Once you have profiled the performance capabilities of your server, begin tuning the system. Tuning an NFS server requires a basic understanding of how networks, disk drives, CPUs, and memory affect performance. To tune the system, determine which parameters need adjusting to improve balance.
Simply adding disks to a system does not improve its NFS performance unless the system is truly disk I/O-bound. The network itself is likely to be the constraint as the file server increases in size, requiring the addition of more network interfaces to keep the system in balance.
Disk drive usage is frequently the tightest constraint in an NFS server. Even a sufficiently large memory configuration may not improve performance if the cache cannot be filled quickly enough from the file systems.
The best way to improve performance for these file systems is to replicate them. One NFS server is limited by disk bandwidth when handling requests for only one file system. Replicating the data increases the size of the aggregate \"pipe\" from NFS clients to the data. However, replication is not a viable strategy for improving performance with writable data, such as a file system of home directories. Use replication with read-only data.
If your environment is data-intensive, stripe the disk with a small interlace to improve disk throughput and distribute the service load. Disk striping improves read and write performance for serial applications. Use 64 Kbytes per number of disks in the stripe as a starting point for interlace size.
Adding a Prestoserve NFS accelerator with NFS version 2 is another way to improve NFS performance. NFS version 2 requires all writes to be written to stable storage before responding to the operation. The Prestoserve NFS accelerator enables high-speed NVRAM instead of slow disks to meet the stable storage requirement.
The NVRAM-NVSIMM Prestoserve NFS accelerator significantly improves the response time of NFS clients with heavily loaded or I/O-bound servers. To improve performance add the NVRAM-NVSIMM Prestoserve NFS accelerator to the following platforms:
For improved performance, NFS server configurations should set the number of NFS threads. Each thread is capable of processing one NFS request. A larger pool of threads enables the server to handle more NFS requests in parallel. The default setting of 16 in Solaris 2.4 through Solaris 7 software environments results in slower NFS response times. Scale the setting with the number of processors and networks and increase the number of NFS server threads by editing the invocation of nfsd in /etc/init.d/nfs.server:/usr/lib/nfs/nfsd -a 64
Data-driven decision making can pervade a school or district and lead to continuous school improvement. Administrators need to ask themselves questions such as, Which decisions do you currently make based on data What decisions do you make that you would like to have more data for, to inform your decision making What do our data tell us we are doing right Where do our data tell us we need improvement Do changes we make result in the improvements we anticipated Are meaningful data on student and management performance regularly collected throughout the year, so that timely, appropriate, and targeted interventions can be applied when and where they are needed
Thinking about our chapter case study of gender diversity in corporate board performance and decision making, men and women can often bring different perspectives to the group, and this diversity may help group performance. In a meta-analysis of gender diversity, Wendy Wood (1987) found that there was some evidence that groups composed of both men and women tended to outperform same-sex groups (either all males or all females) at least in part because they brought different, complementary skills to the group. However, she also found that groups made up only of men performed well on tasks that involved task-oriented activities, whereas groups of women did better on tasks that involved social interaction. Thus, and again supporting the importance of the person-by-situation interaction, the congruency of members and tasks seems more important than either member characteristics or group characteristics alone.
The use of fly ash in portland cement concrete (PCC) has many benefits and improves concrete performance in both the fresh and hardened state. Fly ash use in concrete improves the workability of plastic concrete, and the strength and durability of hardened concrete. Fly ash use is also cost effective. When fly ash is added to concrete, the amount of portland cement may be reduced.
Fly ash is used to lower the cost and to improve the performance of PCC. Typically, 15 percent to 30 percent of the portland cement is replaced with fly ash, with even higher percentages used for mass concrete placements. An equivalent or greater weight of fly ash is substituted for the cement removed. The substitution ratio for fly ash to portland cement is typically 1:1 to 1.5:1.
