【 Weak current College 】 purchases four misunderstandings of the digital camera

The camera can be regarded as the last few years just pop up a digital product, QQ chat, video conference, is it a thirst. Even miles between friends, as long as we have it and the Internet, we can speak of "face to face", very convenient. With the growing popularity of broadband by now, the camera is also rapidly developing, family, Internet cafes, offices, can see it, to introduce consumers to buy a camera that is easy to fall into four major mistakes.
Myth 1: pixels higher the better?
　　
"This is how many megapixels?", this is a lot of friends to buy a camera is asked most frequently in a Word, but businesses often brag about it in this regard, the big blow products how to how good, how the pixels high, how how to clear the screen. So, what exactly has played pixels of a pixel? is higher, the more clear image?, we know in fact not the case, the image sensor has a number of photographic elements, each of the photographic unit corresponds to one pixel, the more pixels, the image is generated. And as for the image if it is clear, light look pixel but no, it's also the lens material, software, processing, and other aspects are closely linked.

In addition, in the market we have common camera pixels are generally 30 million or 35 megapixels, and some businesses tend to say that their products can reach the interpolation 120 megapixels, which is all about?, the camera is using the software interpolation work out, simply put is 640 x 480 pictures widen to 1024X768, then use the software calculates the picture resolution of differences between the points, the middle color of the part of the fill color of calculation software. Do while output pictures, but the quality of the image and no real improvement, or even possibly serious distortion.

Therefore, we purchased the camera must be kept in mind: pixels and the image sharpness is not absolute.
　　
Myth 2: CCD than CMOS?

In fact, the structure of the camera is not complicated, itmainly by the DSP (master IC), SENSOR (photographic equipment), LENS (lens) and peripheral circuits and software driver combinations. With photographic devices is a major technical core, its principle basically consistent with DC, DV. In today's digital imaging fields, photosensitive cells simply CCD or CMOS, including former development time longer, in DC or DV areas more widely applied; and our common camera you use relatively inexpensive CMOS-sensor. But you can never think that a certain ratio using CCD CMOS camera, it's only manufacturer of selling points too! small series have used a large domestic 1XXX element of the camera, the sensor is CCD, however the actual use of results and compare "COMS camera" is not an absolute advantage, even in clarity also slightly less.

Therefore, we buy the camera, don't blindly believe businesses, use COMS's camera isn't the difference than CCD, we need to spend more than 10 times the money on?

Myth three: lens really matter?
　　
A lot of friends when buying a camera, just think of cheap or light thinking pixels, completely ignored the lens is good or bad. The camera's lens is made of glass or plastic lenses. Glass lenses are not only more expensive than the cost of plastic lenses, light transmittance and imaging quality also has a large advantage. However, many small plants, in order to save costs, and the pursuit of high profits, often reduce the number of lenses, or use the cheap plastic lens. Although these products are much cheaper in price, looks very attractive, but the actual image is but it is unable to compliment.
　　
So we buy the camera, not just for the sake of cheap, or try to choose glass LENS of the camera as well.

Myth 4: Mike function really practical?
　　
Individual merchants in marketing their business camera, touted the camera's Mike function. UH! camera + mic sounds all well and good, but if you buy a home with you, you will find, in fact, did you imagine so chic: video chat, in order to enable each other to hear your voice, you need to reach the camera neck, to no, you have to simply hold the camera when the phone is used, of course, at that time can see you and that is another matter.

Of course, the we do not rule out some excellent quality MIC effect, good camera does occur, but if this camera and ordinary post is too large compared to it, we really need to buy? as single a MIC, the effect is excellent, price/performance ratio and high, why?

Therefore, we buy the camera, never too much about those "chicken" function, there is no good, of course, it does not matter, there is no need to waste money in these areas.

【 Weak current College 】 a computer host with two monitors and two sets of keyboard for twin share a host---Power By 【 China power house network 】

In general you want to set up a local area network, the two hosts were indispensable, but even the simplest-to-peer networks also need two network cards and twisted-pair, better now, and as long as the host has two display interface, connect both monitors and two sets of keyboard, and then use BeTwin software (http://download.enet.com.cn/html/060562002032501.html) can let two people simultaneously with this host. From the equipment cost, the advantages of this option is quite obvious. BeTwin supports up to 4 users, relative to the LAN hubs, routers, and other inputs, saving a lot of costs.


