E-Guide DATA CENTER CAPACITY MANAGEMENT

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CAPACITY

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Top items in a capac-ity planning and per-formance monitoring program

Data center cooling and power capacity

challenges egardless of the

size or complexity of

your organization, a capacity planning

and performance monitoring program is

essential for proactive planning and

man-agement of your data center. This e-guide, from SearchDataCenter.

com, lists some important items to include in your data center’s

capacity planning and performance monitoring program. Also,

learn about the most common challenges of data center cooling.

Adequate and efficient cooling is the problem most often cited in

surveys, followed closely by power.

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Data center cooling and power capacity challenges

TOP ITEMS IN A CAPACITY PLANNING AND PERFORMANCE

MONITORING PROGRAM

Regardless of the size or complexity of your organization, a capacity planning and performance monitoring program is essential for proactive planning and management of your data center. Monitoring technical aspects of your environ-ment, such as CPU, disk, memory and network utilization are important, but the ideal capacity planning and performance monitoring program goes beyond these types of measurements and includes both technical operations and busi-ness concerns. This article lists some important items to include in your data center’s capacity planning and performance monitoring program.

1. Set up and follow a regular schedule for review, analysis and presentation of the information you gather. The most important element of any planning and monitoring program is making it a routine event within your organization. Quarterly review and analysis is a good interval to plan for, but it may make more sense for your organization to do this review more or less frequently. Present your findings to stakeholders, along with next steps for addressing

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problem areas.

2. Success and failure rates of backups. Regularly pulling tapes from on- and off-site storage facilities, and restoring files to ensure data is being backed up successfully and is accessible within the timeframe set forth by your organiza-tion, is part of standard operating procedures for many data centers. Analyzing the timing and success/failure rates over time is a good thing to include in your stakeholder presentations. Many stakeholders aren’t interested in the mechan-ics of “how” the process works, but they do want to know that it works and how long it takes to restore a file in the event of a catastrophe.

3. Put together a lifecycle roadmap of standard hardware and software sup-ported in your data center. Get in touch with the product marketing team for the hardware and software you have installed in your organization. Find out the three-to-five year plans for specific features and components of interest to your organization. Keeping up with this information on a regular basis will help you better match up corporate rollout and upgrade plans with the products that will have the longest support window.

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4. Determine which reports your organization really needs. A daily dash-board approach for outages and basic utilization levels is great, and creating trend reports based on the standard information that comes from your moni-toring system is essential. However, your organization may really be most interested in reports that demonstrate cause and effect relationships between seemingly disparate activities, such as the recent implementation of a policy limiting the size of mailboxes and an increase in the amount of space utilized on file servers, as users begin to archive old mail elsewhere in the network.

5. Hardware support and repair. Examine how your current repair process works over time, paying particular attention to speed of resolution and cost of repairs. Your organization may have an extensive hot or cold spare inven-tory, but buying and deploying redundant hardware that the staff isn’t trained on can result in a longer downtime scenario because it takes the staff longer to diagnose and fix the problem. It may be more cost effective to purchase a premium four hour on-site support contract with a vendor to repair/replace/ troubleshoot an issue.

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where critical time is lost during an outage. Track how long each of these repair phases lasts. Use this information to determine where improvements can be made to shorten the duration of the outage. By looking at the tasks performed and how long they take during the initial response -- the troubleshooting and resolution phase, and finally service restoration phases -- an organization can determine if changes need to be made in notification and escalation processes, if additional staff training is required or a platform change for a specific appli-cation would be the most resource and cost-effective way to reduce the impact of outages on your organization.

7. Utilization levels of staff. It’s common to determine how many transac-tions per hour or minute a single server can perform, but typically staffing is reviewed in terms of how many servers can a single administrator support. Complex environments, such as multiple virtual machines on a single server, clusters or multiple servers in a load-balanced configuration to increase the availability of the environment, increase the workload on the administrator. Practical experience shows that organizations with lower administration and engineering skill sets should stick with running multiple servers at lower uti-lization rates. Lack of skilled staff, combined with running clustered servers in

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any OS, can actually reduce availability rather than increase it. It may be more cost-effective to run more hardware in a simple configuration than running less hardware in a more complex configuration with more skilled, and expensive, staff over time.

