Who uses SSDs, and why?

Posted on February 01, 2009

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BY JIM HANDY

The arguments of whether to use solid-state disk (SSD) drives vary depending on the market. In certain markets, SSDs are a very reasonable choice, while in other markets SSDs are unlikely to gain much traction.

Objective Analysis divides the data processing market into four sectors: budget PC, notebook, desktop, and server—each with different storage requirements.

Budget PC

The budget PC category includes very low-cost systems, such as Asus’ Eee PC, Intel’s Classmate PC, etc., These systems are price-driven, so their storage requirements are dictated by price rather than capacity.

Industry-standard hard disk drives (HDDs) have an absolute minimum price (com- monly referred to as the “floor price”) of around $35 to $50—they just can’t be built to meet a lower price target. Meanwhile, a low-density NAND chip can be purchased for less than $1. The net result is that NAND flash can be used to build less costly storage systems, giving more flexibility to the overall bill of material (BOM) cost. Even though the price per gigabyte of NAND flash is more than 10 times that of an HDD, a cost-constrained system will often use $20 or less of flash for storage rather than a $50 HDD.

The figure above (from Objective Analysis’ report, The Solid-State Disk Market: A Rigorous Look) is a graphic depiction of this phenomenon. As capacity increases beyond an HDD’s floor price, HDDs offer the lower price for any given capacity (the right side of the vertical line). At capacities significantly lower than the capacity of a single HDD, flash costs less than HDDs.

 

At low capacities, SSDs are less expensive than HDDs.

Flash memory has been successful in budget PC systems, but the low price of flash memory and the small unit volumes sold in this market prevent the NAND market opportunity from growing very large in this category.

Notebook PCs

For several reasons, most NAND-based SSD manufacturers are focusing their marketing efforts on the notebook PC:

  • The market is large and growing rapidly, with more than 100 million units shipping every year.
  • Notebook PCs have higher BOM budgets than do budget PCs, so more flash can be sold into these systems.
  • Notebook PCs benefit from the inherent advantages of SSDs—high read speed, silent operation, low power consumption, and less sensitivity to shock, vibration, temperature, and altitude.

To date, however, consumers have been slow to warm up to the notion of spending an extra $500 or so for these advantages.

So far, Objective Analysis has been relatively negative on the prospects of SSDs in the notebook market, although a new campaign launched by San- Disk is altering our viewpoint to some degree. SanDisk has found that today’s economic slowdown has caused IT managers to push out the deployment of new notebooks, asking users to hang on to their existing notebooks for another year or two. Today’s three-year-old PC typically includes 256MB of DRAM and a 20GB HDD. An IT manager can upgrade users’ DRAM to 2GB and replace the 20GB HDD with a 32GB SSD, giving users a significantly improved system at an additional cost of only about $75 per notebook.

Although we do not know how large the market is for such upgrades, it is conceivable that millions of PCs could be retrofit with SSDs, boosting the SSD market significantly while saving costs in IT budgets.

Desktop PCs

Very few of the SSD attributes that are being pitched to notebook users are relevant to desktop PC users. Power is rarely a concern with desktops, and the systems are not sub- jected to shock and vibration. And it is very rare that desktop PCs are subjected to extreme temperatures or altitudes.

As for the SSD’s higher performance, it seems that only very serious gamers are willing to pay a few hundred dollars extra for a drive that improves response time. And the final SSD attribute, silent operation, has only been an issue in home media centers—a market that has not developed as rapidly as once anticipated.

Objective Analysis sees little reason for SSDs to have any meaningful penetration into the desktop PC market unless low- capacity SSDs are used by IT managers to postpone deployment of new systems, as in the notebook example.

Servers

Although SSDs are unlikely to fare well in the notebook and desktop PC markets, the server market is a different story. Objective Analysis expects the enterprise server space to be the highest growth opportunity for SSDs.

To understand why SSDs are attractive in the enterprise space, you have to understand how data center managers build storage systems. Data centers are assembled using a large number of HDDs. Some are chosen for their capacity, while others are selected for speed. This is where you typi- cally see enterprise HDDs with faster interfaces, such as Fibre Channel and SAS, and with spindle speeds of 10,000 or 15,000rpm, as opposed to the 5,000 to 7,500rpm common in PC-based HDDs.

