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Top 3 Best Free Antivirus Softwares Download

Articles / 2009-09-22

In today’s world having anti-virus software is not optional. A good anti-virus software will perform real-time and on-demand virus (See my another post: Top 10 worst computer viruses) checks on your system, and warn you if it detects a virus. The program should also provide a way for you to update its virus definitions, or signatures; so that your virus protection will be current (new viruses are discovered all the time). It is important that you keep your virus definitions as current as possible.

Antivirus software provides an essential layer of protection from a multitude of virus, trojan, worm, spyware, adware, dialer, keylogger and rootkit infections. Traditionally antivirus softwares just detected virus and spyware removers just detected spyware but nowadays the boundaries between antivirus and spyware removers are unclear. Most current antivirus have at least reasonably good detection rates of all forms of malware.

Pay for antivirus softwares from the biggies Symantec/Norton or Mcafee and it’ll cost roughly £50 per year. Yet you can also take advantage of a variety of decent free softwares, I looked at several free antivirus softwares which are vital in protecting your computer from virus threats and other types of malware.

1. Avira AntiVir Personal – FREE Antivirus

Avira AntiVir Personal is a comprehensive, easy to use antivirus software, designed to offer reliable free of charge virus protection to home-users, for personal use only, and is not for business or commercial use. Available for Windows or UNIX.

// The best free antivirus program, outstanding detection of malware, light on resources
// Quite a few false positives, occasional update problems, advertisements with each update, no e-mail scanning

2. Avast! Home Edition

Free Antivirus represents the best FREE antivirus protection currently available on the market. This edition is FREE OF CHARGE for non-commercial & home use only.

// Good for silent security, full real-time capabilities, fairly light on resources
// Detection rates lower than AntiVir, many false positives, confusing interface

3. AVG Anti-Virus Free Edition

AVG Anti-Virus Free Edition download and installation is only available for single computer use for home and non commercial use.

// Good for silent security, least amount of false positives, e-mail scanning capabilities
// Detection rates lower than AntiVir, limited antirootkit, heavy on resources, installs toolbar by default, advertisements

These three free antivirus softwares are excellent free antivirus programs that provides a real alternative to the major commerical antivirus software.

You can increase your protection if you run on demand scans with another antivirus. On demand scans can be run regularly to check for virus, trojan, worm, spyware, adware, keylogger, rootkit and other malware that may have been missed by your main antivirus scanner. If you have a good preventive security strategy in place, however, the extra protection an on demand antivius scanner offers is minimal.

You can also use one of the free antivirus programs mentioned above as an on-demand antivirus scanner. One advantage is that you can set scheduled scans if you wish.

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Computer Data Storage Types And Data Storage Devices

Articles / 2009-09-21 / 1 Comment

With the increasing use of technology, usage of digital data has increased to no limits. In order to store this enormous amount of data, we need more powerful and secured data storage devices. Development teams all over the world are working around the clock to make better devices which would be small and inexpensive, but at the same time having more capacity and security.

These are the types of data storage used in computers. Advancing technologies these days are increasing the access rate and the capacity of these data storage devices.

Computer Data Storage Types

1. Data Storage Types – Primary Storage
Basically, primary storage is the memory part of the computer itself. Primary storage includes the Random Access Memory (RAM) and Read Only Memory (ROM).

2. Data Storage Types-Secondary Storage
Hard disks, magnetic tapes and all other data storage devices are included in the secondary storage. They are external to the processor and are used to increase the storage capacity of the computer. The secondary storage is non-volatile and can retain information even after the computer is switched off.

3. Data Storage Types – Tertiary Storage
Tertiary data storage is the third data storage out of the three types of data storage. The tertiary devices includes the storage devices that are connected to the computer in the form of removable mass storage devices. Tertiary storage is often used to store those files that are rarely accessed by the computer user.

Computer Data Storage Devices

Computer data storage devices refers to computer components which can retain the data in digital format, to be used for computing at some point of time in the future.

Disk Storage
Disk storage is a category of computer storage devices, wherein the data is recorded on a round and rotating surface, two-dimensional in nature. Disk drivers are used to record or retrieve information from these disks. Though these days, the term disk storage is mostly used to refer to a hard disk, it also refers to floppy disks and optical disks.

