# 5 COMPUTER STORAGE

SOLID STATE DRIVES

Solid state storage devices store computer data on non-volatile "flash" memory chips rather than by changing the surface properties of a magnetic or optical spinning disk. With no moving parts solid state drives (SSDs) -- are also very much the future for almost all forms of computer storage.

Sometime in the second half of this decade, solid state drives are likely to replace spinning hard disks in most computers, with several manufacturers now offering hard-disk-replacement SSDs. These are often very fast indeed, extremely robust and use very little power. As pictured above, typically today most hard disk replacement SSDs are the same size -- and hence a direct replacement for -- a 2.5" hard drive. They also usually connect via a SATA interface.

Unfortunately the prices of solid state drives are currently high, with the lowest capacity disks . At present SSDs are therefore generally only being used in high-end PCs and laptops, and as a means of increasing robustness, reducing noise, decreasing power consumption, and often significantly decreasing boot-up times.

As a notable exception, for a couple of years some ultramobile "netbook" computers and some low-power desktop computers -- such as the Asus Eee PC -- used an SSD rather than a traditional hard drive, and which was made cost-effective by limiting disk sizes to around 4-8GB. Sadly, on netbooks this trend has now died out. However, the new Google Chromebooks are SSD-based.

# 4 COMPUTER STORAGE

EXTERNAL HARD DISKS / DIRECT ATTACHED STORAGE (DAS)

A hard drive is a computer component that holds data. Every computer needs at least one hard drive to store its operating system, programs and user information. This drive usually is internal, or built into the computer, but as computer systems have evolved and different needs, threats and circumstances have arisen, external hard drives have become more popular. External hard drives usually are used in addition to internal hard drives in order to store more data. They also allow the user to put sensitive, confidential or otherwise important information on them, then disconnect them and store them in secure locations.

Physical Characteristics

An external hard drive sits outside the main computer tower in its own enclosure. This portable encasement is slightly larger than the hard drive itself, and it sometimes contains a cooling fan. The external hard drive is connected to the computer via an interface cable, which allows the external hard drive to communicate with the computer so that data can be passed back and forth.

Why It is Needed

Internet access regularly exposes computers to potential security threats such as Trojan horses, viruses and spyware. It has become increasingly difficult to guard against these threats, even when employing firewalls and antivirus programs. Aside from online threats, multiple family members often use the same system, putting sensitive documents at higher risk of inadvertent corruption or loss. Additionally, the space required for multimedia storage has soared, with digital media files often taking up large amounts of space on a user's hard drive. All of these concerns can be addressed with an external hard drive.

Advantages

A portable or external hard drive allows the user to back up or store important information separate from the main internal hard drive, which could become compromised, damaged or corrupted. Sensitive documents, large music files, movies, images and other backup files can be kept securely and safely on an external hard drive. Another advantage of an external hard drive is that it is portable and operates on a plug-and-play basis so that other compatible computers can recognize the drive as a storage device and can be used to access the files. A user can easily transfer files from the computer to the portable hard drive or from the portable drive to the computer, or programs can be run directly from the portable hard drive.

source : wisegeek

#3 Computer Storage

RAID

On servers and high-end PC workstations (such as those used for high-end video editing), at least two hard disks are often linked together using a technology called RAID. This stands for "redundant array of independent disks" (or sometimes "redundant array of inexpensive drives"), and stores the data in each user volume on multiple physical drives.

Many possible RAID configurations are available. The first is called "RAID 0". This divides or "strips" the data in a storage volume across two or more disks, with half of each file written to one disk, and half to another. This improves overall read/write performance without sacrificing capacity. So, for example (as shown above), two 1TB drives may be linked to form a 2TB array. Because this virtual volume is faster than either of its component disks, RAID 0 is common used on video editing workstations.

In contrast to RAID 0, "RAID 1" is primarily intended to protect data against hardware failure. Here data is duplicated or "mirrored" across two or more disks. The data redundancy so created means that if one physical drive fails there is still a complete copy of its contents on another drive. However, this does mean that drive capacity is sacrificed. For example (as shown above), a 1TB RAID 1 volume requires two 1TB disks. While data write performance is not improved by using RAID 1, data read times are increased as multiple files can be accessed simultaneously from different physical drives.