These faster drives, which have lower capacities and higher prices than PC HDDs, are used to crank up the system’s speed, but at a price premium. In some cases, even these drives are not fast enough, and a variety of techniques are used to coax more speed out of the storage system, such as striping (spreading the data across several drives to increase I/O speed), RAID, and short-stroking (limiting head movement to speed access at the expense of lost storage capacity.)

The figure above illustrates the storage hierarchy as a pyramid, where the short-stroked drives (which we dub “abused HDDs”) appear at the top, since they are few in number and high in cost, while fully-used enterprise HDDs and high-capacity HDDs fill in the middle and lower levels of the pyramid.

 

Since they are few in number and high in cost, short-stroked drives are most susceptible of being replaced by SSDs.

Short-stroked drives are the category that is most susceptible to being replaced by SSDs. IT managers find that they can replace a number of HDDs with a single enterprise SSD at about the same cost and realize higher performance with a smaller footprint, lower power consumption, and less cooling. Objective Analysis expects this market to represent the biggest opportunity for SSDs in the near term. Although a very small number of HDDs fall into this category, the high price of enterprise HDDs leads us to predict that the enterprise SSD market will grow to more than $1 billion by 2013.

Two-pronged development

SSDs are well-positioned to penetrate the two extremes of computing—the very low end and the very high end—for very different reasons. At the low end, SSDs give OEMs a price point that is much lower than HDDs. At the high end, SSDs reduce drive count and the power, space, and cooling costs that come with it, while maintaining or even increasing performance levels. In both cases, SSDs save money.

Objective Analysis expects the SSD market to develop in these two markets first, before appreciable progress is made in the notebook and desktop PC markets.  


JIM HANDY is director of the Objective Analysis semiconductor market research firm (www. Objective-Analysis.com).


SSD product roundup

By THE INFOSTOR STAFF

Here’s a quick rundown of some the more recent solid-state disk (SSD) drive announcements, with an emphasis on enterprise-class products:

  • At the Storage Visions Conference in Las Vegas last month, Samsung introduced the 2.5-inch, 100GB SS805 SSD with a random read speed of 25,000 I/Os per second (IOPS) and a random write speed of 6,000 IOPS, which company officials claim is more than 10x faster than 15,000rpm SAS hard disk drives (HDDs). Samsung officials also claim that the SSD can process up to 100x the number of IOPS per watt compared to 2.5-inch, 15,000rpm SAS HDDs.

The SSD drives use 1.9 watts of power in active mode and 0.6 watts in idle mode. In comparison, traditional 15,000rpm HDDs consume 8 to 15 watts in active mode and 1 to 2 watts in idle mode.

In terms of throughput, the SS805 has a sequential read rate of 230MBps and a sequential write rate of 180MBps.

Samsung officials attribute the performance improvements to an 8-channel controller, improved NAND flash memory (based on single-level cell, or SLC, technology), and new firmware. Data encryption is included with the SSD drive.

  • Imation also used the Storage Visions Conference to launch two SSD lines—the 2.5-inch M-Class and 3.5-inch S-Class—with capacities ranging from 32 to 128GB. The company offers an upgrade kit that allows users to replace HDDs with SSDs. The kit includes a SATA or USB-to-SATA connector cable, power cable, and Acronis’ True Image HD software for migrating operating systems, applications, and data from an existing drive to the SSD.

The M-Class SSD drives are priced at $179.99 for a 2.5-inch configuration with 32GB of capacity and a SATA interface. The S-Class drives will be available in March.

  • STEC has added 3Gbps SAS interfaces as an option on its ZeusIOPS SSDs, which are also available with Fibre Channel interfaces. The 2.5-inch SAS-based SSDs are available with 100 or 200GB, and a 3.5-inch version has up to 400GB of capacity. STEC claims a read performance of up to 45,000 IOPS. The SSDs are based on SLC NAND technology, and include features such as full data path protection and dual ports.
  • Intel recently began production shipments of both an enterprise-class SSD (the X-25E) and notebook/desktop-class SSDs (the X18-M and X25-M).

The 32GB X-25E is based on a SATA interface and SLC NAND flash memory technology, and includes performance specs of 35,000 IOPS (with 4KB random reads), 3,300 IOPS (with 4KB random writes), and 75-microsecond latency. At 2.4 watts in active mode, the drive delivers up to 14,000 IOPS per watt. Throughput specs on the 2.5-inch drive include 250MBps for sequential reads and up to 170MBps for sequential write operations.

