With predictable regularity someone surfaces on the Web, claiming they have discovered a way to turn slow SATA arrays into high performance storage. Their method usually involves adding complex and sophisticated software to reallocate and optimize system resources. While there may a few circumstances where this might work, in reality it is usually just the opposite.
The problem with this concept is similar to the kit car world several decades ago. At the time, kit-build sports cars were all the rage. Automobile enthusiasts were intrigued by the idea of building a phenomenal sports car by mounting a sleek fiberglass body on the chassis of a humble Volkswagen Beetle. Done properly, the results were amazing! As long as their workmanship was good, the end results would rival the appearance of a Ferrari, Ford GT-40, or Lamborghini!
However, this grand illusion disappeared the minute its proud owner started the engine. Despite its stunning appearance, the kit car was still built on top of an anemic VW bug chassis, power train, and suspension!
Today we see a similar illusion being promoted by vendors claiming to offer “commodity storage” capable of delivering the same high performance as complex SAN and NAS systems. Overly enthusiastic suppliers push the virtues of cheap “commodity” storage arrays with amazing capabilities as a differentiator in this highly competitive market. The myth is perpetuated within the industry by a general lack of understanding of the underlying disk technology characteristics, and a desperate need to manage shrinking IT budgets, coupled with a growing demand for storage capacity.
According to this technical fantasy, underlying hardware limitations don’t count. In theory, if you simply run a bunch of complex software functions on the storage array controllers, you somehow repeal the laws of physics and get “something for nothing”.
That sounds appealing, but it unfortunately just doesn’t work that way. Like the kit car’s Achilles heel, hardware limitations of underlying disk technology govern the array’s capabilities, throughput, reliability, scalability, and price.
• Drive Latencies – the inherent latency incurred to move read/write heads and rotate disks until the appropriate sector address is available can vary significantly.
For example, comparing performance of a 300GB, 15K RPM SAS disk to a 3TB 7200 RPM SATA disk produces the following results:
• Controller Overhead – Masking SATA performance by adding processor capabilities may not be the answer either. Call it what you will – Controller, SP, NAS head, or something else. A storage controller is simply a dedicated server performing specialized storage operations. This means controllers can become overburdened by loading multiple sophisticated applications on them. More complex processes also means the controller consumes additional internal resources (memory, bandwidth, cache, I/O queues, etc.). As real-time capabilities like thin provisioning, automated tiering, deduplication and data compression applications are added, the array’s throughput will diminish.
• “Magic” Cache – This is another area where lots of smoke-and-mirrors can be found. Regardless of the marketing hype, cache is still governed by the laws of physics and has predictable characteristics. If you put a large amounts of cache in front of slow SATA disk, your systems will run really fast – as long as requested data is already located in cache. When it isn’t you must go out to slow SATA disk and utilize the same data retrieval process as every disk access. The same is true when cache is periodically flushed to disk to protect data integrity. Cache is a great tool that can significantly enhance the performance of a storage array. However, it is expensive, and will never act as a “black box” that somehow makes slow SATA disk perform like 15K RPM SAS disks.
• Other Differences – Additional differentiators between “commodity storage” and high performance storage include available I/Os per second, disk latency, RAID level selected, IOPS per GB capability, MTBF reliability, and the Bit Error Rate.
When citing the benefits of “tricked out” commodity storage, champions of this approach usually point to obscure white papers written by social media providers, universities, and research labs. These may serve as interesting reading, but seldom have much in common with production IT operations and “the real world”. Most Universities and research labs struggle with restricted funding, and must turn to highly creative (and sometimes unusual) methods to achieve specific functions from a less-than-optimal equipment. Large social media providers seldom suffer from budget constraints, but create non-standard solutions to meet highly specialized, stable, and predictable user scenarios. This may illustrate an interesting use of technology, but have little value for mainstream IT operations.
As with most things in life, “you can’t get something for nothing”, and the idea of somehow enhancing commodity storage to meet all enterprise data requirements is no exception.
Like most other things, technology suffers from advancing age. That leading-edge wonder of just a few years ago is today’s mainstream system. This aging process creates great headaches for IT departments, who constantly see “the bar” being moved upward. Just when it seems like the computing environment is under control, equipment needs to be updated.
