endurance

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

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

SMART Optimus Ultra+ SSD: SLC Performance Using MLC Flash

SMART Guardian vs Normal Flash Management - More good BlocksSMART Storage Systems has introduced a new enterprise-class SSD that the company says: “increases the endurance of cMLC Flash to a level that makes SLC drives obsolete.”  That’s a pretty hefty claim!

The new Optimus Ultra+ SSD is specified at 100K read IOPS and 60K write IOPS, through its 6Gb/s SAS interface.  With capacities ranging from 100-800GB, this SSD supports up to 50 full drive writes per day over its 5-year lifespan, double that of the company’s Optimus Ultra which was introduced in February.  That’s quite something for an MLC-based SSD.

SMART has tapped into its Guardian technology to reap SLC benefits from MLC flash through both enhanced external and internal algorithms.  Like all other SSD makers and SSD controller makers SMART has focused a lot of attention on error correction, DSP, and other means of correcting errors externally to the flash.  The company has also partnered with Continue reading

What Happens when SSDs Fail?

What happens at the end of an SSD's life?There’s a lot of “Fear, Uncertainty, and Doubt” – FUD – circulating about SSDs and their penchant for failure.  NAND flash wears out after a set number of erase/write cycles, a specification known as the flash’s endurance.

While some caution is warranted, a good understanding of how SSDs really behave will help to allay a lot of this concern. Continue reading