An article by SSSI member Tom Coughlin on Self Encrypting Drives was just published in the October edition of Storage Networking Solutions. Tom defines SED, discusses the advantages of a SSD SED, and forecasts the rate of adoption of this important technology. It starts on page 17.
SSSI member Jim Handy at Objective Analysis has started a blog dedicated to SSDs. Jim is an avid follower of the SSD market, and his blog will doubtless be a great resource.
You’ll find the link on the SSSI Blogroll.
Objective Analysis has just published a new study with a somewhat surprising finding – that PCs get a bigger performance improvement by adding a dollar’s worth of NAND flash than by adding a dollar’s worth of DRAM.
This finding is the result of a series of nearly 300 benchmarks in which the company tested PCs with a variety of DRAM and NAND flash sizes running industry-standard benchmarks: PCMark, SYSmark, HDxPRT, and others.
In a nutshell the benchmarks showed that dollar-for-dollar NAND yields a greater performance improvement to a PC than does DRAM. Once PC users and OEMs discover this phenomenon there should be a mass-migration of PC architectures to systems with paired storage (there’s a SNIA Webcast on this), perhaps in hybrid HDDs, and this will present difficulties to DRAM makers whose biggest market is the PC.
Oddly enough, the study shows that the HDD is likely to remain in PCs for a while to come, since well-designed DRAM-Flash-HDD configurations perform nearly as fast as DRAM-SSD systems with prices and capacities that are similar to those of a conventional DRAM-HDD system. Future PC users are likely to opt for adding NAND flash, rather than DRAM, to their systems when they upgrade.
The report is available for purchase at http://Objective-Analysis.com/Reports.html#DRAM-NAND.
Comments and questions are more than welcome.
Apple recently announced Trim support for all SSD-capable Macs. What is Trim?
The SSSI Glossary defines the Trim command as “A method by which the host operating system may inform a NAND Flash-based SSS device about which blocks of data are no longer in use and can be erased. Such blocks may then be written without having to erase them first, enhancing SSS device write performance.”
A drive’s internal Garbage Collection performs a similar task as Trim by erasing blocks that have been previously marked for deletion. However, because of the way that many operating systems work, there will be some blocks that can be repurposed of which only the OS is aware; Trim addresses this issue.
For Trim to be functional, both the SSD and the OS must support it. Most SSDs of recent vintage support Trim, but check the features list to be sure.
In addition to the Apple OS, anyone who’s been paying attention knows that Microsoft Windows 7 supports Trim. And an increasing number of Linux versions support Trim, plus FreeBSD and OpenSolaris. Wikipedia has a more detailed list.
The best way to get flash memory into computers isn’t to replace HDDs but to augment them. For a vast majority of computer users the amount of storage they need is beyond what they can afford with flash memory alone. This trend is liable not to change in the future even as the costs of flash memory go down because HDDs will increase in storage capacity as well and the storage requirements of these users will increase as least as fast or perhaps even faster. However, these users would love to get a higher performing computer and putting some flash memory in combination with a hard disk drive could be a very attractive means to do this.
Hybrid HDDs that include some flash memory in the HDD are one approach but flash memory can also be installed in a computer motherboard or installed as a second drive. A recent report from Coughlin Associates and Objective Analysis explores these hybrid and paired storage and memory architectures. The main requirement to accomplish the performance and cost advantages of a paired storage systems in managing what is stored on the flash memory, and what on the hard disk drive. There are several software tools described in the report to provide this storage management. Paired and hybrid storage can also reduce system power use.
The combination of flash memory and HDDs is so compelling that the authors project a 53% adoption rate in desktop computers and a 25% adoption rate in notebook computers by 2016.
Furthermore, today’s media tablets will not provide for the needs of many business and power users who would like mobile products with more capability than can be provided by today’s tablets. This will lead to a new category of “fat tablet” computers that combine some flash memory with hard disk drives as well as other enhancements to meet this market need. The report projects that 40% of the total tablet market will be “fat tablets” by 2016.
The report can be ordered from Coughlin Associates at: http://www.tomcoughlin.com/techpapers.htm.
The white paper “Two May be Better than One: Why Hard Disk Drives and Flash Belong Together” has been posted at http://www.snia.org/forums/sssi/knowledge/education/. The paper discusses the use of both solid state storage and HDDs in the same system. Specific mention is made of Paired Storage, a configuration where a small SSD allows fast boot up and quick access to frequently used files and the HDD provides high capacity at a low cost per GB.
