Different RAID Levels

Written by Ronald Merts

Different Types of RAID RAID Level 0 RAID Level 0 or striping is optimized for performance atrepparttar expense of fault tolerance. Drives in a RAID 0 array organizes data in such a way that it is striped acrossrepparttar 107765 multiple drives. A RAID Level 0 array can contain any number of stripes. In RAID 0 if you have 2 x 60 gig drivesrepparttar 107766 array size will be 120 gig. The reason RAID 0 is a performance-enhancing configuration is that striping enablesrepparttar 107767 array to access data from multiple drives atrepparttar 107768 same time. In other words, sincerepparttar 107769 data is spread out across a number of drives inrepparttar 107770 array, it can be accessed faster because it's not bottled up on a single drive. This is especially beneficial for retrieving very large files, since they can be spread out effectively across multiple drives and accessed as if it wererepparttar 107771 size of any ofrepparttar 107772 fragments it is organized into onrepparttar 107773 data stripes. The downside to RAID Level 0 configurations is that it sacrifices fault tolerance, raisingrepparttar 107774 risk of data loss because no room is made available to store redundant data. If one ofrepparttar 107775 drives inrepparttar 107776 RAID 0 fails for any reason, there is no way of retrievingrepparttar 107777 lost data as can be done in other RAID implementations described below. RAID Level 1 The RAID Level 1 is achieved through disk mirroring, and is done to ensure data reliability. RAID 1 also enhances read performance, butrepparttar 107778 improved performance and fault tolerance are atrepparttar 107779 expense of available capacity inrepparttar 107780 drives used. In RAID 1 If you have 2 x 60 gig drivesrepparttar 107781 array size will be 60 gig. In a RAID Level 1 configuration,repparttar 107782 RAID management software instructsrepparttar 107783 subsystem's controller to store data redundantly across a number ofrepparttar 107784 drives (mirrored set) inrepparttar 107785 array. In other words,repparttar 107786 same data is copied and stored on different disks known as mirroring to ensure that, should a drive fail,repparttar 107787 data is available somewhere else withinrepparttar 107788 array. In fact, all but one ofrepparttar 107789 drives in a mirrored set could fail andrepparttar 107790 data stored torepparttar 107791 RAID 1 subsystem would remain intact. A RAID Level 1 configuration can consist of multiple mirrored sets, whereby each mirrored set can be a different capacity. Usuallyrepparttar 107792 drives making up a mirrored set are ofrepparttar 107793 same capacity. If drives within a mirrored set are of different capacities,repparttar 107794 capacity of a mirrored set withinrepparttar 107795 RAID 1 subsystem is limited torepparttar 107796 capacity ofrepparttar 107797 smallest-capacity drive inrepparttar 107798 set. The read performance gain can be realized ifrepparttar 107799 redundant data is distributed evenly on all ofrepparttar 107800 drives of a mirrored set withinrepparttar 107801 subsystem. The number of read requests and total wait state times both drop significantly; inversely proportional torepparttar 107802 number of hard drives inrepparttar 107803 RAID. RAID Level 2 RAID Level 2 is rarely used in commercial applications, but is another means of ensuring data is protected inrepparttar 107804 event drives inrepparttar 107805 subsystem incur problems or otherwise fail. This level builds fault tolerance around Hamming error correction code (ECC), which is used as a means of maintaining data integrity. ECC tabulatesrepparttar 107806 numerical values of data stored on specific blocks inrepparttar 107807 virtual drive using a special formula that yields what is known as a checksum. The check-sum is then appended torepparttar 107808 end ofrepparttar 107809 data block for verification of data integrity when needed. As data gets read back fromrepparttar 107810 drive, ECC tabulations are again computed, and specific data block checksums are read and compared againstrepparttar 107811 most recent tabulations. Ifrepparttar 107812 numbers match,repparttar 107813 data is intact; if there is a discrepancy,repparttar 107814 lost data can be recalculated usingrepparttar 107815 first or earlier checksum as a reference point.

Firewall & Port Basics

Written by Ron Merts

Gaming in general is fun, but there's something about multiplayer gaming that's even more enjoyable. Perhaps it'srepparttar satisfaction of realizing thatrepparttar 107764 car you just passed inrepparttar 107765 last lap is being driven by a real person, like you, and not some computer program.

Butrepparttar 107766 Internet connection that makes gaming so much fun also serves as a doorway through which nefarious hackers can send malicious code, causing havoc with your computer. Broadband users are especially fertile targets for bad seeds. That's why a firewall is so important. A good firewall, such as Internet Connection Firewall (ICF) that comes with Windows XP, protects your computer from attacks.

A firewall works by blocking communication ports that are used to transfer data to and from your PC. However, games (and all applications that work over repparttar 107767 Internet) use those ports to communicate. This raises some questions that we frequently encounter on message boards and inrepparttar 107768 Usenet: how does a firewall affectrepparttar 107769 performance of online gaming? What do you have to do to enjoy online gaming with a firewall in place? I'll answer these questions in this article.

How Ports Work To getrepparttar 107770 most out of online gaming through a secure connection, you have to have some idea of how games communicate overrepparttar 107771 Internet and how a firewall works. Don't worry; this discussion won't get inaccessibly technical. I'll stick to layman's terms. To start with, let's look at how programs talk to each other overrepparttar 107772 Internet. All Internet-aware programs communicate with each other through ports. What, exactly, is a port?

Think of your Internet connection as a water conduit. But instead of thinking of it as one big pipe, picture it as a conglomeration of thousands of small pipes: 65,535 of them, to be exact. That isrepparttar 107773 number of Internet ports through which communications can take place.

Different services use different ports—the assignment of which service uses which port is more or less arbitrary. For example, World Wide Web communi- cations use port 80. Why port 80? Because a few years ago, a bunch of Internet-related people got together and decided that that's how it would be. Similarly, SMTP e-mail traffic uses port 25. Those same people decided that that's how that would go, and so on. These and other services use protocols to transmit and receive their data through these ports. Two protocols that they use are Transmission Control Protocol (TCP) and User Datagram Protocol (UDP).

The 65,535 ports are divided into three groups: Well Known Ports (ports 0 through 1023), Registered Ports (ports 1024 through 49151), and Dynamic or Private Ports (allrepparttar 107774 rest). A list of port numbers and what services commonly use them is kept up byrepparttar 107775 Internet Assigned Numbers Authority.

Like other services,repparttar 107776 Internet components of games use ports and protocols to communicate overrepparttar 107777 Internet. When you play Halo online with a bunch of other people, it has to transmit your keyboard and mouse-click data torepparttar 107778 server so it can tell when you move around or fire your weapon. In turn it has to transmit world data back to your computer so you can see where other people move so you can aim at them and chase them around. Halo and other multiplayer games likerepparttar 107779 Quake family, Half-Life and mods such as Team Fortress Classic andrepparttar 107780 popular Counter-Strike, Medal of Honor: Allied Assault, Battlefield 1942 send their data down ports and listen for data fromrepparttar 107781 same or other ports. Game matchmaker services like GameSpy Arcade also use ports to communicate.

Firewalls block ports. They are, by their very nature, communications- blocking applications. By closing off ports, they prevent malicious entities from gaining access to your computer through your Internet connection. But doesn't that mean they also block traffic for benign applications that you want to have access torepparttar 107782 Internet, such as your Web browser, your e-mail application, and online games?

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