Floppy Disk
A floppy disk is a thin flexible medium of magnetic storage which is encased in a square plastic shell. A floppy disk is read and written by a floppy disk drive. This small storage device was invented by IBM in 1969. It comes in three sizes – 8-inch, 5¼-inch and 3½-inch. Floppy disks enjoyed wide popularity from the 70s to the 90s, but post 90s they were overshadowed by devices which had more capacity and were faster. The use of floppies has almost ceased, though limited use can be still seen in some places.

Compact Disk
Compact disk, more commonly referred to as a CD, is an optical disk used to store digital data. After its introduction in the market in 1982, this technology was followed with the launch of CD-ROM, CD-R, CD-RW, VCD, SVCD and Enhanced CD. CD-ROM and CD-R are widely used in the field of computers. A standard CD having a diameter of 120 mm can hold up to 700 MB data. An estimated 200 billion CDs were sold all over the world by the year 2007.

Digital Versatile Disk
Digital versatile disk, more commonly referred to as DVD, is an optical storage device used for data storage in computer technology. Although they share the same dimensions as the CDs, DVDs have the capacity to store six times more data than the compact disks. DVD-video is used to store video content while DVD-audio is used to store audio content. The original DVD is more often referred to as Standard Definition DVD (SD-DVD). High-definition DVDs were discontinued after the Blu-ray optical disk was introduced into the market.

Blu-Ray Disks
Blu-ray disks, also referred to as BD, are optical disks manufactured by Sony for the storage of digital data. Its is most commonly used in gaming, high definition video storing, etc. Though it is of the same size as a CD or DVD, it can store up to 50 GB data. This technology uses a blue-violet laser to read the data, and hence is referred to as blu-ray disk. These optical disks have overshadowed other optical storage devices due to their high storage capacity.

Hard Disk Drive
A hard disk drive is a non-volatile storage device used to store digitally encoded data on rotating platters having magnetic surfaces. Being non-volatile means it can retain the data stored on it even when it is not powered. Hard disk drives were invented by an IBM team, led by Rey Johnson on 14th December, 1954. Earlier, hard disk drives were a removable form of data storage, but today it has become a sealed unit with fixed media. The first hard disk had a capacity to store 5 MB data on fifty 24 inch platters. Today, the capacity has risen to more than a 100 gigabytes, and is still increasing by the day.

Flash Memory
Flash memory is a non-volatile memory in computer technology which can be electrically programmed or erased. Flash memory devices commonly used today include USB flash drives and memory cards.

USB Flash Drive
USB flash drive is a type of memory storage device that consists of NAND-type flash memory, integrated with Universal Serial Bus (USB) interface. The USB flash drives are removable as well as rewritable. Although they are smaller than a floppy disk, their storage capacity ranges from 64 MB to 128 GB. Some USB drives allow as many as 1 million erases and write cycles, while some have a 10 year data retention capacity.

Memory Cards
Flash memory cards are solid electronic flash memory devices used to store data in digital format. These cards are often used in hand-held as well as mobile computers. They are rewritable and non-volatile in nature. Though small, they have a high capacity and can store data of around 8 GB or more.

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Top 5 Online Backup Service: Mozy

Articles / 2009-09-21

Mozy is a simple and safe way to back up all the important stuff on your computer. A copy of your data is stored in a secure, remote location for safekeeping, so that in the event of disaster your data is still retrievable.

How Mozy Works?

Sign up for an account.
Create a MozyHome user account which will allow you to download MozyHome software. Its quick, easy and our step-by-step instructions will guide you through the process.
Download and install software.
MozyHome downloads in just seconds, and the installation is simple and fast.
Select files to be backed up.
Simply check the boxes next to the backup sets, or types of files you want to back up, and MozyHome does the rest. In addition to selecting files by backup sets, you also have the option of selecting specific files and directories.

Free to try (Home Users)
No setup fee, no monthly payments, no credit cards, no hassle. Sign Up Now (Hot!)

Customer Reviews:

1. “I prefer Mozy.”
Walter S. Mossberg, The Wall Street Journal

2. “MozyHome is excellent value.”
Ben Pitt, Computer Shopper

3. “Best For Automatic Backup: Mozy”
Mark Spoonauer, Inc.com

4. “The MozyHome Unlimited offering gets a nod for best value”
RickVanover, NotebookReview.com

5. “Since [implementing MozyPro], the solution has saved the school 75 percent in backup costs.”
Bridget McCrea, Campus Technology

Mozy Price:
MozyHome Unlimited is for personal, non-commercial use only. Business users check out MozyPro.