Unless a company is well disciplined in enforcing their technical refresh cycle, the aging process can also lure some organizations into a trap. The thinking goes something like this – “Why not put off a technology update by a year or two? Budgets are tight, the IT staff is overworked, and things seem to be going along just fine.” It makes sense, doesn’t it?
Well, not exactly. If you look beyond the purchase and migration expenses, there are other major cost factors to consider.
Power Reduction: There have been major changes in storage device energy efficiency over the past decade. Five years ago the 300GB, 15K RPM 3.5-inch drive was leading-edge technology. Today, that has disk been superseded by 2.5-inch disks of the same speed and capacity. Other than its physical size, other major changes are the disk’s interface (33% faster than Fibre Channel) and its power consumption (about 70% less than a 3.5-inch drive). For 100TB of raw storage, $3577 per year could be saved by reduced power consumption alone.
Cooling Cost Reduction: A by-product of converting energy to power is heat, and systems used to eliminate heat consume power too. The following chart compares the cost for cooling 100TB of 3.5-inch disks with the same capacity provided by 2.5-disks. Using 2.5-inch disks, cooling costs could be reduced by $3548 per year, per 100TB of storage.
Floor Space Reduction: Another significant data center cost is for floor space. This expense can vary widely, depending on the type resources provided and level of high availability guaranteed by the Service Level Agreement. For the purpose of cost comparison, we’ll take a fairly conservative $9600 per equipment rack per year. We will also assume fractional amounts are available, although in the real world full rack pricing might be required. Given the higher density provided by 2.5-inch disks, a cost savings of $9,371 would be achieved.
In the example above, simply replacing aging 300GB, 15K RPM 3.5-inch FC disk drives with the latest 300GB, 15K RPM 2.5-inch FC disk drives will yield the following operational costs (OPEX) savings:
Reduced power $ 3,577
Reduced cooling $ 3,548
Less floor space $ 9,371
Total Savings $ 16,496 per 100TB of storage
Over a storage array’s standard 5-year service cycle, OPEX savings could result in as much as $82K dollars or more.
Addition benefits from a storage refresh might also include tiering storage (typically yielding around a 30% savings over non-tiered storage), reduced support contract costs, and less time spent managing older, more labor-intensive storage subsystems. There is also an opportunity for capital expense (CAPEX) savings by cleverly designing cost-optimized equipment, but that’s a story for a future article.
Don’t be misled into thinking that a delay of your storage technical refresh cycle will save money. In the end it could be a very costly decision.
Blade servers, virtualization, solid state disks, and 16Gbps fibre channel – it’s challenging to keep up with today’s advanced technology. The complexity and sophistication of emerging products can be dizzying. In most cases we’ve learned how to cope with these changes, but there are a few areas where we still cling to vestiges of the past. One of these relics of past decades is the impenetrable, monolithic data center.
The data center traces its roots back to the mainframe, when all computing resources were housed in a single, highly specialized facility designed specifically to support processing operations. Since there was little or no effort to classify data, these bastions of data processing were over-designed to ensure the most critical requirements were supported. This model was well-suited for mainframes and centralized computing, but it falls well short of meeting the needs of our modern IT environments.
Traditional data center facilities provide a one-size-fits-all solution. At an average $700 to $1500 per square foot, they are expensive to build. They lack the scalability and flexibility to respond to dynamic market changes and shifts in technology. Since these require massive investments of capital, they must be built not only to contain today’s IT equipment, but also satisfy growth requirements for 25-years or more. The end result is a tremendous waste of capacity, corporate funds tied up for decades, making assumptions about the direction and needs of future IT technology, the build-out of a one-size-fits-all facility, and a price tag that makes disaster recovery redundancy well beyond the reach of most companies.
An excellent solution to this problem is already a proven technology – the Portable Modular Data Center. These are typically self-contained data center modules that contain a comprehensive set of power, cooling, security, and internal infrastructure to support a dozen or more equipment racks per module with up to 30kW of power per rack. These units are relatively inexpensive, highly scalable, simple to deploy, energy efficient (Green), and factory constructed to ensure consistent quality and reproducible technology. As modules, they can be deployed incrementally as requirements dictate, avoiding major one-time capital expenditures for facilities.
Their inherent modularity and scalability make them an excellent choice for incrementally building out finely-tuned disaster recovery facilities. Here is an example of how modular data centers can be leveraged to cost-effectively provide Disaster Recovery protection of an organization’s data assets.