This fact sheet provides an overview of selected ingredients in dietary supplements designed or claimed to enhance exercise and athletic performance. Manufacturers and sellers promote these products, sometimes referred to as \"ergogenic aids,\" by claiming that they improve strength or endurance, increase exercise efficiency, achieve a performance goal more quickly, and increase tolerance for more intense training. These effects are the main focus of this fact sheet. Some people also use ergogenic aids to prepare the body for exercise, reduce the chance of injury during training, and enhance recovery from exercise [1,2].
Sellers claim that dozens of ingredients in dietary supplements can enhance exercise and athletic performance. Well-trained elite and recreational athletes might use products containing one or more of these ingredients to train harder, improve performance, and achieve a competitive edge. However, the National Athletic Trainers' Association acknowledges in a position statement that because the outcomes of studies of various performance-enhancing substances are often equivocal, using these substances can be controversial and confusing\" .
The preponderance of research to date suggests that exercise-induced reactive oxygen species and nitric oxide are beneficial. These free radicals induce adaptive changes in muscle that lead to greater production of mitochondria and hypertrophy of myofibers [17,21,23,24]. Exposure of cells to high concentrations of various antioxidant supplements (of which vitamins C and/or E have the most evidence) appears to blunt or block cell signaling and thereby inhibit some favorable physiological and physical adaptations to exercise. However, these adaptations might not prevent improvements in VO2max or endurance performance .
Efficacy: A growing number of clinical trials investigating beetroot juice or concentrate as an ergogenic aid have been published since 2007. Beetroot has generally improved performance and endurance to different extents compared with placebo among runners, swimmers, rowers, and cyclists in time trials and time-to-exhaustion tests, but not in all studies [40,41-45]. Performance benefits are more likely in recreationally active non-athletes than elite athletes [42,46]. One study in 10 recreationally active, young male cyclists suggested a dose-response relationship . Although consuming beetroot juice concentrate on each of 4 days to supply 4.2 mmol nitrate (70 ml) provided no performance benefits compared with placebo, larger amounts of juice supplying 8.4 mmol nitrate (140 ml) did. However, consumption of even more beetroot juice supplying 16.8 mmol nitrate (280 ml) produced no further performance benefits. There has been little study of the effects of beetroot on anaerobic performance, such as high-volume resistance exercise with many repetitions .
Implications for use: In a position statement, the Academy of Nutrition and Dietetics (AND), the Dietitians of Canada (DoC), and the American College of Sports Medicine (ACSM) state that nitrate sources, such as beetroot juice, enhance exercise tolerance and economy and they improve endurance exercise performance in recreational athletes . The Australian Institute of Sport supports the use of beetroot juice for improving sports performance in suitable athletic competitions under the direction of an expert in sports medicine, but it notes that more research might be required to understand how the supplement should be used for best results .
Efficacy: Studies have evaluated beta-alanine as a potential ergogenic aid with a variety of participants, exercise and activity protocols, and dosing regimens. Some studies suggest that beta-alanine consumption could provide small performance benefits in competitive events requiring high-intensity effort over a short period, such as rowing, swimming, and team sports (e.g., hockey and football) that involve repeated sprints and intermittent activity . Other studies have found no such benefits . Evidence is conflicting on whether beta-alanine consumption improves performance in endurance activities, such as cycling [53,56]. Experts have not reached consensus on whether beta-alanine consumption primarily benefits trained athletes or recreationally active individuals [53,57]. Studies provide little consistent evidence of a relationship between the dose of beta-alanine and performance effect [51,58].
Implications for use: There is insufficient expert consensus on the value of taking beta-alanine to enhance performance in intense, short-term activities or its safety, particularly when users take it regularly for at least several months. In a position statement, AND, DoC, and ACSM advise that beta-alanine supplementation might improve training capacity and does enhance performance, especially of high-intensity exercise lasting 60-240 seconds, that acid-base disturbances resulting from increased anaerobic glycolysis would otherwise impair . In its position statement, ISSN concludes that beta-alanine supplementation improves exercise performance and attenuates neuromuscular fatigue . The Australian Institute of Sport supports the use of beta- alanine for improving sports performance in suitable athletic competitions under the direction of an expert in sports medicine, but it notes that more research might be required to understand how the supplement should be used for best results . 59ce067264