If more than two drives are used, several other configurations become possible. For example, using three of more drives, "RAID 5" strikes a balance between speed and redundancy by stripping data across two drives but also writing "parity" data to a third. Parity data maintains a record of the differences between the blocks of data on the other drives, in turn permitting file restoration in the event of a drive failure. Many modern personal computer motherboards permit two SATA hard disk drives to set up in a RAID configuration. However, for users who do not require the extra speed provided by RAID 0, RAID 5 or RAID 10, there are relatively few benefits to be gained. Not least, it needs to be remembered that any hardware setup featuring more than one internal hard disk -- whether or not in a RAID configuration -- at best provides marginal improvements in data security and integrity. This is simply because it provides no more tolerance to the theft of the base unit, nor to power surges or computer power supply failures (which can simply fry two or more hard drives at once rather than one).

(more will be revealed in this video)

source : explainingcomputers.com

#2 Computer Storage

 Hard Disk Storage

Spinning hard disk (HD) drives are today the most common means of high capacity computer storage, with most desktop and laptop computers still relying on a spinning hard disk to store their operating system, applications programs and at least some user data. Traditional, spinning hard disk drives consist of one or more disk "platters" stacked one above the other, and coated in a magnetic media that is written to and read by the drive heads. As discussed in the hardware section, hard disk drives can transfer data directly to other computer hardware via a range of three interface types (SATA, IDE/UDMA, or SCSI) and come in a range of speeds from 4200 to 15000 revolutions per minute (RPM).

Hard disks are almost always manufactured with either 3.5" of 2.5" platters (although just to break the rule a few smaller -- most notably 1.8" -- and even some larger platter disks are made by some manufacturers). For many years 3.5" hard disks have been standard for desktop computers and servers, and 2.5" hard disks for laptops. Yet this is now starting to change, with enterprise class 2.5" hard disks now increasingly being used in servers and some desktop computers due to their low power requirements. Indeed, the fact that Western Digital's top-of-the-range Velociraptor hard drives now use a 2.5" rather than a 3.5" mechanism speaks volumes and probably indicates that within a few years most spinning hard disk drives are likely to be 2.5". (Note that some raptor models are supplied in a metal "sled" for fitting into a 3.5" bay)

Whilst at least one hard disk is usually required inside a computer as the "system disk", additional hard disk drives can be located either "internally" inside the main computer case, or connected "externally" as an independent hardware unit. A second internal hard disk is highly recommended where a user regularly works on very large media files (typically digital video files) that are always accessed directly off the hard disk, rather than loaded into RAM. Where such files are loaded off a computer's system disk, the disk drive heads are inevitably constantly nipping back and forth between accessing the large media file and writing temporary operating system files, and this both degrades performance and reduces the life of the disk.

source explainingcomputers

#1 Computer Storage

Computer storage is measured in bytes, kilobytes (KB), megabytes (MB), gigabytes (GB) and increasingly terabytes (TB). One byte is one character of information, and is comprised of eight bits (or eight digital 1's or 0's). Technically a kilobyte is 1024 bytes, a megabyte 1024 kilobytes, a gigabyte 1024 megabytes, and a terabyte 1024 gigabytes. This said, whilst this remains true when it comes to a computer's internal RAM and solid state storage devices (like USB memory sticks and flash memory cards), measures of hard disk capacity often take 1MB to be 1,000,000 bytes (not 1,024,768 bytes) and so on. This means that the storage capacity of two devices labelled as the same size can be different, and which remains an ongoing source of debate within the computer industry.

 Any sensible computer user will plan for two categories of storage. These will comprise the storage necessary to keep files internally on their computer, as well as those media required to back-up, transfer and archive data (as also explored in the security section). In turn, when deciding on suitable external storage devices, the key questions to be asked should be how much data actually needs to be stored, and whether the external data archive will be subject to random-access or incremental change.

Storage Capacity And Requirements:

If a computer user is usually only going to create word processor documents and spreadsheets, then most of their files will probably be in the order of a few hundred KB or maybe occasionally a few MB in size. If, however, a computer is being used to store and manipulate digital photographs, then average file sizes will be in the region of several MB in size (and potentially tens of MB if professional digital photography is being conducted). Yet another level of storage higher, if a computer is being used to edit and store video, individual file sizes will probably be measured in hundreds of MB or even a few GB. For example, an hour of DV format video footage consumes about 12GB of storage. Non-compressed video requires even more space -- for example 2GB for every minute of standard definition footage, and 9.38GB for each minute of non-compressed 1920x1080 high definition video. Knowing what a computer is going to be used for (and of course many computers are used for a variety of purposes) is hence very important when planning storage requirements.