- Mission Critical Operations (typically 10% to 15%)
These are applications and data that might severely cripple the organization if they were not available for any significant period of time.
Strategy – Deploy synchronous replication technology to maintain an up-to-date mirror image of the data that could be brought to operational status within a matter of minutes.
Solution – Deploy one or more Portable Module Data Center units within 30-miles (to minimize latency) and run synchronous replication between the primary data center and the modular facility. Since 20-30 miles of separation would protect from a local disaster, but not a region-wide event, it might be worthwhile to replicate asynchronously from the modular data center to some remote (out-of-region) location. A small amount of data might be lost in the event of a disaster (due to asynchronous delay), but processing could still be brought back on-line quickly with minimal loss of data and only a limited interruption to operations.
- Vital Operations (typically 20% to 25%)
These applications and data are very important to the organization, but an outage of several hours would not financially cripple the business.
Strategy – Deploy an asynchronous replication mechanism outside the region to ensure an almost-up-to-date copy of data is available for rapid recovery.
Solution – Deploy one or more Portable Module Data Center units anywhere in the country and run asynchronous replication between the primary data center and the remote modular facility. Since distance is not a limiting factor for asynchronous replication, the modular facility could be installed anywhere. This protects from disasters occurring not only locally, but within the region as well. A small amount of data might be lost in the event of a disaster (due to asynchronous delay), but applications and databases could still be recovered quickly with minimal loss of data and only a limited interruption to operations.
- Sensitive Operations (typically 20% to 30%)
These applications and data are important to the organization, but an outage of several days to one week would have only a negligible financial impact on the business.
Strategy – (same as above) Use the same asynchronous replication mechanism outside the region to ensure an almost-up-to-date copy of data is available for rapid recovery.
Solution – Add one or more Portable Module Data Center units to the above facility (as required) and run asynchronous replication between the primary data center and the remote modular facility.
- Non-Critical Operations (typically 40% or more)These applications and data are incidental to the organization and can be recovered when time is available. An outage of several weeks would have little impact on the business.
Strategy – (same as above) Use the same asynchronous replication mechanism outside the region to ensure an almost-up-to-date copy of data is available for rapid recovery.
Solution – Deploy one or more Portable Module Data Center units anywhere in the country and run asynchronous replication between the primary data center and a remote modular facility.
Note: Since non-critical applications and data tend to be passive, non-critical operations might also be a viable candidate for transitioning to an Infrastructure-as-a-Service (IaaS) provider.
Modular Data Centers are the obvious enabler for the above Disaster Recovery strategy. They allow you to deploy only the data center resource you need, when you need it. They are less expensive than either leased or build facilities, and can be scaled as required by the business.
It’s time for the IT industry to abandon their outdated concepts of what a data center should be and focus on what is needed by each class of data. The day of raised-floor mainframe “bunkers” has passed. It’s time to start managing data center resource deployment as carefully as we manage server and storage deployment. Portable Modular Data Centers allow you to implement efficient, cost-effective IT production facilities in a logical sequence, without breaking the bank in the process.
For the past several years the business community and IT industry has been buzzing about “Big Data”. The Holy Grail of business is to become a “data driven Enterprise” by efficiently mining vast amounts of internal and external data. Identifying unforeseen relationships is considered to be an excellent method to drive sales growth and extend a company’s market share. While there may be value in this approach, “Big Data” analysis will only be as successful as the value of the stored content it examines.
Since the beginning of the computer industry, organizations have collected and stored amounts of information well beyond what the law requires. Management in general holds the belief that legacy data may contain vast treasure troves of unidentified residual value. In some cases it has been justified, since an ability to recall and examine historical content has proven to identify valuable relationships. However, in some situations it is questionable just how significant the recently discovered patterns and associations may be.
Recently a new wave of analytical tools and data structures has emerged to capitalize on the growing pool of stored data. They provide new capabilities to combine and analyze dissimilar information, produce associations between obscure facts, and allow vast quantities of data to be inspected for unexpected relationships. The application of these tools provides new methods for analyzing customer needs, trends, and buying patterns.
While some of retained data may yield valuable insight into an organization’s market, expecting everything in the archive to hold such nuggets can be unrealistic, problematic, and prohibitively expensive to maintain.
