Intel has announced a new SSD for the Enthusiast/Gamer market. Intel’s fastest drive to date, this SSD, formerly known as “Cherryville” but now called the 520, is the first Intel SSD to use a SandForce/LSI controller and is made using Intel’s own 25nm flash.
Intel worked with SandForce for a year and a half to produce an SSD that met Intel’s rigorous standards, and made hundreds of changes to SandForce’s firmware. Users of SandForce controllers can differentiate their SSDs through the addition of features in the SSD controller’s firmware. Intel did this by tapping into its expertise in end-to-end data protection (something the company learned when working with Hitachi to introduce that company’s Intel-based enterprise SSDs) while harnessing Intel’s deep understanding of its own NAND flash and of the I/O needs of the PC.
End-to-end data protection is not a trivial feature: Continue reading “Fast New Intel SSD: The 520”
At The Consumer Electronics Show this week, Swiss army knife maker Victorinox introduced a one-terabyte SSD in a form factor similar to a fat Swiss army knife. Yes, that is right – a terabyte of NAND flash in your pocket. The company tells us that the device’s dimensions, including the connector, are a scant 52x18x10mm.
Some of the other features include the use of an eSATA connector (to allow the product to be plugged into either a SATA port or a USB socket), AES256 encryption (any army would like this), and a bi-stable LCD to tell how much free space remains on the device.
But let’s look at the difficulty of building a 1TB flash SSD in such a small space:
Continue reading “Victorinox’ Terabyte-in-Your-Pocket”
On Monday December 13 SandForce introduced SSD controllers designed specifically for cloud computing applications.
You might wonder what is so different about cloud applications that they need an SSD controller of their own. SandForce makes some interesting points:
- Cloud applications need low latency
- Cloud computing centers, like client SSDs, need a lot of capacity at a very low price Continue reading “SandForce: The Cloud needs Different SSDs”
The SSD guy usually argues that NAND flash (as an SSD) fits into the memory/storage hierarchy for two reasons:
- SSDs are cheaper than DRAM but more expensive than an HDD
- SSDs are slower than DRAM but faster than an HDD
An SSD is usually a very good alternative to adding more DRAM to a system, but this is not always the case. Users need to look carefully at the SSD they plan to use to make sure they are getting the most for their system spend. Continue reading “DRAM vs. SLC SSD – Which Makes More Sense?”
One of the SSD Guy’s favorite subjects is caching and SSDs. This is because I wrote a book on processor caches in the early 1990s, and the advent of SSD caches in storage systems hearkens back to the technology detailed in that book.
Caching works well whenever there are two layers in the memory hierarchy since the fast expensive layer can replicate data in the slow inexpensive layer to accelerate the processor’s performance. Continue reading “SSDs and Caching”
An interesting feature that exists in many SSDs is the ability to quickly erase all the data on the device. The military is especially interested in this feature because it helps prevent sensitive data from falling into the wrong hands.
For example, let’s say your helicopter crashed when on a mission to assassinate the leader of a major terrorist organization. If the HDD or SSD inside the cockpit was recovered by that organization the data might be extracted to help undermine future missions. Continue reading “SSD Fast Erase”
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 “What Happens when SSDs Fail?”
The SSD Guy has been asked a number of questions lately about SSDs and RAID. Most of these center around the difference in failure behaviors between SSDs and HDDs – HDDs fail randomly (if ever), while SSDs fail relatively predictably due to wear.
Oddly enough, SSD failures due to wear make them a little friendlier than HDDs. The wear mechanism is managed by the controller in the SSD. SSDs have spare blocks, and the controller manages those blocks, so the controller understands exactly how much wear the SSD has undergone and how much room is left before the SSD will start to have difficulties. Continue reading “SSDs and RAID”
One of the thorniest issues in SSD design how to manage erasing blocks that are no longer in use. That’s saying a lot, because NAND flash presents so very many difficult challenges like wear leveling, bad block management, error correction, and write amplification.
The difficulty stems from the fact that all of today’s software was written for HDDs which don’t behave like the flash in an SSD. An HDD can over-write existing data with new data. In a flash SSD, a block must be erased before being over-written and this can take a half a second – a huge amount of time in the world of computing. Since the software doesn’t accommodate flash’s “erase-before-write” needs, the controller inside the SSD must take care of this bit of housekeeping. Unused and unerased blocks are moved out of the way and erased in the background. This is called the “garbage collection” process. Continue reading “SSD Garbage Collection”
The SSD Guy attended TechTarget‘s Storage Decisions Conference last week in San Francisco. Dennis Martin of Demartek gave a very good presentation called Making the Case for Solid-State Storage.
Demartek tests a lot of systems based on various forms of storage.
I really liked an expression that Mr. Martin shared to compare SSDs to HDDs. He said that SSDs cost dollars per gigabyte and pennies per IOPS, while HDDs cost pennies per gigabyte and dollars per IOPS. This is a really good way to think about the strengths and weaknesses of these two technologies. There is every reason to use a mix of both. Continue reading “Sometimes SSDs Don’t Improve System Speed”