Introducing the SF3700 Family

It's been a little over three years since we've seen a new controller from LSI SandForce and that was before the acquisition of SandForce by LSI. A number of competitors have released controllers that have really ratcheted up the competition so it's high time LSI answered the call. That answer comes with the in the form of their third generation SF3700 series controller that promises a host of improvements and innovations to help them attempt to regain the crown they wore for some time. With the SATA III interface not yielding much more in bandwidth, they'll need to do more than kick up read/write performance but rather focus more features. Not that performance improvements are absent. It mostly applies to enterprise applications but drive latency is much improved and claim tested client performance of 1,800MB/s in sequential reads (PCIe).

sf3700

This is the first flash controller with a single ASIC (application-specific integrated circuit) that can support both native PCIe Gen2 x4 and SATA 6Gbs host interfaces which means we'll be seeing an even wider array of drives come 2014 on both the consumer and enterprise markets. The change from PCIe to SATA comes simply via a change of a manufacturing jumper (plus firmware updates)  so don't get any cute thoughts about modding a drive to a different interface.

sf3700 Applications

The SF3700 controller will wear several hats serving up data for for everyone from entry level consumer applications, all the way to high-end enterprise solutions with support up to 2TB maximum capacity with a 9-channel ONFI-3/Toggle-2 flash interface. Each will carry their own part number and will be tailored the applications intended.

sf3700-performance

We're told that we'll begin seeing SF3700 based products in the first half of 2014 but were unable to get anything more specific than that due to existing non-disclosure agreements.

A closer Look At The SF3700

The architecture of the SF3700 is based off a 40nm process and is broken down into three basic components - the front-end, core, and back-end.

sf3700 architecture

The front-end is where the interface to PCIe or SATA lies and you can see both are called out on the diagram. The core is the brains of the operation handling everything from wear-leveling to encryption to drive mapping to all other maintenance duties like garbage collection and those under the DuraWrite technology.

durawrite

The DuraWrite technology has been improved to assist in the extension of the NAND life which is important when moving to smaller and smaller NAND lithography. The back-end is the NAND interface with all of the functions associated with NAND such as error correction.

sf3700 Error Correction

Added for this generation is the SHIELD error correction technology which LSI touts is the strongest SSD ECC available. As NAND lithography shrinks, the number of errors rise so this is a critical function. The adaptive nature of SHIELD partners with DuraWrite to flex the spare area to boost performance and longevity. It also can leverage the spare area in different ways as the drive ages to maximize performance. To supplement SHIELD, the controller also utilizes RAISE (Redundant Array of Independent Silicone Elements) to protect the data from unrecoverable ECC failures that SHIELD was unable to address.

raise

This existed in previous versions of the SandForce controllers but now protects against full die failures as well as multiple page and block in addition to the existing single page and block.

LSI

All in all, it's exciting to finally see this third generation of SandForce SF3700 controllers emerge and we look forward to getting some hardware samples to test out and see how it fares out in the wild. Again, we're told that mass production of OEM drives featuring these new controllers will occur in the first half of 2014 and we'd be shocked if we didn't see at least a few of these on display at CES in January. LSI has reference designs already built (M.2 2280, HHHL and 2.5-inch drives), so we are hopeful that retail product will be shown off real soon by their partners.

sf3700-reference-design

We expect to see a lot more consumer level PCIe drives in 2014 and this controller is part of the reason. Until then, we'll have to wait like everyone else to see how many announcements come out from various manufacturers about their new SF3700 based hardware.