SSD Buyers Guide - StorageSearch.com


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the Solid State Disks Buyers Guide - 2004

by Zsolt Kerekes editor of StorageSearch.com

click here for an updated version of - the SSD Buyers Guide

SSD Market History
the Top 10 Solid State Disk Companies
SSD Myths and Legends - "write endurance"
RAM SSDs versus Flash SSDs - which is Best?

	Solid State Disks Product Category of the Year 2004 on StorageSearch.com

I contacted every manufacturer of SSDs and visited every SSD web site in October and early November 2004 to compile data for this article and also datamined the SSD stories we ran during the past year. All SSD user statistics quoted in this article are preliminary data from the STORAGEsearch SSD Survey which ran in Q404.

Why Do People Use Solid State Disks?

#1 - Application speedup - cited by 76% SSD buyers.

#2 - Environment is unsuitable for hard disks cited by 31% SSD buyers.

How is this Guide Organized?

Last year's SSD guide was organized by ascending price, but our SSD Survey showed that speed, form factor and interface compatibility are the factors by which most users initially select SSD products with price ranked as relatively unimportant. Scrolling down this page you will see 4 main tables grouped by form factor and interface type. This guide also discusses the differences between different SSD technologies - where the differences matter - and where they don't - and looks at future technologies which could impact this market.

What are the Main Changes in the Market Since 2003?

SSD companies made a strong showing in our list of the Fastest Growing Storage Companies in 2004. Many SSD companies who didn't make the list because of revenue size or being privately owned have also said to STORAGEsearch that they have been seeing high double digit revenue growth.

Who's In? Who's Out?

As technology markets get bigger it's inevitable there will be shake-outs as users are more easily able to compare features and seek competitive pricing. IEI (renamed this year to QNAP) has dropped its NAS flash SSD product. Also some semiconductor makers ended their SSD module lines. Platypus Technology and Imperial Technology went bust in 2003 but Imperial has re-emerged, scaled down and under new ownership. Some other companies from last year have been dropped from this list because we've sharpened the focus to exclude low speed consumer flash products which aren't regarded as true SSDs. Many of the companies in the SSD market have been around for one or two decades, but this year we've seen the first of what will be a new wave of oems emerging from stealth mode with the entry of SiliconSystems.

The Emergence of Channels

When IT markets are small and nichey - users work hard to find manufacturers - and niche manufacturers lean heavily on personal selling. As markets get bigger, so too does the range of user needs and applications, and manufacturers have to learn new marketing skills. The recent emergence of reseller channels in the SSD market is a sign of growing maturity. Dynamic Solutions International which sells SSDs into financial institiutions in the US and Europe is one of the longest established SSD VARs in the non military sector. Computer Expertise Group, founded by a manager in Imperial, is a specialist supplier of refurbished solid state disks. In October 2004 - Sun Microsystems (in the UK) became a reseller for Texas Memory Systems' RamSan products. I predict that in 2005 IBM, HP and Fujitsu will follow suit and start more actively promoting this technology to users of their larger systems. See article:- Charting the Rise of the Solid State Disk Market

Capacity

SSD storage density follows Moore's Law and doubles every 18 months or so. Several manufacturers including SimpleTech and M-Systems anounced 2.5" ATA compatible flash disks with an incredible 128GB capacity. In March 2004 BiTMICRO claimed a world record by packing 155GB into a 3.5" fibre-channel flash disk delivering 9,800 IOPS. If speed is more important to you than space and rugged environmental survival Texas Memory Systems doubled the capacity of their 250,000 IOPS 3U fibre-channel RamSan to 128GB in November 2004 and disclosed that many customers had been buying terabyte size SSD systems.

Solid State Disks by Form Factor - Part 1 - Classic HDD Types
72.4% of SSD users said that traditional hard disk packages are the most suitable for their requirements, and this is reflected in the large number of oems who make such modules. Standard 2.5" or 3.5" SSDs can be integrated in current server disk storage bays without any modications. 27.6% of SSD users said that rackmount suited their needs. The biggest SSD users have multiple applications for products. 30.4% of all users said their budgets for SSDs were over $100,000. Re rackmount SSD systems:- the companies listed below offer standard factory supplied systems, but in fact you can install standard sized 2.5" or 3.5" SSDs into a JBOD in exactly the same way as a conventional hard disk drive.
1.8"	2.5"	3.5"	rackmount
Memtech M-Systems	Adtron BiTMICRO Networks Afaya Altec ComputerSysteme Hagiwara Sys-Com Memtech M-Systems Pretec Electronics SiliconSystems SimpleTech Targa Systems Division Unigen Winstation Systems	Adtron Altec ComputerSysteme BiTMICRO Networks Curtis Hagiwara Sys-Com Memtech M-Systems	Asine BiTMICRO Networks Curtis Imperial Technology SEEK Systems Solid Data Systems Taejin Infotech Texas Memory Systems TiGi Vanguard Rugged Storage

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AT1830 Mustang low power 1.8" rugged solid state disks from Memtech

1.8" low power rugged
solid state disks
from Memtech

Speed and Capacity Aren't Everything in Embedded Solid State Disk Systems

Although server speedup applications always do need fast high capacity disks, and many embedded applications have similar requirements, at the other end of the scale is a requirement for low power operation and the ability to survive high G forces and temperature ranges.