Easy hardware connections
Since most users of the computer can only receive one monitor, so it is first necessary to resolve the problem, dual-display-shows the programme there is a lot like AGP video card and PCI video cards programme, onboard video and PCI video cards, PCI video card + PCI video card programmes and a dual-head video card programme.
To-head video card, for example, if the video card has two D-Sub interface, you can directly use dual VGA output to display, if the video card is a D-Sub interface and a DVI connector, connect the two D-Sub interface, you will need to purchase a monitor DVI go D-Sub adaptor, and then put both monitors respectively, two video cards. First of all, the primary monitor is connected to the first D-Sub interface, then the secondary monitor is connected to the second D-Sub interface, if the second interface to DVI interface, DVI go D-Sub go connector to the DVI connector on the video card, and then the secondary monitor is connected to the Ext connector (Figure 1).

Figure 1

Then connect the peripherals, in General, each user needs to configure a set of mouse, keyboard, this is the most basic needs. Users can use PS/2 interface with USB-keyboard, USB keyboard, or use the double. In addition, you need to host has two audio, dual sound card application is relatively simple, as we can on the basis of the integrated sound card, you can install a PCI sound card. In addition, various USB game handle can also be very good support, everything after installation is complete, the system will detect multiple monitor, mouse and keyboard. Note that if a monitor, keyboard, mouse, any one of them is not connected properly, can result in WindowsXP BeTwin configuration system error.


Simple device settings by default, only the primary monitor will display that to achieve the dual display, you need to enter the "display properties" in the "settings" tab, you can see two display devices, select the second monitor, and then click the "extend my Windows desktop onto this monitor", confirmed the second monitor will show the desktop, and the mouse cursor can be moved between the two monitors.
Figure 2

Run BeTwin software, click the "workstation configuration" menu, "workstation configuration" button, then select "add new workstation", enter the name of the workstation and determine, BeTwin will search system in all of the monitor, keyboard, mouse, game handle peripherals, and display all of the hosts and clients that hosts a default name is "HOST" (Figure 3).

Figure 3

Click the "hardware configuration" button, will all be reassigned hardware using the left button, move it to the "free hardware", the main distribution of the sound card, video card, video card, as well as mouse and keyboard, the allocation method is simple, to the sound card, for example, for example, to assign the PCI sound card "1" BeTwin workstation, as long as the selected PCI sound card device, and then use the right arrow button, the audio will be assigned to the "BeTwin workstation 1", in addition to the integrated sound is assigned to the "HOST," host using the same method to assign the video card, mouse, keyboard and other device.

Because BeTwin also supports four users, we may choose in the main interface BeTwin "add workstation" adding more users, but to ensure system stability and speed of work, it is recommended that two users sharing a single host, and the computer for more than two displays, light and a sound card is too much trouble, the successful implementation of a two-person BeTwin, and use two separate computers, do not interfere with each other, give full play to the PC must have the potential. Another powerful feature comparison BeTwin, users can press their need for reasonable setting.

【 Weak current College 】 how to get rid of email viruses five tips

The first type, choose a reliable antivirus software

To deal with e-mail virus, in the message received the virus scanning filter harmful virus is a very effective means. The user can keep the anti-virus monitor feature in mail, setting the message monitoring feature, you can receive messages for viruses, effectively prevent e-mail virus invasion. Shenzhen Server lease

The second type, periodic upgrade virus library

In particular, the antivirus software vendor to upgrade service is very attentive to its software virus definitions are in constant update status, manufacturers will be according to a recent popular virus, the virus code at any time to update to virus library, if the user does not timely upgrades, it's hard to take on new virus killing, then you can't blame the antivirus software can't find viruses.

The third type, identifying e-mail virus

Some e-mail virus has a wide range of common characteristics that identify their common ground can prevent the destruction of a sector viruses. When you receive the message, look at the size of messages, if you find messages in the content, no attachments, the size of the message itself and dozens of K or greater, then the message may contain a virus, you can register directly from the computer, and then empty the waste Inbox; remember, the next step is very important, in the after emptying the waste Inbox, be sure to compress it again mailboxes, or antivirus software in the next virus checking also reported a virus; if you find a message you receive each other's address is unknown, the domain name on a very not like normal internal mailbox, it will most likely receive a virus, this time, you can also choose to delete directly. See attachment extension name, if it is a double suffixes so most likely is a virus, because e-mail virus will choose to hide in the attachment, you can directly book subject. Shenzhen Server lease

The fourth type, let mail monitoring function

Many users to purchase anti-virus software, because of some reason not open real-time monitoring of the firewall, because anti-virus software is running in some consuming system resources, but this is inevitable, it depends on how the regulation of the use of the user. If you do not open the real-time monitoring capabilities that will allow email viruses and other computer virus took advantage of the drill, not of the empty child protection measures in the presence of computer viruses with almost no ability to resist. Therefore, in order to secure protection of computers, a virus monitoring capabilities to run.