8. Infrastructure. Don’t forget to review the physical facilities in addition to the computational gear. Electrical and cooling needs should be matched up with the roadmap mentioned in item No. 3 above and planned accordingly. Conversely, if your data center has limited capacity for expansion of power or cooling, selecting server and network equipment with lesser power and cooling requirements is essential. Don’t forget to evaluate infrastructure services like Netegrity, Active Directory, domain name server and Dynamic Host Configura-tion Protocol, as well as racking, cabling and the number of available ports on LAN/WAN/SAN gear with regards to planned upgrades, rollouts or migrations. 9. Staging requirements. The amount of space and resources an organiza-tion devotes to staging equipment for preproducorganiza-tion applicaorganiza-tion testing is an important consideration. Work with development teams to determine the needs for services, such as Active Directory authentication, database space,

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availability and the hours the environment must be available for use. Include these plans and findings in the final analysis of the data center as a whole. It may be possible to identify ways to repurpose staff or equipment from other uses for support of the staging environment on an ongoing basis, limiting the total capital outlay but increasing support services provided for development teams.

DATA CENTER COOLING AND POWER CAPACITY

CHAL-LENGES

The challenges of data center cooling are enormous. Adequate and efficient cooling is the problem most often cited in surveys, followed closely by power. Never the less, many newer data centers don’t cool much more efficiently than legacy facilities. There have been volumes written on both the reasons and the solutions behind cooling problems. This tip offers a reminder of what’s important in the assessment of designs for new facilities, as well as remedies for existing design issues.

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DATA CENTER COOLING: BACK TO BASICS

Although Robert Sullivan (aka Dr. Bob) established the hot- and cold-aisle con-cept many years ago, it still isn’t practiced in all data centers. So I’ll say it once again: Hot and cold air separation is the starting point. Adding more cooling is both wasteful and largely ineffective if you haven’t first employed a contain-ment design.

Equally surprising are all the open rack spaces and unblocked air paths in cabinets and raised floors. Consultants call this “low-hanging fruit,” meaning it’s easy to make a big difference fast by addressing these issues. You can gain a lot, in both data center cooling effectiveness and energy efficiency, and save some expensive consulting fees, by simply closing every unblocked opening. Yet, we find this still hasn’t been done in the vast majority of data centers.

HIGH-DENSITY DATA CENTER COOLING

As important as it is to block unused rack spaces and practice hot- and cold-aisle separation, those tactics still won’t solve everything. The big challenge is high-density heat loads. You just can’t cool cabinets of 15,000 W or more with only conventional under-floor air. Containment will help, but the most effec-tive and efficient way to cool big loads is to get the cooling close to the source of

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the heat. Various forms of in-row coolers, above-cabinet coolers, and rear-door coolers are available. We are probably going to see more direct liquid-cooled servers (either water or refrigerant) in the near future. The key is knowing which data center cooling approach, or combination of approaches, fits your situation, budget and growth expectation. This really should be assessed with experienced, professional help, but consider the following as a quick and simple starting guideline:

In-row coolers provide closely-coupled airflow to the full heights of

cabinets. They also pull most of the hot exhaust air back into the cabinets be-fore it can get over the tops or around the ends of cabinets. But, in-row coolers take up floor space and, despite the supposed flexibility, are rarely moved once they are positioned. They are available in different cooling capacities, in both chilled water and “compressor” versions. Some have humidification options and some do not, so an auxiliary form of humidity control may be necessary. Choosing which type of cooler to use, and properly locating them in cabinet rows, requires knowledge and experience.