These types of deployments range from terrestrial to space vehicles, data loggers, point of sale systems, communications systems and traffic control systems. They usually don't need high storage capacity because they are running real-time operating systems which are much more efficient at using memory. But when the whole system is running off a battery with a tight power budget - every milli-amp counts.

Buyers can choose from a range of SSD products which are optimized for weight, space, power, speed, capacity, rugged operation or a combination of factors. The more ticks in the box the more expensive the disk. So it's important not to over specify.

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M-Systems, 3.5" Ultra Wide SCSI Fast Flash Disk

3.5" Ultra Wide SCSI Fast Flash Disks
from M-Systems

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Solid State Disks by Interface - Part 1 - the Usual Suspects
The overwhelming majority of SSD users said that conventional hard disk interfaces met their needs. Nearly all flash USB drives are too slow to be considered in this SSD context as server speedup storage. See Flash Memory and USB storage.
SCSI	SAS	Fibre-channel	Parallel ATA / IDE	SATA
Asine BiTMICRO Networks Curtis Memtech M-Systems SEEK Systems Solid Data Systems Targa Systems Division TiGi	BiTMICRO Networks	BiTMICRO Networks Curtis Imperial Technology Solid Data Systems Taejin Infotech Texas Memory Systems TiGi	Adtron Afaya Asine BiTMICRO Networks Hagiwara Sys-Com Memtech M-Systems Pretec Electronics SiliconSystems SimpleTech Targa Systems Division Unigen Winstation Systems	Adtron

Tera-RamSan - terabyte solid state SAN storage

Tera-RamSan Enterprise SSD Array
1 Terabyte of Non-Volatile DDR RAM
from Texas Memory Systems

Why Are Solid State Disks Faster than Hard Disk Drives?

In multi user systems and most applications (excluding streaming video) the most important factor which affects I/O Operations Per Second (IOPS) is the random access time to seek data. In mechanically rotating media like hard disk drives the average access time depends on the disk platter rotation speed. At 15,000 RPM half a spin cycle takes 2 milli-seconds. In SSDs, data is stored in semiconductor memory which can be randomly accessed in microseconds or less. When taking into account the overhead of interpreting disk commands this results in IOPS for commercially available SSDs which are typically 50 to 1,000 times faster than IOPS for commercially available hard disk drives.


Solid State Disks by Interface - Part 2
Infiniband has been mentioned on the sites of vendors listed but is not necessarily native, and involves a router system. Texas Memory Systems offer a solution in partnership with Topspin Communications. Infiniband will be an important interface for SSDs in the future because it will enable server owners to get the most benefits from fast storage. The current generation of 1Gbps iSCSI networks needs hardware host bus accelerators to match SAN speeds and the installed base of iSCSI is still small. So it's doubtful whether iSCSI will be more than a niche market for SSDs until Ethernet speeds move up to 10Gbps. Some SSD companies also offer products with interfaces to specialized Military busses such as 1553..
iSCSI	NAS	InfiniBand	FireWire
BiTMICRO Networks	BiTMICRO Networks Taejin Infotech Targa Systems Division	Texas Memory Systems	Altec ComputerSysteme BiTMICRO Networks

Why Are Flash Disks Sometimes Slower than RAM Based Solid State Disks?

There is a performance overlap in commercially available SSD products where either flash or RAM based technology can be used and where datacenter users (who aren't affected by high vibration or military temperature environments) can choose either technology to accelerate server applications and get similar results. Intrinsically the fastest flash disks are about 5 times slower than the fastest RAM based SSDs (comparing peak IOPS). But the fastest flash disks are also faster than the slowest RAM based SSDs. The specification of the device you buy is more important than the intrinsic technology. And benchmarking is more important than theory. But the explanation below may interest some readers.

The data read cycle in a flash memory has a similar read access time to DRAM. But the write cycle takes upto 2 orders of magnitude longer. Despite that a flash disk write cycle is still much faster than a random write on the fastest hard disk drive. Flash writes involve blocks of memory cells. This can offset the intrinsic slowness of flash writes if writes to the flash disk involve contiguous addresses - because the write time for the block is the same as for a single word. There are internal housekeeping functions within fast flash disks which transparently manage all this optimization. In the fastest flash disks the write access time is also accelerated by internal RAM caching. The true nature of the flash write cycle only affects applications which perform sustained high speed writes - such as real-time data acquisition. In these applications the sustained write performance is more important than the peak burst rate quoted on the data sheet. Most business applications involve random reads and writes, with more reads than writes, and the peak I/O rates quoted by flash manufacturers are likely to be consistent with the performance achieved. See also:- article:- Flash Solid State Disks - Inferior Technology or Closet Superstar?

