Different RAID Levels

Written by Ronald Merts

Continued from page 1
RAID Level 3 This RAID level is really an adaptation of RAID Level 0 that sacrifices some capacity, forrepparttar same number of drives, but achieves a high level of data integrity or fault tolerance. It takes advantage of RAID Level 0's data striping methods, except that data is striped across all but one ofrepparttar 107765 drives inrepparttar 107766 array. This drive is used to store parity information that is used to maintain data integrity across all drives inrepparttar 107767 subsystem. The parity drive itself is divided up into stripes, and each parity drive stripe is used to store parity information forrepparttar 107768 corresponding data stripes dispersed throughoutrepparttar 107769 array. This method achieves very high data transfer performance by reading from or writing to all ofrepparttar 107770 drives in parallel or simultaneously but retainsrepparttar 107771 means to reconstruct data if a given drive fails, maintaining data integrity forrepparttar 107772 system. RAID Level 3 is an excellent configuration for moving very large sequential files in a timely manner. The stripes of parity information stored onrepparttar 107773 dedicated drive are calculated using an "Exclusive OR" function, which is a logical function betweenrepparttar 107774 two series that carries most ofrepparttar 107775 same attributes asrepparttar 107776 conventional OR function. The difference occurs whenrepparttar 107777 two bits inrepparttar 107778 function are both non-zero: in Exclusive OR,repparttar 107779 result ofrepparttar 107780 function is zero, wherein with conventional OR it would be one. RAID Level 4 RAID Level 4 is similar in concept to RAID Level 3, but emphasizes performance for different applications, e.g. Database TP versus large sequential files. Another difference betweenrepparttar 107781 two is that RAID Level 4 has a larger stripe depth, usually of two blocks, which allowsrepparttar 107782 RAID management software to operaterepparttar 107783 disks much more independently than RAID Level 3. This essentially replacesrepparttar 107784 high data throughput capability of RAID Level 3 with faster data access in read-intensive applications. A shortcoming of RAID level 4 is rooted in an inherent bottleneck onrepparttar 107785 parity drive. As data gets written torepparttar 107786 array,repparttar 107787 parity encoding scheme tends to be more tedious in write activities than with other RAID topologies. This more or less relegates RAID Level 4 to read-intensive applications with little need for similar write performance. As a consequence, like its Level 3, it doesn't see much common use in commercial applications. RAID Level 5 This isrepparttar 107788 last ofrepparttar 107789 most common RAID levels in use, and is probablyrepparttar 107790 most frequently implemented. RAID Level 5 minimizesrepparttar 107791 write bottlenecks of RAID Level 4 by distributing parity stripes over a series of hard drives. In doing so it provides relief torepparttar 107792 concentration of write activity on a single drive, which in turn enhances overall system performance. The way RAID Level 5 reduces parity write bottlenecks is relatively simple. Instead of allowing any one drive inrepparttar 107793 array to assumerepparttar 107794 risk of a bottleneck, all ofrepparttar 107795 drives inrepparttar 107796 array assume write activity responsibilities. The distribution frees uprepparttar 107797 concentration on a single drive, improving overall subsystem throughput. RAID Level 5's parity encoding scheme isrepparttar 107798 same as Levels 3 and 4; it maintainsrepparttar 107799 system's ability to recover any lost data should a single drive fail. This can happen as long as no parity stripe on an individual drive storesrepparttar 107800 information of a data stripe onrepparttar 107801 same drive. In other words,repparttar 107802 parity information for any data stripe must always be located on a drive other thanrepparttar 107803 one on whichrepparttar 107804 data resides.

CIO/Sr. Vice President for Tornado Computers in Oklahoma City, OK. Located at http://www.tornadocomputers.com

Firewall & Port Basics

Written by Ron Merts

Continued from page 1

The answer is sort of. Picture a computer firewall in terms of its namesake. A firewall in construction terms is a specially insulated wall between office suites or apartments, which prevents fires in one suite from spreading torepparttar next suite. But sometimes builders want water or electrical conduits to pass throughrepparttar 107764 firewall. That's easy enough—they just poke a hole throughrepparttar 107765 wall, run their conduit through, and insulate around it. Computer firewalls let you do just that. They let you open specific ports while keeping other ports sealed off.

Gaming through ICF So when do you need to open ports? Believe it or not, when you want to play client-server games like Return to Castle Wolfenstein or Call of Duty on a distant server, you don't have to open any ports. That's because firewalls block data coming in, but not going out. When your PC sends handshake data out torepparttar 107766 server, a connection is established, and once that connection is fired up, it allows your game to communicate throughrepparttar 107767 firewall.

However, when you wish to host a multiplayer session or play a peer-to-peer game like Age of Empires, you do have to do a little footwork. Inrepparttar 107768 case of starting a server, your PC does not initiate a connection. When you start up a game and choose to host a server, it just sits there and waits for other computers to connect to it. When ICF is in place, those other computers can't connect. In fact, they can't even see that your PC is hosting a server. You'll have to open one or more ports to allow other players to connect to your server. Such is alsorepparttar 107769 case with peer-to-peer games, in which each participant has to connect to everyone else's computer. Thankfully, most games use a client-server implementation.

To open ports in your ICF firewall: 1) Click Start, click My Network Places, and under Network Tasks, click View network connections. 2) Right-clickrepparttar 107770 connection that you use forrepparttar 107771 Internet, and then click Properties. 3) Onrepparttar 107772 Advanced tab, click Settings, and then click Add. Inrepparttar 107773 Description of service box type a name forrepparttar 107774 port you're opening. For example, "Halo Server." 4) Inrepparttar 107775 Name or IP address ofrepparttar 107776 computer hosting this service on your network box, type 5) In bothrepparttar 107777 External Port and Internal Port boxes, typerepparttar 107778 port number you want to open. 6) Click either TCP or UDP, and then click OK. If you're unsure, repeatrepparttar 107779 process for both protocols.

If you choose to make things easier, you can opt to turn off ICF when hosting a game and turn in it back on when you're done. However, this leaves your computer vulnerable while your PC is acting asrepparttar 107780 game server.

Which ports do you open? Different games use different ports and some use TCP, some use UDP, and some use both. You can often find out which ports are used by a given game by consultingrepparttar 107781 game's documentation, its Readme file, or by visiting its Web site and checkingrepparttar 107782 FAQ pages. Some games make port information readily accessible, and for others, it's hard to come by. You might try visiting a game's Usenet group orrepparttar 107783 message boards at its official site or fan sites and posingrepparttar 107784 question: which ports do I open to host a server? In some cases, you'll not only have to open ports forrepparttar 107785 game's own needs, but also to meetrepparttar 107786 needs of its matchmaker service, so that your server can be listed in other players' server browsers.

Be sure to closerepparttar 107787 affected ports when you're not hosting a gaming server to keep your connection secure. That sounds like a lot of footwork, but it's worth it to keep your computer safe.

For more information check out http://www.tornadocomputers.com

CIO/Sr. Vice President of Tornado Computers, Inc. in Oklahoma City, OK.

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