Client SSDs – Page 11 – The SSD Guy Blog

Standards for SSD Endurance

SSD endurance is an important concern that stands in the way of SSD adoption in a number of data centers. Since flash is new to the enterprise (and computing systems are a new market for flash) important issues including wear specifications still need to be hammered out.

Until flash SSDs started experiencing adoption in standard computing environments, nobody really anticipated the difficulties that would arise from flash’s inherent wear-out mechanism. Most flash manufacturers erroneously believed that Continue reading “Standards for SSD Endurance”

How Will Thai Floods Impact the SSD Market?

In early November The SSD Guy published a post that argued that Thailand’s floods would not make much difference to the SSD market.

Since that post not only has the argument gone less in favor of SSD adoption (thanks to a high level of HDD finished inventory, some changes in shipping practices, and a heroic effort from Thailand’s HDD makers and the Thai people to overcome this disaster) but the promotional efforts in favor of SSD adoption have become stronger.

Objective Analysis has spoken since the floods with a number of companies who either produce HDDs or HDD sub-assemblies, or consume HDDs, and this is what we have found:

Continue reading “How Will Thai Floods Impact the SSD Market?”

Victorinox’ Terabyte-in-Your-Pocket

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”

SandForce: The Cloud needs Different SSDs

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”

New Seagate Hybrid Drives: 2x the Flash, 2x the I/O Speed

Seagate has just announced an upgrade to the company’s Momentus XT hybrid HDD family. Seagate announced in August that the company had already shipped over one million units of its first generation Momentus XT since its May 2010 introduction.

For those unaware of what a hybrid HDD is, the short answer is that it’s a way to get HDD capacities and SSD speeds at a price marginally higher than that of an HDD. Continue reading “New Seagate Hybrid Drives: 2x the Flash, 2x the I/O Speed”

SSDs and Caching

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”

SSD Fast Erase

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”

What Happens when SSDs Fail?

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?”

SSD Garbage Collection

garbage cans 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”

Sometimes SSDs Don’t Improve System Speed

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”