SiliconDrive PC Cards from from SiliconSystems

SiliconDrive PC Card Solid State
Disks - from SiliconSystems

1U rackmount Solid State SAN from Curtis

1U rackmount FC Solid State Disk
from Curtis

Solid State Disks on Cards by Bus Type
Only 17.2% of SSD users said that a computer bus interface or host bus adapter format suited their requirements. PCMCIA, SD and other consumer Flash Memory cards have capacities which overlap with low end SSDs, but they are too slow for most SSD applications.
chip / PCB module	PCI	compactPCI	PMC	VMEbus
Afaya BiTMICRO Networks M-Systems SanDisk Silicon Storage Technology SiliconSystems	BiTMICRO Networks Cenatek Micro Memory Taejin Infotech	Adtron Asine BiTMICRO Networks Targa Systems Division Vanguard Rugged Storage	Asine BiTMICRO Networks Vanguard Rugged Storage	Asine BiTMICRO Networks Targa Systems Division Vanguard Rugged Storage

The world's first PMC SSD was announced by BiTMICRO Networks.

The E-Disk PMC is intended for use as a boot and/or storage device for carrier boards such as CompactPCI, VME and MultiBus, and almost any other type of SBC and blade with a PMC slot. The solid-state storage mezzanine card delivers cost effective mass storage, eliminates cables and the need to use SCSI-based storage solutions for applications requiring moderate storage capacities.

E-Disk PMC also comes in rugged industrial temperature, conformally coated and conduction cooled versions. They boast I/O rates of up to 18,000 IOPS, burst read/write rates of up to 66 MB/sec, sustained random read/write rates of up to 28 MB/sec, and capacities of up to 10GB.

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DiskOnChip® - flash solid state disks
upto 2G bytes from M-Systems

How Do Solid State Disks Make Economic Sense? - When Some 3.5" Drives Cost $20,000 or More?

If your application is speeding up an enterprise server with thousands or tens of thousands of networked users then it's a mistake to think of the SSD as replacing storage. In fact the SSD is replacing servers and software licenses. SSDs can be used either to speed up the response time of existing applications as an alternative to buying more servers, or to reduce the number of servers and software licenses deployed. The economics can be compellingly in favor of an SSD deployment and are discussed in our case study articles.

Another server use for SSDs is to prolong the life of server architectures which have been end-of-lifed such as HP's Alpha. The SSD can work like a processor speedup and buy the owners more years of useful life while they evaluate viable alternatives. See the article:- Out of the Alpha Frying Pan into the Sun Fire?

Are there Applications Which are Unsuitable for Flash Disks?

Flash Disks have an intrinsic wear out mechanism which is related to the number of data writes to a specific location. In most applications such as databases and email this may take 10 to 20 years to take effect, and is unimportant compared to the life of the server. Housekeeping functions within flash disks track and map wear-out and the effect - if any - is a gradual reduction in usable capacity rather than actual data corruption. But in commercial server applications which may have an unusually high ratio of write to read cycles - such as algorithm development, signal processing research and pure mathematical research - flash should be avoided.

What New Technoogies Might Affect Solid State Disks?

The two main technologies used in SSDs today - Flash and battery backed RAM - have been proven for over a decade and hold the promise of decreasing cost and increasing capacity in line with Moore's Law. But in a 5 year timeframe there are 3 other technologies which may become commercially viable in the SSD market space.

FRAM (ferroelectric random access memory):- invented by Ramtron was first shipped in 1992 and with over 100 million devices shipped is an established non volatile memory technology which has much faster write speeds than flash and much greater endurance (typically 10 billion write cycles, compared to 1 million writes for flash). However, current FRAM products offer approximately 1,000 times less capacity than either DRAM or flash. See also:- FRAM Technology Backgrounder (pdf).

LCD storage technology:- A company called Dataslide has been working on technology which uses LCD technology which it claims will offer faster access times than current hard drives. In a paper distributed Q4 2004 the company claimed to have working prototypes which offer the equivalent of 72,000 RPM performance (4 times faster than the fastest hard drives today) and says that their technology is scalable to 12 million RPM using current materials. If true that would impact SSDs in non ruggedized server applications. But the company has yet to ship any commercial products.

MRAM (Magnetoresistive random access memory):- patented by NVE has been licensed to several semiconductor companies. Freescale, a Motorola spin-off, started sampling a 4M bit device in Q3 2004. Cypress Semiconductor offers a 256k bit device.

Warnings from History! - Non Volatile Technologies which Didn't Survive

in the late 1970s - silicon nitride EAROMs (electrically alterable ROMs) were marketed by a company called General Instruments. Unfortunately after about 3 years - it became clear that the extrapolated data life of 10 years wouldn't be achieved in practise. As a result this product was dropped by users and didn't survive in the market.

in the early 1980s - Intel's 1M bit bubble memory created a lot excitement as a new non volatile solid state memory technology. Intel shipped design kits and boards to developers using this technology. But it failed to be scalable or cost effective. Intel spun off the magnetic division in 1987 to Memtech (who now make flash SSDs) but bubble memory dropped into oblivion.

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