Considering Solid-State Disks For Your Data Storage Environment
Posted on Thu, Jul 22, 2010 @ 09:55 AM
Solid-state disks (SSD) are the next major step forward in storage technology. Think of the SSD as you would the more familiar flash drive (memory stick), but in a conventional disk drive form factor. However, even though an SSD might look physically similar to a conventional hard disk drive, the SSD does not employ spinning metal disks at all. Rather, the SSD utilizes erasable, writeable, cell-based memory chips that can store data reliably even when they’re powered off. You may see the acronym NAND used in descriptions of SSD technology [NAND = Not AND (electronic logic gate)].
Vastly improved reliability and performance are the main attractions to SSD technology. When looking at the two images below, take note that unlike the conventional disk drive on the left, the SSD has no moving parts — this is the major reason for the increased reliability offered by SSD technology.
A Little History
I remember back in the early 1980s when the company I was working for bought their first server… for approximately $10K. About half of the cost of that server was spent on the single, internal 1-GB hard disk drive (no that is not a typo, 1 GB!). It was a 5.25” form factor, full-height SCSI disk drive — which is beastly by today’s standards — and my colleagues and I wondered if we would ever use all of that space.
Of course the ubiquitous, magnetic hard disk drive has come a long way since the early days of 10-MB, 20-MB and 40-MB personal computer disk drives, which typically used the RLL (Run Length Limited) and MFM (Modified Frequency Modulation) encoding schemes that are completely foreign to most computer professionals today.
These seemingly humble beginnings, and the ever-present requirement for increased drive performance and capacity, have brought us to the comparatively astonishing hard disk drive capacities, performance, reliability and small physical size of modern storage devices. Consider for a moment that quite a few people are walking around with literally gigabytes of music, video and pictures in their pockets stored on devices that fit in the palm of their hands! Lend further consideration to the fact that many of these storage devices are not magnetic hard disk drives, but rather chips or SSDs.
Sidebar: Does anyone remember watching an old episode of the original Star Trek television show where Spock inserted a small rectangular piece of metal into his computer console, and the object was apparently a storage device with no moving parts that contained an enormous amount of data? Well guess what folks — we’re pretty much there!
Current State of Enterprise-Class Disk Storage
In the enterprise, the currently available magnetic hard disk drives are offered with FC (Fibre-Channel), SATA (Serial Advanced Technology Attachment) and SAS (Serial Attached SCSI) connectivity. Older IDE (Integrated Drive Electronics) and ATA (Advanced Technology Attachment) technology can still be found in PCs, and conventional SCSI has pretty much been superseded by SAS.
There is a variation available from a couple of manufacturers that mates an ATA drive with FC connectivity, and this is referred to as FATA. This variation in drive type and connectivity speaks to striking the balance between drive performance, reliability and cost, and is predominately described using the Storage Tier Model.
Tier 1 is described as the highest performance, most reliable and consequently most expensive storage tier. Tiers 2 and 3 take steps down in performance and reliability, thus lowering drive cost. The savings can be significant, so it is worth making the effort to categorize data into the storage tier model.
Generally, an organization’s most critical and most frequently accessed data will reside on Tier 1 storage devices. Data that is static, infrequently accessed or judged non-critical to daily operations is generally stored on Tier 2 or Tier 3 storage devices. Software is available to assist in the automation of this ongoing categorization of data.
Solid State Disk Storage in the Enterprise
So what about the potential of using newer SSDs for enterprise-class storage requirements, and where do they fit in the storage tier model? For some time now, SSDs could only be found on the periphery of the storage market, serving those who needed significantly more performance than was available in conventional magnetic hard disk drives. (Demanding streaming video applications is one such usage that comes to mind.)
The issue with SSD technology to date has been the storage density-to-cost ratio. In other words, SSD technology is quite expensive as compared to conventional spinning disks. This is changing, although slower than many would like. In fact, SSD drives of reasonable size (100GB+) can be found as options in high-end notebook computers from several popular vendors.
SSD in a MacBook Air
When considering enterprise storage, many people use a cost-per-GB or cost-per-TB equation to make purchase desicions. As of this writing we are just on the verge of being able to justify the cost of SSD technology in enterprise-class servers based upon IOPS (Input/Output Operations Per Second) performance.
Consider that the typical, conventional enterprise-class hard disk drive can deliver roughly 150 to 300 IOPS, compared to SSDs that can deliver approximately 100,000 IOPS, and you begin to realize how some quick math can justify the cost differential for those mission-critical applications wherein a time advantage translates immediately into a business advantage. An example would be the healthcare or financial industries.
The writing is clearly on the wall — as the capacity-to-cost ratio of SSDs continues to get closer to that of conventional hard disk drives, buyers will certainly invest in the newer, faster and more reliable technology. As you may have already surmised, this transition is expected to happen at the Tier 1 storage level first, and it may take significantly longer for SSDs to make their way into the Tier 2 or 3 levels of the storage hierarchy where cost is the paramount consideration.
It is also worth mentioning that adopting SSDs is not simply a matter of swapping out existing hard disks for the new SSDs. New controllers and other electronics are required, and consequently SSDs will more than likely find their way into enterprise environments as part of a larger purchase, such as a storage array, a server or a specialty appliance.
The Advice
If you have not already implemented, or lent consideration to, storage-tiering solutions, you should soon. Why? For most businesses and organizations (and yes, even individuals!), data continues to grow at an unrelenting pace.
One reason is that significantly more transactions are done electronically versus on paper these days. For example: Medical records are now stored electronically, and radiology images are many and large in size (and are also stored electronically). Old paper documents are being converted and stored. Even email has become a mission-critical application in many business environments where it wasn’t just a few years ago, and it presents many storage challenges. Corporate databases are growing in number and size.
We could go on and on, but the point is made that storage needs are continuing to increase, and therefore we would be wise to get a handle on the management of all of this data.
Implementation of a storage management, or tiering, solution now can prepare you for the consideration of implementing SSD storage in the future for your Tier 1 or mission-critical requirements when the time is right. Consequently, it will be much easier to justify the cost if you can demonstrate that you have the data storage environment reasonably under control. Rest assured, adopting a storage management policy and getting ready for SSD in your environment is worthy of your time because technology moves fast, and SSD will be pervasive in the enterprise in just a few years. Are you ready?
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Perry Szarka is a Solution Consultant at MCPc with expertise in data storage and network infrastructure. He works closely with clients to understand their business objectives and discover solutions to help them achieve their goals.
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