Changing Customer Priorities – Today’s markets are highly dynamic, with major change occurring randomly on frequent basis. Much of the captured information has a finite shelf life. Over time customers experience life changing events, families mature and disburse, personal finances may improve or decline, and individual priorities shift. Critical buying patterns of a decade ago may have little relevance in today’s market.
The Impact of External Events – Recent political, economic, and natural phenomena have re-shaped our society. Dramatic changes in our travel patterns occurred after 9/11. Hurricane Katrina, along with the Indonesia and Japanese tsunamis effected our thinking about preparations for natural disasters. Senseless killings at a theater in Aurora CO, a shopping mall in Tucson AZ, and a Sikh Temple in Milwaukee WI make us reconsider our attendance at social events and modify entertainment plans. The impact of a protracted global recession negatively impacts spending trends, financial investments, retirement plans, and even our expectations for our future. Key indicators of a decade ago may provide marginal value today.
Attrition of Value – Another issue with analyzing vast quantities of stored legacy data is the problem of long-term retention of content with questionable business value. All data is not created equal! Details about receivables may hold a level of value for many years, while a file about last week’s cafeteria specials is almost worthless by the following week. A good example this is a management PowerPoint sent to all employees. The original copy may retain its importance for an extended period of time, but dozens of identical copies kept in user accounts provide little incremental value.
Content Duplication –In any given SAN it is typical to find several outdated copies of the same data, abandon “clone” files once needed for testing, data with expired business value, unnecessary copies of temp files, orphaned directories from departed users, and residue left from ancient applications and databases. Unless a continuous process is in place to preen and update active storage, licensing costs for “Big Data” analytical tools and systems may be prohibitive. Even if the IT budget can absorb the cost, performance will suffer from having to load, filter, and index huge quantities of irrelevant data.
While valuable insight may be gained from customer content buried deep within an organization’s data repository, due diligence should be performed on existing content to verify its value and uniqueness. The old saying “garbage in-garbage out” is just as valid in today’s “Big Data” world as it was in the heyday of the mainframe.
Traditional brick and mortar datacenters have been a mainstay of enterprise computing since the day of the mainframe. IT systems were kept in isolation in windowless, highly secure facilities that provided a constant temperature and humidity environment on a 7×24 basis. Although the cost of building new datacenters continues to increase substantially, until now relatively few options have been available.
However, with the development of the portable modular datacenter, the day of the traditional datacenter may be coming to an end. While there are several variations on the market, the most promising appears to be the completely built out facility. New datacenter modules are built from ISO standard shipping containers. They incorporate chillers, power and communications buses, forced air cooling, equipment racks, and all other components necessary for a modern datacenter. These units can be trucked to any location, moved into position on a concrete pad, connected to external resources, and be ready for systems build-out on short notice. They can be configured to operate as a singular unit, multiple units, and even as stacked arrays of modular datacenter units.
In addition to serving as a modular replacement for traditional brick-and-mortar datacenter s, there are other possibilities for Portable Modular Datacenter s:
RAPID DEPLOYMENT MODULES – For situations where rapid implementation is a key driver, or when companies simply can’t wait the 18-24 months for a new datacenter build-out.
COST CONTAINMENT – Situations where minimizing the cost for building a new datacenter facility is a primary objective
DISASTER RECOVERY – A highly flexible, cost-effective IT environment that can be deployed remotely for a Disaster Recovery solution
CAPACITY-ON-DEMAND –Modular, self-contained units that permit companies to add new datacenter capacity only-as-required (Capacity-as-a-Service?)
TEMPORARY FACILITIES – Allows companies to continue to support ongoing IT operations while a permanent datacenter facility is built
SEGREGATED SYSTEMS – Enables complete isolation of specific IT operation in an otherwise shared environment (Community Cloud?)
DYNAMIC MARKETS – A solution for highly volatile markets where future capacity requirements are difficult to predict
EMERGENCY CAPACITY – Available for relatively rapid deployment when an organization’s primary datacenter runs out of floor space
SYNCRONOUS REPLICATION – Allows the implementation of a small nearby replication site within 40KM of the primary datacenter to support replication while maintaining database consistency
MOBILE SYSTEMS – A portable IT solution that could be relocated to a different region in response to changing corporate needs or an impending disaster (such as a major hurricane).
PREFABRICATED SUB-SYSTEMS – A transportable platform for high growth companies who must buy integrated sub-systems from an external vendor, rather than building the equipment themselves.