The fifth type, test

When faced with an attachment of the message, if the attachment is executable (*.exe, * .com) or a macro function in Word document, do not select open, you can use two methods to detect viruses. One way is to use antivirus software e-mail virus monitor feature to filter out virus in mail. Alternatively, the annex to the other exists on your hard disk, and then use anti-virus software to carry out virus checking.

【 Weak current College 】 data archive disk storage selection

Most enterprise database data flow in growth, but the lack of control, even cannot control, money, power and data center space are limited resources, the database on the utilization of these resources must be increased.

Supplier of many ways to improve the efficiency of data archiving solutions. Data reduction techniques such as compression, single instance storage (singleinstancestorage) and most powerful sub-file de-duplication technology, this enables suppliers to 30lbs data loading 10lb data archiving. When you are not using Spinningdisk, shut it down, regardless of vendor called MAID (Copan, Nexsan) or HDS, its the 1TB drive energy consumption from 7.5W reduced to less than 1W.

But even if these drives are stopped, the MAID system still consumes is greater than or equal to its normal run-time 30% more power, because in the low-load, low-power supply efficiency. The processor is in idle state still has the power consumption, but idling memory and an up-to-date level of idling server processor EnergyStar (consumption electricity to 55W), or not.

Data archiving storage of the simplest system, I call it locked NAS (lockedNAS). Vendors including NetApp and Sun company has expanded its file system and NAS operating system will remain in the implementation of the guarantor force add in. They are modelled on the NetApp SnapLock naming patterns, the latest improvement technology of date to the end of life equipment, playing on the "read-only" flag. Such a system would be in the life of the end-to-read-only portion of the reset.

LockedNAS general system, but lack the last time I mentioned a few other features.

While NetApp file compile stalls Member verification each have many cluttered information integrity of the data block, it does not operate in the background, in case any problems are found or remotely obtain a corrupt local data block of the full version. Scalability and long-term extension is a problem, because increasingthe drive as well as every 5-7 years data transfer (because your enterprise vendors maybe will no longer support your business system) and is not a good way to solve the problem.

Disk-based data storage archiving this market sector, another competitor is ContentAddressableStorage, using each storage destination (file, email information, etc.) of the hash as a storage target (instead of the file position) of important identifier — with NAS system. And usually thinking different, CAS systems do not use the full-text index as its location, but only a hash of the selected storage object. In fact, most CAS systems, including EMC Centera, Nexsan Corporation Assurion and Caringo CAStor, the company did not give its storage content indexing.

Their internal implementation of single instance storage (for example copy the same file multiple times will cause the same redundant data), or check the filehash, to consolidate data in the background. In addition to most of the file system supports name, owner, and time stamp, most CAS system can store extended metadata. As a result, the most complex application programming interface is used for file storage and recovery, data archiving software vendors to write and test the interface. SNIA standard XMLAPI--known as XAM, a year after the first appear in the CAS, and other fixed-content storage system.

CAS suppliers attach great importance to extend metadata. ILM (currently just a concept, not products) for data classification features, functionality, and similar e-discovery capabilities are required in addition to the name and date of other data to make decisions. I have doubts that need to store a special file system API. Data archiving software or a content management system is only able to add metadata and all important full text index into independent of the file system of the database.

Some vendors have built similar NAS device, using the hash to ensure that the integrity and identify the unique identity of the data, not as the main address of the target data. Like DataDomain company equipment and NEC's Hydrastor, have all been as a backup target, but its features, and data archiving device level. DataDomain unit for data preservation and removal, and the functionality the same. Permabit company EnterpriseArchive adopt similar hash to assist in the management of NAS data.

Many such systems with RAIN (redundant array of independent nodes) structure, so a 2U server into a 1u and built-in storage groups or the distribution grid support and management of data in the array. Some systems use absorption/fix nodes, these nodes can manage the hash data to and receive data while storage support data nodes. Some systems also have both features.