MozyHome: Each computer costs $4.95/month (MozyHome)
MozyPro: Desktop Licenses: $3.95 + $0.50/GB per month
MozyPro: Server Licenses: $6.95 + $0.50/GB per month

Accounts can be billed monthly, annually, or biennially. You can get one month FREE when you sign up for an annual account or three months FREE with a biennial subscription.

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Backup Now! Free Backup Softwares Roundup

Articles / 2009-09-20

Freeware backup software is finally becoming more common — perhaps because of the explosion of large storage devices. Whatever backup option you choose, make sure you choose one and get started early. You can always use another backup method later as your needs grow. The tools below are some of my favorite free backup softwares.

Free Backup Softwares:

Autobackup: is considered to be one of the best no-frills freeware tool for backup. You need a create a list of paths that have to be checked and a backup mirrored copy is created of all the files that are found in those files and have been modified since the last backup.
TaskZip: is a small little tool that runs as a system agent. It automatically archives all specified files and folders into a single zip file. You can also specify a password for the zip file. Unfortunately, this tool does not provide the feature of restoration.
Lou Backup: is a very easy to use backup tool that is meant to backup Visual C source code files but can also be used to backup folder structures. It also supports the backup of multiple projects, directories and provides features of folder exclusion and backup of only modified files.
Comparator: is optimized for use on a single computer and provides the feature of folder monitoring and data synchronization. Although the data backup and data restore features are excellent, the amount of input it requires is a little more than desirable.
NTI BackupNow: has an excellent user interface when compared to most of the freeware tools. The only drawback of this tool is that you will have to specify the exact location of the files that you need to copy. For example, there is no option of selecting that you need a backup of your emails. You will have to provide the path of your PST or any equivalent file. Further, no encryption is present; hence it may not be suitable for some users.
Genie Backup Manager: is a very fast tool that is capable of backing up the Windows registry, favorites, Outlook data and other system files along with all regular data. The latest version of the tool has a disaster recovery option that allows the user to backup and restore the Windows Operating System along with all the data. As per a review that I was reading, there as are so many flexible options available, it ends up confusing the users!
SyncBack: is the freeware version of the commercial backup software ‘SyncBackSE’ and does not require installation. This tool can take all kinds of backups and also features a built in FTP engine which can store the backed up data on an FTP site. However, there are few features like network optimization which are disabled due to the fact that this is a freeware.
EASEUS Todo Backup: can backup your system partition to quickly get the system up and running in the event of a system crash or hardware failure. It allows you to backup and restore disks or partitions after viruses a attack, unstable software crash, hard drive failure, etc. It is also useful when you want to upgrade an older smaller hard drive without reinstalling the operating system and applications.

One great idea that I think will become commonplace soon is that of remote backup or online backup.

Remote Backup Softwares
Remote backup software work like any regular backup software. The important difference is that instead of storing the backup on a tape drive or a separate location, these softwares send the backup over the Internet or Intranet to online backup servers. The backup can be scheduled during the time frame when the computer is not in use. The entire process is completely automated and most employees do not even realize that such a process is in place. These kinds of backups are usually a part of the disaster recovery plan of large organizations.

Depending on your needs and the needs of your organization, it is very vital that you have a scheduled backup process in place. For some of us, the data that is stored in the computers help us earn our daily bread and water and there is no way to afford the loss of the data. If your organization is a little big in size and can afford a licensed version of a backup software, then it is more advisable as you will also receive all the newer versions and patches when you purchase the software. Backup your data and sleep soundly.

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Usb Flash Drive Data Recovery

Articles / 2009-09-19

USB flash drives have become one of the major sources of data transferring sources since 2000. And along with this, the rate of data failure due to virus attacks and device failures is also increasing day by day. Many data recovering software products are available in the market but due to the lack of knowledge and mishandling even a simple recovery becomes a nightmare for the user.

Many a time we lose important information from the USB flash drive by accident. Find out here how to do a USB Flash Drive Data Recovery by using some simple methods.

Most of us use the USB (Universal Serial Bus) flash drive for storing necessary data that has to be transferred from one system to another. A USB flash drive is an external data storage device that allows the user to store data temporarily. This data can be transferred from one system to another by connecting the flash drive to a particular system’s external hard drive port, i.e. the USB port. A USB flash drive is popularly known as a pen drive. It is a very convenient and handy device but sometimes the USB flash drive fails to operate due to some unknown reasons. Given below are some methods for USB flash drive recovery.