SDDs have tried to displace HDDs in computers for a few years but the higher cost of flash memory has been a major barrier to wide-spread adoption. Lower flash memory prices will help adoption but HDDs decrease in $/GB at about the same rate as SSDs so the relative ratio of prices doesn’t improve much in SSDs’ favor. At the same time there are serious issues in performance for many computers with HDDs, associated with the slower access time of HDDs.
There have attempts to combine the advantages of HDDs and flasy memory in the past such as Intel’s Turbo Memory and the hybrid hard disk alliance but these were mostly dependent upon the operating system to provide performance advantages. The latest initiatives to combine flash memory and hard disk drives to create tiered storage systems in computers are known as Blink Boot, hyperHDD and the solid state hybrid hard drive.
Most of these approaches (hyperHDD and solid state hybrid hard drive) don’t depend upon the operating system to manage the use of the flash memory and the HDDs. In the case of the recent solid state hybrid hard drive from Seagate the 4 GB of flash memory on the PCB board of the hard drive is used to store the most recently accessed data that the computer is using. This is done internally by the hard drive providing a boost in access speed for this content without any special requirements on the computer operating system.
By adding a little flash memory to a hard disk drive for frequently accessed data or even for OS and application booting while still keeping the HDD for inexpensive mass storage makes a lot of sense. Computer storage tiering with flash memory and HDDs could finally help flash memory become mainstream in computers.
Violin Memory introduced their 3000 series memory appliance in mid-May. This million-plus-IOPS device piles 10-20 terabytes of NAND flash storage into a single 3U cabinet at a price that Violin’s management claims is equivalent to that of high-end storage arrays.
The system, introduced at $20/GB, or $200,000, is intended to provide enough storage at a low enough price to eliminate any need to manage hot data into and out of a limited number of small solid state drives. Instead, Violin argues, the appliance’s capacity is big enough and cheap enough that an entire database can be economically stored within it, giving lightning-fast access to the entire database at once.
Note that Violin acquired Gear6 a month later, in mid-June. This seems to reveal that the company is hedging its bets, taking advantage of a distressed caching company’s expertise to assure a strong position in architectures based upon a smaller memory appliance managed by caching software.
There is a good bit of detail about how and why both of these approaches make sense in Objective Analysis’ newest Enterprise SSD report. See the Objective Analysis Reports page for more information.
But in regard to the Series 3000, CIOs whose databases are even larger than 10TB will be comforted to hear that Violin will be introducing appliances with as much as 60TB of storage by year-end.
Violin’s 3000 series can be configured through a communications module to support nearly any interface: Fibre Channel, 10Gb Ethernet, FCOE, PCIe, with Violin offering to support “Even InfiniBand, if asked.” Inside are 84 modules, each built of a combination of DRAM and both SLC and MLC NAND flash, configured to assure data and pathway redundancy.
This high level of redundancy and fault management is one of Violin’s hallmarks.
Violin’s website is Violin-Memory.com
San Francisco’s Nimbus Data Systems launched a solid state storage system in late April that is intended to replace all the HDDs used in a system except for slow disks used in near line storage. Nimbus holds a viewpoint that solid-state drives eliminate the need for fast disk storage, and that in future times all data centers will be built using only SSDs for speed and capacity drives (slow HDDs) for mass storage. This viewpoint is gaining a growing following.
Nimbus’ S-Class Enterprise Flash Storage System uses a proprietary 6GB SAS flash module, rather than off-the-shelf SSDs, to keep the costs low in their systems. Storage capacity is 2.5-5.0TB per 2U enclosure, and can be scaled up to 100TB. Throughput is claimed to be 500K IOPS through 10Gb Ethernet connections. Prices are roughly $8/GB.
Although Nimbus previously sold systems based on a mix of SSDs and HDDs, they have moved away from using HDDs, and expect for data center managers to adopt this new approach.
There’s merit to this argument, but it will probably take a few years before CIOs agree on the role of NAND flash vs. enterprise HDDs vs. capacity HDDs in the data center. There’s a lot more detail on the approaches being considered for flash in the enterprise data center in Objective Analysis’ new Enterprise SSD report. See the Objective Analysis Reports page for more information.
You can find out more at NimbusData.com
In London this week, I was invited to present on solid state storage at the SNIA Europe Data Center Academy event. It was a well-attended event with a good mix of IT managers, consultants and press in the audience – including Chris Mellor from The Register who subsequently published this blog. Chris is one of the most perceptive journalists in the industry and really nailed the key issues in his blog. Check it out!
BTW, the presentation is among the latest batch of SNIA tutorials, which you can find here.