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usurp floor space. Different types of cooling units may go in the cold aisle, the hot aisle, or on tops of cabinets, depending on your containment approach. They circulate refrigerant rather than water, which appeals to many people because–when properly configured--refrigerant can be more efficient and safer for equipment than water. However, refrigerant is not as simple to con-nect and disconcon-nect as water, so some units, depending on whether they use water or refrigerant, can be moved around more easily than others. This must be considered if true flexibility is important. Overhead (and some in-row) coolers are also so energy efficient they can be run on uninterruptable power supplies (UPSes) to achieve “cooling ride-through,” with the UPS continuing to run the cooler through short power disruptions. This capability can be critical with very high-density servers. Some refrigerant-type coolers have minimum heat load requirements for operation, so they need to be chosen carefully. Most in-row or overhead coolers may remove too much humidity from the air, so another means of humidity management is necessary. That is usually accom-plished with conventional perimeter air conditioners that also provide base cooling.

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rear-door coolers (no fans) have been shown in independent tests to be even more energy-efficient than in-row or overhead devices. Most passive rear-door coolers use chilled water and therefore require an extensive piping network under the floor or overhead. They can be added to standard cabinets, but using them in a data center that also has cabinets without rear-door coolers raises a challenge. The purpose of rear-door coolers is to exhaust cool air. But conven-tional air conditioners work best with higher return air temperatures, so this creates an anomalous situation. Rear-door coolers have no humidity control, and are generally set to maintain four degrees Fahrenheit above dew point to avoid condensation. Therefore, they require conventional air conditioners for humidity control and to cool racks and cabinets that don’t justify rear-door coolers. A design incorporating rear-door coolers is the antithesis of normal best practice today, in that recirculation over cabinet tops and around row ends is necessary. If the entire room is cooled with rear-door coolers, it is even possible to use legacy front-to-back cabinet arrangements instead of hot- and cold-aisle designs.

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POWER IS THE CULPRIT

All this heat comes from power, and for some, that’s as big a problem as data center cooling. A shortage of kilowatts mandates a thoughtful balancing act; if you use too much power to run the computing equipment, you won’t have enough left to cool it. So the first step is to reduce equipment power consump-tion, which will also reduce the cooling power required. Turn off unused or underused servers (and see if anyone yells) and enable energy-saving features. You may even have unnecessary air conditioners. In one case, a new installation was out of space and power, had air conditioners all around the room, but still had hot spots. For this scenario, cutting back to two computer room air condi-tioners actually improved cooling. Removing all but four left 2N redundancy, reclaimed space and yielded extra power. Problem solved!

ADD UPS CAPACITY THE RIGHT WAY

If you have plenty of utility power but too little UPS capacity, there are good and bad ways to fix that too. The bad way is to put in another big UPS, either in addition to the existing UPS or as a replacement for it. Another bad approach is to add small UPS units to cabinets all over the room. This is a reliability and battery maintenance nightmare. Today, we have ways of adding UPS capacity

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incrementally. Some systems are modular, with smaller plug-ins that admin-istrators can add as the need for capacity grows. Others enable the additional capacity via firmware. Either way, the goal is two-fold: to pay only for the capac-ity you need, when you need it, and to “right size” the UPS to maximize energy efficiency. Another advantage of incremental solutions is the ability to have an N+1 configuration for a little more money than an N design, providing a level of redundancy you may not have been able to previously cost-justify or find space for.

VERIFY ACTUAL UPS USAGE

Before upgrading a UPS, administrators should first determine if they are re-ally out of capacity. Check the loads for phase balance. Unless all three power phases are reading close to the same power draws, there is still unused UPS capacity, even if the UPS says it is at 98%. An administrator would need to re-plug loads, and potentially add some branch circuits,but it will still be easier and cheaper than purchasing a new UPS. Putting “smart” power strips in cabi-nets could help as well. These sophisticated power strips (unfortunately called power distribution units [PDUs] by many people, which confuses them with the large, true PDUs we have known for decades) have local power draw displays,

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as well as remote power readouts via the network. This makes it much easier to find and correct phase imbalances.

In short, don’t just add UPS or air conditioning capacity without knowing what’s really needed. And be suspicious of legacy solutions proposed for mod-ern problems. You shouldn’t open a paint can with a steak knife. There’s a tool for every job, as well as a right and wrong way to use it.

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