Flash vs. Platters

Solid state drives offer a tantalizing glimpse at the future of enterprise storage. But one glaring shortcoming -- beyond price and capacity -- is holding them back.

The humble hard disk drive (HDD) has served the storage needs of consumer grade desktops, workstations, and servers quite well over the past 15 years, with their basic design dating back even further. Quick access to information allowed for productivity gains even with the routine floppy shuffle early on.

Like any technology, its solid run as main data storage platform has taken a few hits here and there. However, with the adoption of portable computers as a modern day workhorse, some flaws have become glaringly evident.

Despite the rare, highly publicized batch failures and early design issues, drives have been as reliable as one could expect given their operating environment.

Its Achilles' heel has been its somewhat fragile collection of components, all placed within close proximity of some very fast spinning platters that just happen to store your valuable information. An unfortunate sudden deceleration is enough to cause a few choice words to slip and plenty of lamenting to follow.

This exact scenario has played out countless times for mobile computer users and anyone unlucky enough to drop their drive-based digital media player. As everyone can attest, they'd rather have the data stored on the device back than the drive itself, and at minimum cost. Given the pricing on professional data recovery, this usually isn't economically feasible.

There hasn't been much in the way of protection for these drives aside from some shock absorption and accelerometer applications that "sense" a fall and take measures to lock down a drive before its fateful hit. A few good stopgaps, but a sudden impact from any angle is still cause for concern.

Swapping in the Silicon

Drive manufacturers have made recent moves to include a sizable chunk of flash memory into their products. These Hybrid Hard Disk Drives promise lower power consumption and improved reliability by shutting down the platters of your drive until the flash memory portion is close to reaching its storage capacity, at which point it will spin up and save your newly created information.

It sounds like a good compromise but early versions of these drives sport pitifully small amounts of flash memory that a few file duplication operations can quickly overwhelm. In fact, early tests haven't exhibited the improvements that some of its backers tout.

SanDisk 64GB SSDThis all leads us to the Solid State Drive.

The current trend is to mount several flash chips inside of an enclosure -- roughly the size of an HDD -- with the assorted control and interface chips that allow it to plug seamlessly into your standard storage connections. It's a blindingly obvious solution that has solved many storage issues, and introduced a few of its own.

The lack of moving parts is one of the most sought after aspects. Noiseless operation and the simple fact that it makes an accidental drop a bit less of a concern for users offer that always-welcome peace of mind.

Power consumption is another key area where these drives are showing improvements over older technology - great news for mobile users and the green crowd. With power consumption rates as low as 2 watts during operation, SSDs offer power savings of up to 75% compared to standard desktop hard disk drives, with even larger savings compared to high performance models.

Other key aspects are superior performance in most drive operations as Mtron's latest line has been demonstrating. Consistent read/write performance, comparable to high end desktop drives such as the Western Digital Raptor, shows the newest models hitting 94MB/s read rates and maintaining a 74MB/s write rate throughout.

SSDs even seem capable of scaling much better in some RAID configurations.

It should be noted, however, that most current SSDs are limited in size to the dozens of gigabytes range with only a few of the planned boutique models hitting the high hundreds of GBs later this year.

The Hidden Flaw

Each and every flash chip you own has a finite number of write cycles per memory block that can eventually render a particular portion of its memory useless. Engineers have employed plenty of techniques to extend a flash chip's longevity through wear leveling so you're not likely to see the effects on your digital camera or thumb drive but it's a whole different story with computers.

Your operating system and applications are thrashing along with a swap file and a log file here or there, which along with their precious cache files creates situations where data has to be frequently saved to a drive. Consumer electronics aren't likely to encounter these conditions that would overwhelm most flash chips much more quickly.

It's quite the ugly situation and it's one that should relegate SSDs to low-write situations, such as embedded applications. But the usual push by PC manufacturers to have the latest and greatest in technology has it popping up as a very attractive option in high-end system builds despite the flaws and the current high cost of entry.

But this is all a speed bump, of course. Flash technology will continue to quickly improve on its durability and is likely to see even greater performance gains with larger capacity drives to follow.

Having said that, this generation of drives doesn't appear to be a good fit for most power users or server situations despite its performance and power saving benefits. So you may just have to make do with that old standby: the hard disk drive.

For now, at least.

This article was first published on EnterpriseITPlanet.com.

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