Tips for USB Flash Drive Data Recovery

Many times your USB flash drive does not open when you click on the icon that appears in the windows browser after you connect the USB flash drive to the USB port of the CPU. This may happen if the USB drive is corrupted or if some computer virus has entered the drive. In such cases, the first thing to try is to right click and select Open/Explore.

If neither of the two options work, then try scanning the drive with an antivirus software. If the pen drive is not working due to virus, scanning the pen drive with an effective antivirus is a good option for USB flash drive data recovery and can restore the USB.

If scanning also does not help, the only option left is to format the drive. Formatting will erase all the files from the drive, therefore, before formatting, create a backup of all your important files. To format the drive, right click on the drive icon, select format, select quick format option on the format window, follow the ‘prompt’ messages (something like a warning message saying that ‘if you format your drive, all the data stored in it will be lost’), select OK or Cancel (this will stop the format process). The quick format takes few minutes, depending on the size of the data to be erased. Once the formatting is done, your USB will become as good as new and you can use it as before.

Well, I hope you know how to format your computer ’cause sometimes even this option fails and you have to format the flash drive in a more tedious way. For this method, you will need a bootable CD (compact disk) of your operating system. Restart your desktop computer after you have inserted the bootable operating system CD in the CD drive and let the USB flash drive be connected to the USB port. When the computer is restarting, press F8/F2/Del key (depending on your configuration) immediately. Browse to the booting configuration options and change the first bootable device to your CD drive. Now, save the changes and restart your computer. Your PC will start booting from the CD and the installation process will begin. Follow the ‘prompt’ messages till the point where the window will display the names and sizes of all the existing drives. Here you have to select the drive indicating your USB drive and select format option. The USB will get formatted. Now, if you want to continue with the installation process, go ahead, else repair the existing operating system or you can quit. Be assured your flash drive will be formatted and will work fine.

If the matter is more serious than this, search for the warranty card (hope you can find it and hope the warranty period is not expired) and take the USB flash drive straight to the dealer.
That was a brief about the methods of USB flash drive data recovery. However, to avoid any of the above situations, treat your USB flash drive well. Do not remove the drive without stopping it. Always go to the lower right side of your screen on the taskbar where a green arrow appears after you have connected the USB, click on it and click on your USB flash drive name. Only after the message ‘Remove Drive Safely’ appears, physically remove your USB drive, else go to the icon of the USB drive, right click on it and select ‘Eject’. Also, never remove the USB while some data transfer is going on from a computer to USB or vice-versa. Doing so may corrupt your data. Never leave any file or folder of the USB open when you want to disconnect or remove the USB flash drive. This can also cause some serious problems to the data as well as to the drive.

Hope the above USB flash drive data recovery methods will help you in your attempts at repairing your USB! And if you have any experiences or additional methods of repairing the USB, please feel free to share them here.

Data recovery handled professionally is the best solution for any kind of data loss from your pen drive, hard drive, memory stick or any other storage device. A systematic scan of the damaged device is essential for starting the right type of action for each attempt at data recovery. Depending on your file system combination, the drives operating system and document types there are different ways to handle data loss.

It is always best to consult with expert guidance for scanning and determining your data loss type and severity because even a minor mistake can permanently erase your files and data forever.

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How to recover and fix corrupt files?

Articles / 2009-09-19 / 1 Comment

When you try to open a particular file and it shows an error displaying ‘cannot open file’ or ‘file data inaccessible’, you need to understand that the file has been corrupted. The file is also corrupted if it is accessible, but the content is displayed as some symbols instead of numbers and alphabets.

Recovering corrupt files is the only way if you want to save your important files which have been corrupted due to some or the other reasons. If you are thinking how to recover corrupt files, the below post will inform you more on the process.

How to Recover and Fix Corrupt Files?
1. Recovery of Word Files
The files which are opened through the MS Word application are known as word files. These files may contain some important or confidential text data, and if they are corrupted their repair is absolutely necessary. If you have a word file that has to be recovered, you need to utilize a word repair application which can easily be downloaded from the Internet. Such software have easy-to-use interfaces and operating instructions, and you will not at all find it difficult to execute the file recovery procedure. Examples of word document repair software are Repair MyWord, Nucleus Kernel Word Document Repair Software, etc. Repair MyWord can be downloaded free of cost and it provides an easy interface for the retrieval of files.