If you were able to complete implementation, RAIN patterns will make 100 nodes for scalability, new nodes are available to scalability, processor speed, disk capacity, and will increase a array, once placed in the old slow node or there is a problem with the data on the nodes will be resettled, then the old node will be replaced by a small number of hits or command. However, most of the RAIN system has an associated high speed processor, this can lead to an increase in power consumption, while at the same time might cause access times fewer large data archiving to consume too much.

【 Weak current college 】 technical basis on standby

Hot standby in long-term use has a lot of users have summarized many of the skills experience, there are some concepts are more we need to know about, the following is the details of hot standby technology need to understand the concept.

Hot standby technology needs to be pointed out a few concepts:

1. standby technology works

Fault isolation, simple, high-availability (hot) is a kind of the point of failure to protect the transfer of business continuity. Its business recovery is not in the original server, which is in the standby server. Hot does not have the repair the failed server's features, but only fault isolation.

2. standby mode technical Active-Active

Active-Active way refers to the business rather than the server status, if the same application is not complete Active-Active manner. For example, hot two servers is sqlserver database, it is referring to a different database instance. The same database instance is not possible in hot this level Active-Active manner. Simple Active-Active is two way run to Active-Standby on both servers.

3. Standby failure detection

Fault detection is hot standby technology tasks, different double machine detection point number determines the hot standby software in functionality and performance of good and bad, not all software will have the same detection capabilities to PlusWell camputer technology software, for example, it provides a full system detection capability, that is, there are system-level detection, application-level, network level three. System-level testing through hot standby technology software provides a system for the detection of cardiac function, the application level provides the user applications, databases, and other detection feature, the network level detection provides network connection detection and optional on network path detection capabilities, so called full fault detection capabilities.

4, server resources

Hot standby resource refers to a business operation relies on the smallest of the associated services, different two-machine software provides resources, how many different, of course, you can toggle the resources available, the more software applications, also in hot standby technology in server resources mainly include, switch network IP resource, computer name, disk volume resource, the server process.

5, hot standby switch technology

-Standby switch generally consists of manually switch and failover, which is planned to switch (i.e. people switch) and non-planned switch (failover).

Need we note that not all resources have to switch to PlusWell hot backup software as an example he provides:

(1) local resource monitoring, that is not switching resources.

(2) ordinary resource, that is, you can switch the main machine resources.

(3) quick resources refers to quickly switch resources

In the General case of dual switching time is 1-5 minutes, and quickly switch in time is 3-5 seconds. Users should be according to their needs and operational features to select relevant switching service, from the price-cost point of view, the switching time that costs are also higher.

6. standby technology copy and backup concept is the difference between

Hot Backup refers to: highavailable is highly available, while the backup is a Backup, data backup, this is two different concepts, products are two functions on an entirely different product. Hot backup main guarantees the continuity of the business, realization of methods is the point of failure and backup of the transfer, the primary objective is to prevent data loss, do a test Bay, so backup is data recovery instead of application failover.

【 Weak current College 】 standby service reorganized necessity

Hot standby service is a lot of enterprise is in use or is starting to grow old with technology. As the technology development we have a certain experience. Long time of use, which is enhanced by our understanding of the technology. Hot standby service concept includes two broad and narrow.

Broadly speaking, it is important, use two servers, each backup to perform the same service. When a server fails, you can from another server, bears the service task, which does not require human intervention, automatically ensure that the system can continue to provide services.

Hot standby generally require shared storage devices. But in some cases you can also use two separate server.

Implement hot standby service needs through professional cluster software or computer software.

In a narrow sense, hot standby service especially based on active/standby mode Server hot. Server data includes database data simultaneously to two or more servers, or use a shared storage device. At the same time, only one server running. When running a server fails to start, another backup server software consultation survey (typically by heartbeat Diagnostics) to activate the standby machine, ensure that application in a short time to completely back to normal use.

Why do hot standby? hot standby service is the server's fault.

Server failure could be caused by a variety of reasons, such as equipment failure or operating system failure, software, system failures, and so on. Generally speaking, the technical personnel at the scene, the recovery server normally might need 10 minutes, hours or even days. From practical experience, unless you simply restart server (with possible risks still exist), or they often take several hours. But if the technician is not in the scene, the recovery service time is longer.

