Tag: TLC

How Controllers Maximize SSD Life – External Data Buffering

Tempus FugitSince NAND flash is weakened by erase/write cycles then it would make sense to try to reduce those cycles to prolong the life of an SSD right?  That’s what external data buffers are designed to do.

There are many ways to use RAM (either a RAM internal to the SSD controller chip or a discrete DRAM chip on the SSD’s printed circuit card) to stage data in a way that will reduce erase/write cycles.

One is to perform a function called “Write Coalescing.”  This involves Continue reading “How Controllers Maximize SSD Life – External Data Buffering”

Samsung Introduces TLC SSD

This Graphic Illustrates the Challenge of TLC FlashSamsung on Monday introduced a new “840” SSD series which reviewers have found is based on TLC flash.

Oddly enough the press release for this product seems only to have been distributed in Korea to reviewers who attended a special introduction of the device.  The SSD Guy has not been given the specifications presented at the event, and had to ask Samsung for a copy of the press release.

The press release focuses on the product’s 100,000 read IOPS, that it comes in two versions, the “Pro” model for the enterprise and another model for client applications, and the fact that the controller uses a new design based on three ARM cores. A read IOPS figure of 100,000 is very high performance for a SATA drive!  One has to wonder if the client market will be able to distinguish between this level of performance and drives with fewer than 10,000 IOPS.

Other specifications Continue reading “Samsung Introduces TLC SSD”

How Controllers Maximize SSD Life – Better Wear Leveling

Tempus FugitIn this post we will explore how the right wear leveling algorithm  can help a controller maximize the life of an SSD.

Wear leveling is a fact of life with NAND flash – blocks start to suffer bit failures after a certain number of erase/write cycles (usually specified from the thousands to the hundreds of thousands) and it is only natural that software will attempt to over-write some blocks more than others.  In order to prevent this from causing failures, all of today’s SSD, USB flash drive, and flash card controllers incorporate some sort of wear leveling.

This is a simple re-mapping of the contents of the flash chips.  A more graphical explanation is Continue reading “How Controllers Maximize SSD Life – Better Wear Leveling”

How Controllers Maximize SSD Life

Tempus FugitHow do controllers maximize the life of an SSD?  After all, MLC flash has a lifetime of only 10,000 erase/write cycles or fewer and that is a very small number compared to the write traffic an SSD is expected to see in a high-workload environment, especially in the enterprise.  Still, MLC is becoming the norm in the enterprise.

How do they do that?

This is where SSD architects really earn their pay.  There are eight basic techniques that The SSD Guy knows of to extend SSD life beyond Continue reading “How Controllers Maximize SSD Life”