2. Recovery of Media Files
There are many types of media files that we normally store on the hard drive, such as .avi, .dat, .mp4, .mpeg3, etc. As other document, image, and program files; these files may also get corrupted. The typical way of recovering media files is to use certain software. There are many applications which repair corrupted files of all media such as mp3, mp4, avi, dat, wmv, and so on. The operation of these applications is very simple. You just need to open the software, press the browse button, select the corrupted file which is to be repaired, and select the repair option.

3. Recovery of Zip Files
These are compressed forms of files which have huge memory sizes. Files which are very large in memory size are normally compressed using specific software, particularly if they have to be sent via email. If you want to recover the corrupted zip files, the process is the same of using a recovery software application. Zip Repair Software, Zip Repair Tool, and Actual Zip Repair are some of the applications that help in this type of file recovery.

4. Recovery of JPEG/ JPG Files
This type of file contains a photo or a picture. When a JPEG file does not open in any of the default programs such as Paint, Windows Photo Gallery, Fax Viewer, and some others; it is to be considered corrupted. If the file turns corrupt, you are unable to view the picture. You initially need to try retrieving the file by renaming and saving it with a .jpg file extension. If this does not work, the next step would be to take aid of some JPEG image recovery applications. JPEG Recovery and Picture Doctor are some of the applications which can be used in repairing corrupted JPEG files.

5. Recovery of Corrupt Files on PSP

First and foremost, check if the file you are trying to open in your PSP (PlayStation Portable) is compatible with the PSP file format or not. If your PSP does not support the file format, you may have to convert the file to the file format supported by your PSP. A direct method to repair the corrupted file is, to connect the PSP to the computer and run the data recovery software on your PC. Include the files on the PSP in the recovery software and retrieve them. If that is not possible then, put the corrupted files back on your computer, recover the files using a recovery tool for that file format and put it back on the PSP.

When it comes to saving important files, it is always recommended to keep a backup in any data storage device. This will surely enable you to have a copy of the original file which has gone corrupt. Moreover, there are several data recovery software that are available for download on the Internet. If these applications are not free of charge, you always have the option of downloading a free version temporarily just to recover corrupted files.

Some of the data recovery software may not be available free of cost. If they are not freeware then you can download a trial or demo version to repair your files. Also remember, a software that works for someone else may not necessarily work for you. Hence, you may have to employ the trial and error method to check the validity of the software. In case if a virus, you may need to run an antivirus software, after which the corrupted files may open. In case of hardware failure, hard drive data recovery is also possible. Hope the above methods will answer your questions about how to fix corrupt files!

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Top 5 Online Backup Services

Articles / 2009-09-18 / 4 Comments

Where’s the best place to keep your data? Online backup services will keep your data safe no matter what sort of disaster strikes your local computers. Online backup services work much like regular backup software. With an online backup service, however, your important data is transmitted over the Internet and securely stored on a server in a professional data center instead of being stored on your own CDs, DVDs, or backup tapes. Most of us still waste time doing this manually which means we often don’t have a backup of our most recent work.

Ten of the top choices for online backup service are:

1. Mozy

Mozy offers reasonably priced unlimited online backup that’s highly configurable, but it could stand some usability improvements.

2. Carbonite

Carbonite tries to make remote backup simple and affordable. Setting it up is a breeze, and restoring a file here or there is also a snap. But restoring a lot of data to a different PC presented some obstacles.

3. SOS Online Backup

This is another backup service that offers a lot of additional features for those users who want to do a lot with the service. It tends to be more user-friendly than IDrive according to most people, though, so you may find that it’s the better of the two choices if you’re just starting out and aren’t quite confident in your own tech-savvy skills. It’s received numerous awards so it’s certainly a good choice.

4. IDrive

There are several reasons that you might enjoy this backup service. It’s got some storage offered entirely for free so it’s great if you’re just starting to figure out whether online backup is even for you or not. It’s also got a lot of great additional features (like advanced search functions and drag-and-drop restoration) that can be used by people who do already like online backup and who want to be able to do more with it.

5. HP Upline

This easy-to-use, reasonably priced online backup service also lets you do local media backups and file sharing, but it lacks important features, like version saving, open-file backup, and the ability to resume interrupted file uploads

The type of online backup service that you want to get is really going to depend a lot on what you need it for. If you’re storing a lot of media then you want a service with a lot of storage. If you’re storing documents that you share with others then you want a backup service that has collaboration features. These five choices are a good place to start in your search for online backup options.