But for some important system, the user is very difficult to put up with such a long interruption in services. Therefore, you need to pass the hot standby service, to avoid prolonged interruption in services, ensure the system is long-term, reliable service.

Decide whether to use standby service, the correct approach is to examine the importance of the system and the degree of service interruption, to determine whether to use a hot standby. That is, your users can tolerate long recovery service, if the service cannot be restored will cause many influences.

In considering the hot standby service, you need to note that general sense of the hot standby will have a switch, the switch process may be a minute or so. During the switching, service is possible short outage. However, when the switch is completed, the service will resume normal. Therefore, the hot standby service is seamless, uninterrupted, but it can guarantee that in the event of a system failure, the ability to quickly restore normal service, the business will not be affected. But if you do not have a hot standby, in the event of a server failure, there may be several hours of service interruption, the business impact can be very serious.

Another point that needs to be stressed that the server failure and switches, storage devices, the concept is much higher. Because the server is compared to the switch, storage devices, much more complex equipment, but also includes hardware, including operating system, application software system of complex systems. Not only the equipment failure could cause service disruption, and software issues may also cause server not working properly.

It should also be noted that some other protective measures such as a disk array (RAID), data backup is very important, but it cannot replace the role of standby service.

【 Weak current College 】 hot backup mode in fault-tolerant server application---Power By 【 China power house network 】

Hot backup method of determining is a business to own data protection of important links, a good way to data recovery rate and enterprise business sustainability. The hot-standby mode using two configuration identical server system, in fact, server cluster scenario of fault-tolerant technology is also a multi server fault-tolerant technologies.

While this section is to describe a single fault-tolerant technology is a server for high performance, fault-tolerant, its tolerance to far more than the server cluster and hot-standby mode fault tolerance to high, and therefore more suitable for those such as securities, telecommunications, financial, medical, etc. on fault tolerance special demanding industry.

Previous cluster system in the event of a failure, you need to interrupt the operation of the server, and then use the time to switch to the standby server to run above in order to carry out the repair and recovery, including the cost and loss is the user's wish to see. A fault-tolerant technology for fault-tolerant servers, the biggest advantage is that it can automatically isolate fault module, without disrupting the running module replacement for damaged parts for maintenance, and all physical fault elimination, the system automatically resynchronize run, thereby effectively solves the customer's extra worries. It is precisely for this reason, a fault-tolerant technology for fault tolerant server, is the impact of the rise of the previous years standby mode and cluster technology, more and more people are concerned about. Also, more importantly it can use industry-standard components of the server implementation (IA), competitive cost advantage that makes impressive fault tolerant servers.

Fault-tolerant server is through the CPU clock frequency, the system all hardware backup, including CPU, memory, and i/o bus, redundant backup; through system all redundant parts of synchronization run, realize the true meaning of fault tolerance. Any part of a system failure will not result in system failure and data loss. There are many fault tolerant system is based on IA Server, fully compatible with Windows2000, previously only on RISC systems, fault-tolerant can be achieved. This fault-tolerant technology in IA Server implementation, IA server reliability to 99.999 per cent, while the server is running is uninterrupted.

Standby mode and fault-tolerant servers positioned slightly different, this is determined by the difference between realization of availability. Hot backup mode in General can implement 99.9% availability, fault-tolerant servers can achieve 99.999% availability. In this way, most of the hot-standby mode applications in business continuity is not very strict industry, such as public security system, forces system or individual manufacturers, these industry allows data to be interrupted for a short period of time. While such as telecommunications, banking, securities and health care, and other demanding industries is a fault-tolerant servers all over the world. Also note that hot backup and server cluster does not like the hot backup usually require two way server configuration, and the server cluster is not strictly required, it is confusing to many readers.

In addition, because of the hot-standby mode requires at least 2 servers, resulting in the purchase of software (operating systems, middleware, dual backup software, etc), software maintenance, upgrades, system hardware upgrade needs more than a single fault-tolerant way 1 x additional inputs, and two-computer backup software failure, the maintenance of a high degree of difficulty, the customer will bring greater difficulties. Therefore, although the single fault-tolerant server hardware costs more than double machine backup mode of hardware input, while its total cost of ownership (TCO) is far below the double machine backup costs. But its flexible configuration, the hot backup mode more advantages, many hot backup scenarios are some systems integrators combine different manufacturers server products to meet different customer needs. But overall, fault-tolerant server is the future trend of development.