REPURPOSING OF BUILDINGS – Modular units may be installed within existing building that are sitting idle, as long as adequate resources (power and communications) are available.
Anotherbig benefit to portable mobile datacenter units is that they’re built in a factory to exact specification. As such, they benefit from repetitive manufacturing processes and ongoing quality assurance reviews. Each module features the same level of quality and reliability as its peers. This is in sharp contrast to traditional brick-and-mortar datacenters, which are normally built as one-off custom configurations.
The concept of portable mobile datacenter units is pretty clever. If there are any downsides to this technology they are not readily apparent. Although this represents a relatively new approach, it appears to be distinctly superior to what’s been done in the past. Don’t be surprised to see a new modular datacenter unit being installed on a concrete pad near you in the foreseeable future.
There’s a quiet revolution going on in large data centers. It’s not as visible or flashy as virtualization or deduplication, but at least equal in important.
As its name implies, SAN “fabric” is a dedicated network that allows servers, storage arrays, backup & recovery systems, replication devices, and other equipment to pass data between systems. Traditionally this has been comprised of 4Gbps Fibre Channel and 1Gbps Ethernet channels. However, a new family of 8Gbps and 16Gbps Fibre Channel, 6Gbps and 12Gbps SAS, and 10Gbps Ethernet are quietly replacing legacy fabric with links capable of 2 – 4 times the performance.
The following is a comparison of the maximum throughput rates of various SAN fabric links:
Performance ranges from the relatively outdated 1Gbps channel (Ethernet or FC) capable of supporting data transfers of up to 100 MB per second, to 16Gbps Fibre Channel capable of handling 1940 MB per second. Since all are capable of full duplex (bi-directional) operations, the sustainable throughput rate is actually twice the speed indicated in the chart. If these blazing new speeds are still insufficient, 10Gbps Ethernet, 12Gbps SAS, and 16Gbps Fibre Channel can be “trunked” – bundled together to produce an aggregate bandwidth equal to the number of individual channels tied together. (For example, eight 16Gbps FC channels can be bundled to create a 128Gbps “trunk”.)
In addition to high channel speeds, 10Gbps Ethernet and 16Gbps Fibre Channel both implement a 64b/66b encoding scheme, rather than the 8b/10b encoding scheme used by lower performance channels. The encoding process improves the quality of the data transmission, but at a cost. An 8b/10b encoding process decreases available bandwidth by 20%, while 64b/66b encoding only reduces bandwidth by 3.03%. This significantly increases data transfer efficiency.
While 8/16Gbps Fibre Channel and 10Gbps Ethernet are changing the game at the front-end, SAS is revolutionizing the back-end disk drive connections as well. For over a decade, enterprise-grade disks had 2Gbps or 4Gbps ports, and were attached to a Fiber Channel Arbitrated Loop (FC-AL). Like any technologies using loop technology, low traffic enjoyed maximum speed but performance dropped off as demand increased. Under heavy load conditions, the back-end bus could become a bottle-neck.
SAS will change that for two reasons. First it uses switched technology, so every device attached to the controller “owns” 100% of the bus bandwidth. The latency “dog leg pattern” found on busy FC-AL busses is eliminated. Secondly current SAS drives are shipping with 6Gbps ports, which are 50% faster than 4Gbps Fibre Channel. Just over the horizon are 12Gbps SAS speeds that will offer a 300% increase in bandwidth to the disks, and do it over switched (isolated) channels.
Recent improvements in fabric performance will support emerging SSD technology, and allow SANs to gracefully scale to support storage arrays staggering under a growth rate of 40% – 50% per year.
It’s easy to hold onto the concept that IT is all about systems, networks, and software. This has been accepted wisdom for the past 50-years. It’s a comfortable concept, but one that is increasing inaccurate and downright dangerous as we move into an era of “big data”! In today’s world not about systems, networks, applications, or the datacenter – it’s all about the data!
For decades accumulated data was treated as a simply bi-product of information processing activities. However, there is growing awareness that stored information is not just digital “raw material”, but a corporate asset containing vast amounts of innate value. Like any other high-value asset, it can be bought or sold, traded, stolen, enhanced, or destroyed.