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The Best Online Backup Service Is The One That Fits Your Needs

Articles / 2009-09-17

Where’s the best place to keep your backed-up data? Somewhere far, far away. Online backup services will keep your data safe no matter what sort of disaster strikes your local PCs.

Backing up your files online is a safe alternative to using regular backup software. However, finding the best online backup service to use isn’t as easy. This post will help you choose the best online backup provider that will be easy on your pocket book and provide the services you want.

Backing up your computer, or choosing an online backup service, is one of the most important things you do to insure data and files are not compromised or terminally lost during unforeseen “disasters,” which, according to “Murphy,” can, and probably will, happen at some point.

How do you shop for the best online backup service for you? How much space do your files need? How many user accounts do you have? Who can you trust with your data privacy? How much can you afford?

Security
Companies advertising more than one data center offer simultaneous duplicate backups of your data. Look for warnings from companies about your passkey. They will tell you if you lose your passkey, you cannot access your data backup account. This is a good thing! It lets you know that no one can randomly access your backup account without your permission or passkey.

Frequency
More is better. You want to get multiple copies of your data, automatically uploaded on a frequent and regular basis. The more often your data is backed up, the more protection you have in the event of a virus or irreparable corruption.

Space
Do you save lots of pictures, videos, and music? These files consume a lot of space and it might be more efficient to use an external hard drive to backup these. However, external and optical drives do not offer privacy and protection afforded by online (remote) backup services.

Price
“You get what you pay for.” Typically low-cost services take longer to complete the initial backup. They reduce their bandwidth costs by slowing your upload speed, which limits the amount of data that can be backed up, thus taking for, what can seem like forever, when you want to get done with maintenance and resume your processing.

Free Trial
If you have a high-speed Internet connection, and know what you want to back up and where the files are located, there are online backup services that allow you to try their service for free on a trial basis.

The best online backup service is the one that fits your needs and pocketbook.

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How NTFS File System Works: NTFS Physical Structure (6)

Articles / 2009-09-17

Last Access Time

Each file and folder on an NTFS volume contains an attribute called Last Access Time. This attribute shows when the file or folder was last accessed, such as when a user performs a folder listing, adds files to a folder, reads a file, or makes changes to a file. The most up-to-date Last Access Time is always stored in memory and is eventually written to disk within two places:

The file’s attribute, which is part of its MFT record.
A directory entry for the file. The directory entry is stored in the folder that contains the file. Files with multiple hard links have multiple directory entries.

The Last Access Time on disk is not always current because NTFS looks for a one-hour interval before forcing the Last Access Time updates to disk. NTFS also delays writing the Last Access Time to disk when users or programs perform read-only operations on a file or folder, such as listing the folder’s contents or reading (but not changing) a file in the folder. If the Last Access Time is kept current on disk for read operations, all read operations become write operations, which impacts NTFS performance.

Note: File-based queries of Last Access Time are accurate even if all on-disk values are not current. NTFS returns the correct value on queries because the accurate value is stored in memory.

NTFS eventually writes the in-memory Last Access Time to disk as follows.

Within the file’s attribute

NTFS typically updates a file’s attribute on disk if the current Last Access Time in memory differs by more than an hour from the Last Access Time stored on disk, or when all in-memory references to that file are gone, whichever is more recent. For example, if a file’s current Last Access Time is 1:00 P.M., and you read the file at 1:30 P.M., NTFS does not update the Last Access Time. If you read the file again at 2:00 P.M., NTFS updates the Last Access Time in the file’s attribute to reflect 2:00 P.M. because the file’s attribute shows 1:00 P.M. and the in-memory Last Access Time shows 2:00 P.M.

Within a directory entry for a file

NTFS updates the directory entry for a file during the following events:

When NTFS updates the file’s Last Access Time and detects that the Last Access Time for the file differs by more than an hour from the Last Access Time stored in the file’s directory entry. This update typically occurs after a program closes the handle used to access a file within the directory. If the program holds the handle open for an extended time, a lag occurs before the change appears in the directory entry.
When NTFS updates other file attributes such as Last Modify Time, and a Last Access Time update is pending. In this case, NTFS updates the Last Access Time along with the other updates without additional performance impact.

Note: NTFS does not update a file’s directory entry when all in-memory references to that file are gone.