Other features of Intel’s X-25E SSD include a 10-channel NAND architecture with native command queuing (NCQ), and wear-leveling technology. The 32GB model is priced at $695 in quantities up to 1,000 units. Pricing for the 64GB version has not been established (sampling began in Q4 2008).

Intel’s notebook/desktop X18-M (1.8-inch) and X25-M (2.5-inch) SSDs are based on multi-level cell (MLC) NAND technology, and are available in 80 or 160GB versions. Priced at $595 in quantities up to 1,000 units, the 80GB version delivers up to 250MBps read speeds, up to 70MBps write speeds, and a 85-microsecond read latency.

One million IOPS

Texas Memory Systems claims a random read performance of one million IOPS (or more with a Turbo feature) for its RamSan-5000 SSD, which is based on a combination of up to 20TB of RAID-protected flash memory and a DRAM cache of up to 640GB. The company also claims a response time of less than one millisecond, and 20GBps of read or write bandwidth using either Fibre Channel or InfiniBand interfaces.

The DRAM cache on the RamSan-5000 accelerates writes, while the flash memory accelerates read performance. The SSD requires 3,000 watts of power, and occupies 40U of rack space.

  • Last month, Toshiba America Electronic Components (TAEC) entered the enterprise-class SSD market by announcing its first SLC-based NAND devices, which come with a SAS interface. The 2.5-inch SSDs come in 50 or 100GB versions. Toshiba claims performance of 25,000 IOPS with 4KB reads and 20,000 IOPS with 4KB writes. The company plans to begin sampling the drives next month, with production shipments scheduled for the second quarter.

In December, Toshiba introduced new SSDs designed primarily for notebooks and gaming and home entertainment systems. The 2.5-inch, 512GB drives are based on MLC NAND flash memory technology. Samples are available now, with production shipments scheduled for the second quarter. Toshiba claims a maximum sequential read speed of 240MBps and a maximum sequential write speed of 200MBps. The drives come with AES encryption.

Networked SSDs

In a twist on the standard SSD theme, Fusion-io has introduced the ioSAN, which can be deployed as networked, server-attached, or integrated into existing networked storage infrastructures. The ioSAN combines Fu-sion-io’s ioMemory and Converged Enhanced Networking technologies, essentially allowing users to deploy off-the-shelf servers to create an SSD-based SAN. Interface options include 10GbE or 40GBps InfiniBand. The company claims that users can create SANs capable of millions of IOPS with less than 1 ms of latency.

  • BiTMICRO Networks’ latest entry in the enterprise SSD space is the E-Disk Altima E3F4FL, a 3.5-inch device with a 4Gbps Fibre Channel interface. Based on SLC NAND flash memory chips, the SSDs come in capacities ranging from 128GB to 1.6TB. The company claims sustained throughput rates of 230MBps and up to 55,000 IOPS. Targeted applications include streaming video on demand, data mining and warehousing, OLTP, medical imaging, and data recording.
  • Super Talent Technology is shipping SATA-based SSDs with up to 256GB of capacity. The latest entry is the enterprise-class UltraDrive LE, a 2.5-inch drive with SLC NAND flash technology, a maximum read rate of 230MBps, and a maximum write speed of 170MBps.

Super Talent is also shipping the 2.5-inch notebook-class UltraDrive ME SSDs, which are based on MLC technology, with capacities up to 256GB. The company claims a maximum read rate of 200MBps and a maximum write rate of 160MBps.

  • pureSilicon recently began shipping its Renegade SSDs, which include 256-bit, hardware-based AES encryption that is compliant with the FIPS and MIL-STD-810F standards. Features of the ruggedized SSDs include up to 128GB of capacity, extreme temperature range components, and high shock and vibration tolerances.
  • Olixir Technologies’ ruggedized, military-grade SSDs include the new Mobile DataVault FMX line, with capacities ranging from 8 to 128GB. The flash-based transportable devices are designed for harsh environments, and can withstand shock in excess of 12,000 G's and 90 G's of vibration during operation. Interface options include USB 2.0, Firewire, eSATA or SATA.
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