A good analogy for today’s large-scale storage array is to that of a gold mine. Data is the nuggets of gold embedded in the mine. The storage arrays containing data are the “mine” that houses and protects resident data. Complex and sophisticated hardware, software, tools, and skill-sets are simply tools used to locate, manipulate, and extract the “gold” (data assets) from its surrounding environment. The presence of high value “nuggets” is the sole reason the mining operation exists. If there was no “gold”, the equipment used to extract and/or manipulate it would be of little value.
This presents a new paradigm. For years storage was considered some secondary peripheral that was considered only when new systems or applications were being deployed. Today storage has an identity of its own that is independent from the other systems and software in the environment.
Data is no longer just a commodity or some type of operational residue left over from the computing process. “Big Data” forces a shift in focus from IT assets deployment and administration to the management of high-value data assets. It dictates that data assets sit at the center of concentric rings, ensuring security, recoverability, accessibility, performance, data manipulation, and other aspects of data retention are addressed as abstract requirements with unique requirements. Now information must be captured, identified, valued, classified, assigned to resources, protected, managed according to policy, and ultimately purged from the system after its value to the organization has been expended.
This requires a fundamental change in corporate culture. As we move into an era of “big data” the entire organization must be aware of information’s value as an asset, and the shift from technology-centric approaches for IT management. Just like gold in the above analogy, users must recognize that all data is not “created equal” and delivers different levels of value to an organization for specific periods of time. For example, financial records typically have a high level of inherent value, and retain a level of value for some defined period of time. (The Sarbanes-Oxley act requires publicly-traded companies to maintain related audit documents for no less than seven years after the completion of an audit. Companies in violation of this can face fines of up to $10 million and prison sentences of 20 years for Executives.)
However, differences in value must be recognized and managed accordingly. Last week’s memo about the cafeteria’s luncheon specials must not be retained and managed in the same fashion as an employee’s personnel record. When entered into the system, information should be classified according to a well-defined set of guidelines. With that information it can be assigned to an appropriate storage tier, backed up on a regular schedule, kept available on active storage as necessary, later written to low-cost archiving media to meet regulatory and litigation compliance needs. Once data no longer delivers value to an organization, it can be expired by policy, freeing up expensive resources for re-use.
This approach moves IT emphasis away from building systems tactically by simply adding more-of-the-same, and replacing it with a focus on sophisticated management tools and utilities that automate the process. Clearly articulated processes and procedures must replace “tribal lore” and anecdotal knowledge for managing the data repositories of tomorrow.
“Big Data” ushers in an entirely new way of thinking about information as stored, high-value assets. It forces IT Departments to re-evaluate their approach for management of data resources on a massive scale. At a data growth rate of 35% to 50% per year, business-as-usual is no longer an option. As aptly noted in a Bob Dylan song, “the times they are a-changin”. We must adapt accordingly, or suffer the consequences.
With today’s technology there can be no status quo. As the IT industry advances, so must each organization’s efforts to embrace new equipment, applications, and approaches. Without an ongoing process of improvement, IT infrastructures progressively become outdated and the business group they support grows incrementally less effective.
In September of 2010, the INCITS T11.2 Committee ratified the standard for 16Gbps Fibre Channel, ushering in the next generation of SAN fabric. Unlike Ethernet, Fibre Channel is designed for one specific purpose – low overhead transmission of block data. While this capability may be less important for smaller requirements where convenience and simplicity are paramount, it is critical for larger datacenters where massive storage repositories must be managed, migrated, and protected. For this environment, 16Gbps offers more than twice the bandwidth of the current 8Gbps SAN and 40% more bandwidth than the recently released 10Gbps Ethernet with FCoE (Fibre Channel over Ethernet).
But is an investment in 16Gbps Fibre Channel justified? If a company has reached a point where SAN fabric is approaching saturation or SAN equipment is approaching retirement, then definitely yes! Here is how 16Gbps stacks up against both slower fibre channel implementations and with 10Gbps Ethernet.
|Port Speed||Protocol||Average HBA/NIC Price||Transfer
|Transfer Time for 1TB||Bandwidth
|LPE16002||16 Gbps||Fibre Channel||$1,808||1939 MB/sec.||1.43 Hrs.||$0.93||160%|
|OCe11102||10 Gbps||Ethernet||$1,522||1212 MB/sec.||2.29 Hrs.||$1.26||100%|
|LPe12002||8 Gbps||Fibre Channel||$1,223||800 MB/sec.||3.47 Hrs.||$1.53||65%|
|LPe11000||4 Gbps||Fibre Channel||$891||400 MB/sec.||6.94 Hrs.||$2.23||32%|
This table highlights several differences between 4/8/16 Gbps fibre channel and 10Gbps Ethernet with FCoE technology (sometimes marketed as Unified Storage). The street prices for a popular I/O Controller manufacturer clearly indicates there are relatively small differences between controller prices, particularly for the faster controllers. Although the 16Gbps HBA is 40% quicker, it is only 17% more expensive!