If you have an NTFS volume with a high number of folders or files, and a program is running that briefly accesses each of these in turn, the I/O bandwidth used to generate the Last Access Time updates can be a significant percentage of the overall I/O bandwidth.

Multiple Data Streams

A data stream is a sequence of bytes. An application populates the stream by writing data at specific offsets within the stream. The application can then read the data by reading the same offsets in the read path. Every file has a main, unnamed stream associated with it, regardless of the file system used.

However, NTFS supports additional named data streams in which each data stream is an alternate sequence of bytes as illustrated in the figure Unnamed and Named Streams. Applications can create additional named streams and access the streams by referring to their names. This feature permits related data to be managed as a single unit. For example, a graphics program can store a thumbnail image of bitmap in a named data stream within the NTFS file containing the image.

Unnamed and Named Streams

FAT volumes support only the main, unnamed stream, so if you try to copy or move Streamexample.doc to a FAT volume or floppy disk, you receive an error message.

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How NTFS File System Works: NTFS Physical Structure (5)

Articles / 2009-09-17

NTFS File Record Attributes

Every allocated sector on an NTFS volume belongs to a file. Even the file system metadata is part of a file. NTFS views each file (or folder) as a set of file attributes. File elements such as its name, its security information, and even its data are file attributes. Each attribute is identified by an attribute type code and an optional attribute name.

File and folder records are 1 KB each and are stored in the MFT, the attributes of which are written to the allocated space in the MFT. Besides file attributes, each file record contains information about the position of the file record in the MFT.

When a file’s attributes can fit within the MFT file record for that file, they are called resident attributes. Attributes such as file name and time stamp are always resident. When the amount of information for a file does not fit in its MFT file record, some file attributes become nonresident. Nonresident attributes are allocated one or more clusters of disk space. A portion of the nonresident attribute remains in the MFT and points to the external clusters. NTFS creates the Attribute List attribute to describe the location of all attribute records. The table NTFS File Attribute Types lists the file attributes currently defined by NTFS.

NTFS File Attribute Types

Attribute Type	Description
Standard Information	Information such as access mode (read-only, read/write, and so forth) timestamp, and link count.
Attribute List	Locations of all attribute records that do not fit in the MFT record.
File Name	A repeatable attribute for both long and short file names. The long name of the file can be up to 255 Unicode characters. The short name is the 8.3, case-insensitive name for the file. Additional names, or hard links, required by POSIX can be included as additional file name attributes.
Data	File data. NTFS supports multiple data attributes per file. Each file typically has one unnamed data attribute. A file can also have one or more named data attributes.
Object ID	A volume-unique file identifier. Used by the distributed link tracking service. Not all files have object identifiers.
Logged Tool Stream	Similar to a data stream, but operations are logged to the NTFS log file just like NTFS metadata changes. This attribute is used by EFS.
Reparse Point	Used for mounted drives. This is also used by Installable File System (IFS) filter drivers to mark certain files as special to that driver.
Index Root	Used to implement folders and other indexes.
Index Allocation	Used to implement the B-tree structure for large folders and other large indexes.
Bitmap	Used to implement the B-tree structure for large folders and other large indexes.
Volume Information	Used only in the $Volume system file. Contains the volume version.

NTFS creates a file record for each file and a folder record for each folder created on an NTFS volume. The MFT includes a separate file record for the MFT itself. These file and folder records are 1 KB each and are stored in the MFT. The attributes of the file are written to the allocated space in the MFT. Besides file attributes, each file record contains information about the position of the file record in the MFT. The figure MFT Entry with Resident Record shows the contents of an MFT record for a small file or folder. Small files and folders (typically, 900 bytes or smaller) are entirely contained within the file’s MFT record.

MFT Entry with Resident Record

Typically, each file uses one file record. However, if a file has a large number of attributes or becomes highly fragmented, it might need more than one file record. If this is the case, the first record for the file, the base file record, stores the location of the other file records required by the file.

Folder records contain index information. Small folder records reside entirely within the MFT structure, while large folders are organized B-tree structures and have records with pointers to external clusters that contain folder entries that cannot be contained within the MFT structure.

The benefit of using B-tree structures is evident when NTFS enumerates files in a large folder. The B-tree structure allows NTFS to group, or index, similar file names and then search only the group that contains the file, minimizing the number of disk accesses needed to find a particular file, especially for large folders. Because of the B-tree structure, NTFS outperforms FAT for large folders because FAT must scan all file names in a large folder before listing all of the files.

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