDPC error correction, and a boosted set of flash management features.  The SSD Guy will explore this last point after highlighting the other two.

By providing both PCIe and SATA interfaces LSI is directly addressing the future: PCs are aiming to move to the m.2 SSD specification rather than Continue reading

Diablo: Flash Belongs on the Bus

Diablo TechnologiesDiablo Technology has just introduced a new set of DIMMs that put flash memory right onto the DDR3 memory bus.

I can already hear readers saying: “Wait!  You can’t do that!”  Well, you’re right, but the new module comes awfully close to that by putting the NAND behind an ASIC that interfaces between the DDR3 bus and the NAND.

Why do this?  Quite simply because you can get more “Bang for the Buck” by adding NAND to the system once you’ve reached a certain DRAM size.  The Diablo “Memory Channel Storage” (MCS) approach supports the addition of terabytes of NAND at the loss of Continue reading

WDC’s HGST Intros 12G SAS MLC SSDs

Latencey Histogram of HGST's MLC SSDIn case you didn’t have enough abbreviations in your life, The SSD Guy brings you the headline above, with the promise that the news below is really interesting: HGST (formerly Hitachi Global Storage Technology, but now a division of WDC – Western Digital Corp.) has brought out a new line of 12Gb/s SAS SSDs based on MLC flash.  These are a part of the UltraStar line.

Whereas HGST’s first-generation UltraStar SAS SSDs used SLC flash, the new SSDs are based on 25nm MLC flash but offer the same warranties as HGST’s prior generation.  Even so, performance for the new SSDs is significantly faster than that of their SLC-based predecessors, with no reduction in wear or lifetime specifications.

These SSDs are the first to support Continue reading

One-Hop vs. Two-Hop PCIe SSDs

Bunny HopLately a number of PCIe offerings have hit the SSD market.  The SSD Guy breaks them into two camps: One-Hop SSDs, in which the commands are translated directly from PCIe to the NAND flash without going through an intermediary protocol, and Two-Hop SSDs, which use off-the-shelf HBAs and SATA SSD controllers to move commands first from PCIe to SATA then from SATA to NAND.  There are aslo versions that go through SAS: PCIe to SAS, then SAS to NAND.

The SSD Guy figured that Easter would be a good time to talk about these since everyone already has the Easter Bunny hopping through their minds!

It’s not hard to understand why Continue reading

Intel Intros Fast Datacenter SATA SSD

IOPS Over Time - Competing SSD vs. Intel DC S3700Today Intel announced a new SATA III SSD, the DC S3700 Series.  The new product is fast, supporting 75,000 random 4K read IOPS and 36,000 random 4K write IOPS.  Average read latency is 45microseconds (µs) with writes averaging 65µs.  Sustained sequential reads are 500 megabytes/sec with sustained sequential writes at 460.  The read performance of this SSD, although a SATA device, is twice that of Intel’s 710 PCIe SSD announced in April, and writes are a full 15 times faster.  Intel calls this performance: “Scary fast!”

Intel says this device is its best Continue reading

Toshiba Announces its Hybrid Drive

Toshiba's New Hybrid DriveNow that we have seen announcements of hybrid drives from Western Digital and Seagate, Toshiba arrives with a formal announcement of the product that was on display at last month’s Flash Memory Summit.  Two 2.5″ Toshiba hybrid drives are starting to sample at 750GB and 1TB capacities.  Both have 8GB NAND caches, 6Gb/s SATA 3 interfaces, and 5,400RPM spindle speeds.  They are both built using 32nm SLC NAND, Toshiba’s “generation before last” technology, preceding the 24nm and 19nm nodes shipping in high volume today.

More importantly, both are 9.5mm in height, a thickness that renders them difficult to incorporate into the 18mm maximum thickness of the smaller Ultrabooks – a notebook form factor that Intel is heavily promoting.

How is this whole market Continue reading

Storage Developer Conference Focuses on SSDs

SNIA's 2012 Storage Developer ConferenceLast week the Storage Networking Industry Association (SNIA) hosted its 2012 Storage Developer Conference (SDC).  There was a strong focus on SSDs at this forum, with 15 papers, one keynote, and a panel devoted to the subject.

Consider that the 2008 SDC was the first such conference in which SSDs were discussed.  This year I commented to another participant: “Some day we will look back on this transition and be amazed at how suddenly SSDs became fundamental to the way storage is configured!”

Many of those papers and keynotes made it clear that the PCI Express (PCIe) interface has Continue reading

Link_A_Media Acquired by SK Hynix

SK Hynix Semiconductor Acquires Link_A_Media DevicesLink_A_Media, recently graced with a new design win and serious accolades for its new SSD controller, was acquired on June 20 by Korea’s SK Hynix Semiconductor.

According to the Wall Street Journal, SK Hynix paid $248 million for the company.

This is the fourth SSD controller company to be acquired recently:

What’s going on?  Why are Continue reading

Contact

Jim Handy
Objective Analysis
SSD Market Research
+1 (408) 356-2549
Jim.Handy (at) Objective-Analysis.com

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