However, a far more important issue is that 16Gbps fibre channel is backward compatible with existing 4/8 Gbps SAN equipment. This allows segments of the SAN to be gradually upgraded to leading-edge technology without having to suffer the financial impact of legacy equipment rip-and-replace approaches.
In addition to providing a robust, purpose-built infrastructure for migrating large blocks of data, it also offers lower power consumption per port, a simplified cabling infrastructure, and the ability to “trunk” (combine) channel bandwidth up to 128Gbps! It doubles the number of ports and available bandwidth in the same 4U rack space for edge switches, providing the potential for a saving of over $3300 per edge switch.
Even more significant is that 16Gbps provides the additional performance necessary to support the next generation of storage, which will be based on 6Gbps and 12Gbps SAS disk drives. Unlike legacy FC storage, which was based upon 4Gbps FC-AL arbitrated loops, the new SAS arrays are on switched connections. Switching provides a point-to-point connection for each disk drive, ensuring every 6Gbps SAS connection (or in the near future, 12Gbps SAS connection) will have a direct connection to the SAN fabric. This eliminates backend saturation of legacy array FC-AL shared busses, and will place far greater demand for storage channel performance on the SAN fabric.
So do the benefits of 16Gbps fibre channel outweigh its modest price premium? Like many things in life – it depends! Block-based 16Gbps fibre channel SAN fabric is not for every storage requirement, but neither is file-based 10Gbps FCoE or iSCSI. If it is a departmental storage requirement or an environment where NAS or iSCSI has previously been deployed, then replacing the incumbent protocol with 16Gbps fibre channel may or may not have merit. However, large SAN storage array are particularly dependent on high performance equipment specifically designed for efficient data transfers. This is an arena where the capabilities and attributes of 16Gbps fibre channel will shine.
In any case, the best protection against making a poor choice is to thoroughly research the strengths and weaknesses of each technology and seek out professional guidance from a vendor-neutral storage expert with a Subject Matter Expert level understanding of the storage industry and its technology.
It is somewhat surprising just how many skilled IT specialists still shy away from eliminating traditional internal boot disks with a Boot-from-SAN process. I realize old habits die hard and there’s something reassuring about having the O/S find the default boot-block without needing human intervention. However the price organizations pay for this convenience is not justifiable. It simply adds waste, complexity, and unnecessary expense to their computing environment.
Traditionally servers have relied on internal disk for initiating their boot-up processes. At start-up, the system BIOS executes a self-test, starts primitive services like the video output and basic I/O operations, then goes to a pre-defined disk block where the MBR (Master Boot Record) is located. For most systems, the Stage 1 Boot Loader resides on the first block of the default disk drive. The BIOS loads this data into system memory, which then continues to load Stage 2 Boot instructions and ultimately start the Operating System.
Due to the importance of the boot process and the common practice of loading the operating system on the same disk, two disks drives with a RAID1 (disk mirroring) configuration is commonly used to ensure high availability.
Ok, so far so good. Then what’s the problem?
The problem is the disks themselves. Unlike virtually every subsystem in the server, these are electro/mechanical devices with the following undesirable issues:
- Power & Cooling – Unlike other solid-state components, these devices take a disproportionately large amount of power to start and operate. A mirrored pair of 300GB, 15K RPM disks will consume around .25 amps of power and need 95.6 BTUs for cooling. Each system with internal disk has its own miniature “space heater” that aggravates efforts to keep sensitive solid state components cool.
- Physical Space – Each 3.5 inch drive is 1” x 4.0” x 5.76” (or 23.04 cubic inches) in size, so a mirrored pair of disks in a server represents an obstacle of 46.08 cubic inches that requires physical space, provisions for mounting, power connections, air flow routing, and vibration dampening to reduce fatigue on itself and other internal components.