In addition to capacity requirements, whether the data in a user's back-up archive will have to change in a random-access or incremental fashion can be a critical factor in the choice of external storage devices. A digital photographer, for example, will probably have incremental back-up requirements where each time they complete a shoot they will want to take a back-up of several hundred MB or a few GB of photographs that will subsequently never change. In other words they will want to keep a permanent record of an historical digital state of the world. Writing data like photographs to write-once media (such as CD-R or DVD-R as discussed below) would hence be perfectly acceptable. The photographer's total archive may be hundreds of GB in size, but would only be added to incrementally with previously stored data never being changed.

In contrast, somebody producing 3D computer animation may be re-rendering tens of GB of output on a regular basis to replace previous files in a random-access fashion. In this situation not only would re-writable media be more suitable, but the speed of the back-up device would become far more critical. Having to take a copy of even 50GB of data at the end of a working day is a very different proposition to a few GB, let alone a few tens or hundreds of MB. Further discussion of the suitability of different media for incremental and random-access back-up continues within the following explanation of available storage devices and technologies.

source: explainingcomputers

What to Look for

source: itsagadget

Antivirus software products block malware from entering your computer system. When security software is unsuccessful at preventing attacks, it is then supposed to detect and remove the malware that gets through the defenses. If you begin to analyze all of the forms of malware and all of the potential entry points, it quickly becomes quite complicated and confusing. You can reduce the complexity of shopping for virus protection by asking a few key questions. How does the antivirus software perform in third-party tests? What features does it have that pertain to my needs? Does it provide support during the times I will need it?

To get some answers, let's discuss these questions one by one.

Performance

The best way to verify vendor claims about performance is to learn how products perform in tests at independent labs. One of the best antivirus researchers is AV-Test, with laboratories in Germany. AV-Test has a lot of credibility within the industry. AV-Test's labs have two dozen servers connected to 280 workstations, where its technicians simulate test environments and perform analysis. They have more than 50 million pieces of malicious test data. Each day, the collection grows by 55,000 new items of malware. The AV-Test suite of tests measures security software's protection, repair and usability components. AV-Test results are the objective criteria we consider when we rank the best antivirus software.

Features

You can usually count on antivirus software to be easy to install and use. You should be able to schedule scans so that they occur when you do not need to use the computer to avoid slowdowns from the software's resource usage requirements. Antivirus software ought to protect you against malware infiltration whether it attempts to reach your computer via web browsing, email, instant messaging or removable storage devices. No security software is perfect, so when a threat successfully accesses your computer, your antivirus software has a second chance to protect you by detecting and disabling the invader.

Help & Support

When you examine help and support, ask yourself whether you will need 24/7 access to technical support or whether you can make do with fewer hours. Some vendors provide support by email. If you want telephone support, use our reviews to learn whether the vendor offers it before you buy.

source: toptenreviews

Combat with Viruses !

source: blogalaxia

Keep the Operating System Updated

The first step in protecting your computer from any malicious there is to ensure that your operating system (OS) is up-to-date. This is essential if you are running a Microsoft Windows OS. Secondly, you need to have anti-virus software installed on your system and ensure you download updates frequently to ensure your software has the latest fixes for new viruses, worms, and Trojan horses. Additionally, you want to make sure your anti-virus program has the capability to scan e-mail and files as they are downloaded from the Internet, and you also need to run full disk scans periodically. This will help prevent malicious programs from even reaching your computer.

Use a Firewall

You should also install a firewall. A firewall is a system that prevents unauthorized use and access to your computer. A firewall can be either hardware or software. Hardware firewalls provide a strong degree of protection from most forms of attack coming from the outside world and can be purchased as a stand-alone product or in broadband routers. Unfortunately, when battling viruses, worms and Trojans, a hardware firewall may be less effective than a software firewall, as it could possibly ignore embedded worms in outgoing e-mails and see this as regular network traffic.

For individual home users, the most popular firewall choice is a software firewall.  A good software firewall will protect your computer from outside attempts to control or gain access your computer, and usually provides additional protection against the most common Trojan programs or e-mail worms. The downside to software firewalls is that they will only protect the computer they are installed on, not a network.

It is important to remember that on its own a firewall is not going to rid you of your computer virus problems, but when used in conjunction with regular operating system updates and a good anti-virus scanning software, it will add some extra security and protection for your computer or network.