Storage

Solid state drive storage: Good for the enterprise?


Over the years, the good old magnetic platter has undergone many changes that have made hard drives a commodity and drastically driven down the cost of storage. Today, storage costs anywhere from about 30 cents per GB for SATA drives to $3 per GB for enterprise-grade SAS drives. Of course, this is a rough estimate that varies wildly based on drive capacity, manufacturer, RPMs, etc. For the purposes of this post, it's a close enough estimate.

Recently, however, a relatively new contender - the solid state drive (SSD) - has emerged in the storage game that could, over time, seriously shake up the storage market. Although solid state storage has been around for a while in the form of USB-powered flash drives, the technology is evolving to a point where SSDs can, in some cases, start to supplant traditional storage. However, solid state storage is very different from traditional storage in a number of ways.

Unlike their mechanical counterparts, solid state drives have no moving parts. Instead, a solid state storage device uses either volatile or non-volatile memory to achieve its storage capabilities. Units that use DRAM-based technology (volatile memory) basically have a bank of RAM installed that takes the place of a hard drive. Since data stored in DRAM cannot survive a power loss, these kinds of devices often have backup storage that can be used in the event of a power failure. Although extremely fast, this kind of storage is not adequate for general storage in the enterprise.

SSDs become acceptable in some situations in the enterprise when the disks are built using non-volatile flash memory. Although slower than DRAM-based SSDs, flash-based SSDs do not require battery backup and provide much more reliability -- mainly since the stored data can survive a power failure.

Until recently, SSDs were not cost-effective replacements for traditional hard drives. With a current approximate price tag of $10 - $20 per GB for SSD-based storage, it isn't going to immediately supplant magnetic hard drives for most organizations. And, in the data center, SSDs are probably a very long way off. Once the price of SSD-based storage comes down to the high end of SAS, you will likely see more manufacturers creating enterprise-grade storage arrays based on flash.

In the meantime, however, there has been significant interest in SSDs for mobile devices. Even though SSD-based storage is more expensive, with lower power consumption, lower levels of heat, and similar (if not better) performance, putting SSDs into a laptop or other mobile device makes a lot of sense.

Solid state drive disadvantages

Besides the price, SSDs do have some disadvantages when compared with traditional magnetic media, although some of these downsides have been mitigated.

First, flash-based storage device blocks (each flash device is broken into blocks) have a limited number of write cycles before they wear out. Older flash controllers did not do a good job managing the location of written files, so some blocks of the flash device might be used over and over while other blocks remain completely untouched for the life of the device, thus limiting the device's potential lifespan. Newer controllers do a much better job of managing write locations so as to maximize the life of the disk. In fact, with the optimal write method and usage pattern, a flash device can even outlive a magnetic disk.

Second, SSD capacity remains much lower than that provided by magnetic media and will for some time. Although there are 160GB SSDs out there, compare that to the recent announcement of 1TB magnetic hard drives.  When it comes to raw storage, magnetic media can't be touched yet.

Another major downside to flash-based devices is the difficulty of data recovery.  Often, when a flash drive fails, it's done. End of story. With magnetic disks, there are tried and true methods to try to recover information. (Have you ever put a hard drive into a freezer? It works.) Although information can sometimes be recovered from a flash device, it's much harder and much less of a certainty.

Finally, although solid state drives shine when used with random I/O, they do not do as well as magnetic media when it comes to sequential I/O.

Summary

For the enterprise, SSDs will be limited to portable devices and low capacity requirements until two things happen: (1) The price per GB drops significantly, and (2) the device capacity increases significantly. Once those two things happen, the fight will be on.

About

Since 1994, Scott Lowe has been providing technology solutions to a variety of organizations. After spending 10 years in multiple CIO roles, Scott is now an independent consultant, blogger, author, owner of The 1610 Group, and a Senior IT Executive w...

7 comments
gordonmcke
gordonmcke

Scott: Thanks for another interesting article. This reminds me of the old adage my grandmother used: "Everything old will be new again." I sold SSD on mainframes in the 1980s before IBM introduced XA and recaptured that market. Now I see it poised to offer good service in the open systems arena. Why? Because virtualization is beginning to chew up server memory and systems which only single applications are now being required to service entire enterprises and multiple applications. Add in the increased I/O required for video streaming and you have a reciepe for bottlenecks. One thing will need to happen, IMHO, for SSD to take off. Storage and application vendors are going to have to design software that can take advantage of tiered storage. Microsoft, for example, could design SQL database programs so that they make better use of high performance disk for transaction logging, for example. In the intellegent storage vendors, Compellent Technologies has designed a program called Dynamic Block Architecture which allows their SAN product to automatically identify data blocks with high performance requirements and move those blocks to "Tier 1" (SSD) storage. These types of intellegence will allow clients to get the best bang for the buck for expensive SSD storage. Gordon McKemie Ohio Valley Storage Consultants Anchorage, Kentucky

Die Ubermensch
Die Ubermensch

Everthing old is new again! I recall in the 1980's several companies making solid state disk devices for mainframes. Very high performance and great for all the temporary storage used by the operating system.

1dennis3
1dennis3

I agree completly. SSD flash drive are very handy for small very portable storage, but have a limited life span. I found out the hard way that they will not hold up to heavy daily use. When they reach their end of life, they just die and anything and everything on them is gone. But for storage with occasional use, they are great. SSD in a size that matches magnetic is a ways off yet, but they are making steps that way. A 1 terabyte flash drive, now that would be nice!

shamanbobx
shamanbobx

That would be outrageous! But, for just a few seconds after absorbing the coment though I had a few images "flash" through my mind's eye. > The first was some guy searching a workstation for an open USB port to plug in his 1TB flash drive which sits on the floor behind him and looks like a welding cart! hahaha > The second image was of some poor sucker getting that familiar pop-up that estimates the approx. time remaining to complete a requested operation. Just after they requested that the system transfer anything close to 1TB of data. > 486:23:17 time remaining...

ryanray
ryanray

that was too funny. Im thinking along the lines of volumes/partitions or something similar.

anurag.aggarwal
anurag.aggarwal

SSD is in use in form of Flash pen drives. But when it had increased capacity it can be deployed in Laptops making them really robust, probably lighter and reliable also. This is indeed going to last. No Moving part !!

shamanbobx
shamanbobx

I read an article a short while back that told about some the major manufacturers of portable computers doing fesability tests involving SSD's being used to replace all or part of the storage needs in their products. One of the companies (name withheld to protect... well... to protect ME!) made comment that "The systems equiped with SSD drives withstood amazing amounts of physical abuse." and that "Some of the test system's were subjected to abuse that rendered the system itself permanently inopperable. While the SSD storage remained undamaged and usable once removed from the wreakage." Now that is one aspect that is quite interesting. Especially when, according to statistics, the typical HDD continues to be one of the major weak points in the portable pc design. They (HDD's) being prone to sudden catastrophic failure from physical shock sustained during typical everyday use. Let's face it, the systems themselves are "usually" portable, as the name implies. But magnetic disk drives were never really designed for the portable lifestyle. One good jarring at the wrong moment (while the disk is actively reading/writing mainly) and there is a good chance that permanent damage is done.

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