- Under-utilized Capacity – As disk drive technology continues to advance, it becomes more economical to manufacture higher capacity disk drives than maintain an inventory of lower capacity disks. Therefore servers today are commonly shipped with 300GB or 450GB boot drives. The problem is that Windows Server 2008 (or similar) only needs < 100GB of space, so 66% of the disk’s capacity is wasted.
- Backup & Recovery – Initially everyone plans to keep only the O/S, patches and updates, log files, and related utilities on the boot disk. However, the local disk is far too convenient and eventually has other files “temporarily” put on it as well. Unfortunately some companies don’t include boot disks in their backup schedule, and risk losing valuable content if both disks are corrupted. (Note: RAID1 protects data from individual disk failures but not corruption.)
Boot-from-SAN does not involve a PXE or tftp boot over the network. It is an HBA BIOS setting that allows SAN disk to be recognized very early in the boot process as a valid boot device, then points the server to that location for the Stage 1 Boot Loader code. It eliminates any need for internal disk devices and moves the process to shared storage on the SAN. It also facilitates the rapid replacement of failed servers (all data and applications remain on the SAN), and is particularly useful for blade systems (where server “real-estate” is at a premium and optimal airflow is crucial).
The most common argument used against Boot-from-SAN is “what if the SAN is not available”. On the surface it sounds like a valid point, but what is the chance of that occurring with well-designed SAN storage? Why would that be any different than if the internal boot disk array failed to start? Even if the system started internally and the O/S loaded, how much work could a server do if it could not connect to the SAN? The consequences of any system failing to come up to an operational state are the same, regardless if it uses a Boot-from-SAN process or boots up from internal disks.
For a handful servers, this may not be a very big deal. However, when you consider the impact on a datacenter running thousands of servers the problem becomes obvious. For every thousand servers, Boot-from-SAN eliminates the expense of two thousand internal disks, 240 amps of current, the need for 655,300 BTUs of cooling, greatly simplifies equipment rack airflow, eliminates 200TB of inaccessible space, and measurably improves storage manageability and data backup protection.
Boot-from-SAN capability is built into most modern HBA BIOS’s and is supported by almost every operating system and storage array on the market. Implementing this valuable tool should measurably improve the efficiency of your data center operation.
I’m frequently surprised by the number of companies who haven’t transitioned to a tiered storage structure. All data is not created equal. While a powerful database may place extreme demand on storage, word processing documents do not.
As we move into a new world of “big data”, more emphasis needs to be focused on making good decisions about what class of disk this data should reside on. Although there are no universally accepted standards for storage tier designations, frequently the breakdown goes as follows:
Tier 0 – Solid state devices
Tier 1 – 15K RPM SAS or FC Disks
Tier 2 – 10K RPM SAS or FC Disks
Tier 3 – 7200 or 5400 RPM SATA (a.k.a. – NL-SAS) Disks
So why is a tiering strategy important for large quantities of storage? Let’s take a look at similar storage models for 1 petabyte of data:
The difference in disk drive expense alone is over $225,000 or around 30% of the equipment purchase price. In addition there other issues to consider.
- Reduces the Initial purchase price by 25% or more
- Improving energy efficiency by 25% – 35% lowers operational cost and cooling requirements
- Substantial savings from reduced data center floorspace requirements
- Increased overall performance for all applications and databases
- Greater scalability and flexibility for matching storage requirements to business growth patterns
- Provides additional resources for performance improvements (an increased number of ports, cache, controller power, etc.)
- A high degree of modularity facilitates better avoidance of technical obsolescence
- May moderate the demand for technical staff necessary to manage continual storage growth
- Requires automated, policy-based data migration software to operate efficiently.
- Should employ enterprise-class frames for Tiers 0/1 and midrange arrays for Tiers 2/3
- Incurs approximately a 15% cost premium for enterprise-class storage to support Tier 0/1 disks
- Implements a more complex storage architecture that requires good planning and design
- Needs at least a rudimentary data classification effort for maximum effectiveness
So does the end justify the effort? That is for each company to decide. If data storage growth is fairly stagnant, then it may be questionable whether the additional effort and expense is worth it. However if you are staggering under a 30% – 50% CAGR storage growth rate like most companies, the cost reduction, increased scalability, and performance improvements achieved may well justify the effort.