Cloud

Cloud

The term  "cloud"  comes from early network diagrams, in which the image of a cloud was used to indicate a large network, such as a WAN. The cloud eventually became associated with the entire Internet, and the two terms are now used synonymously. The cloud may also be used to describe specific online services, which are collectively labeled "cloud computing."

Examples of popular cloud-based services include web applications, SaaS, online backup, and other types of online storage. Traditional Internet services like web hosting, email, and online gaming may also be considered part of the cloud since they are hosted on Internet servers, rather than users' local computers. Even social networking websites such as Facebook and LinkedIn are technically cloud-based services, since they store your information online.

While "the cloud" is simply a buzzword for most consumers, it plays an important role for businesses. By moving software services to the cloud, companies can share data more efficiently and centralize their network security. Additionally, cloud-based virtualization can help businesses reduce the number of computer systems and software licenses they need to buy. The end result and a more efficient and less costly way of running a business.

Access Control List (ACL)

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    An access control list (ACL) is a table that tells a computer operating system which access rights each user has to a particular system object, such as a file directory or individual file. Each object has a security attribute that identifies its access control list. The list has an entry for each system user with access privileges. The most common privileges include the ability to read a file (or all the files in a directory), to write to the file or files, and to execute the file (if it is an executable file, or program). Microsoft Windows NT/2000, Novell's NetWare, Digital's OpenVMS, and UNIX-based systems are among the operating systems that use access control lists. The list is implemented differently by each operating system.

In Windows NT/2000, an access control list (ACL) is associated with each system object. Each ACL has one or more access control entries (ACEs) consisting of the name of a user or group of users. The user can also be a role name, such as "programmer," or "tester." For each of these users, groups, or roles, the access privileges are stated in a string of bits called an access mask. Generally, the system administrator or the object owner creates the access control list for an object.

Cloud Computing

Cloud computing refers to applications and services offered over the Internet. These services are offered from data centers all over the world, which collectively are referred to as the "cloud." This metaphor represents the intangible, yet universal nature of the Internet.

The idea of the "cloud" simplifies the many network connections and computer systems involved in online services. In fact, many network diagrams use the image of a cloud to represent the Internet. This symbolizes the Internet's broad reach, while simplifying its complexity. Any user with an Internet connection can access the cloud and the services it provides. Since these services are often connected, users can share information between multiple systems and with other users.

Examples of cloud computing include online backup services, social networking services, and personal data services such as Apple's MobileMe. Cloud computing also includes online applications, such as those offered through Microsoft Online Services. Hardware services, such as redundant servers, mirrored websites, and Internet-based clusters are also examples of cloud computing.

Understanding SCSI, ATA, SAS and SATA

The Differences Between Parallel and Serial Interfaces

For years the parallel interface has been widely used in storage systems. The need for increased bandwidth and flexibility in storage systems made the SCSI and ATA standards an inefficient option. A parallel interface is a channel capable of transferring date in parallel mode — that is transmitting multiple bits simultaneously. Almost all personal computers come with at least one parallel interface. Common parallel interfaces include SCSI and ATA.

SCSI

Short for small computer system interface, a parallel interface standard used by Apple Macintosh computers, PCs and many UNIX systems for attaching peripheral devices to computers. Nearly all Apple Macintosh computers, excluding only the earliest Macs and the recent iMac, come with a SCSI port for attaching devices such as disk drives and printers. SCSI interfaces provide for data transmission rates (up to 80 megabytes per second). In addition, you can attach multiple devices to a single SCSI port, so that SCSI is really an I/O bus rather than simply an interface.

ATA

(Also known as IDE) is a disk drive implementation that integrates the controller on the disk drive itself. ATA is used to connect hard disk drives, CD-ROM drives and similar peripherals and supports 8/16-bit interface that transfer up to 8.3MB/s for ATA-2 and up to 100MB/s (ATA-6).

So, what do parallel interfaces have to do with SAS (Serial Attached SCSI) and SATA (Serial ATA)? A lot, actually. It is the architectural limitations of the parallel interfaces that serial technologies like SAS and SATA address. In contrast to multiple parallel data stream, data is transmitted serially, that is in a single steam, by wrapping multiple bits into packets and it is able to move that single stream faster than parallel technology.

Serial Attached SCSI (SAS)

Abbreviated as SAS, Serial Attached SCSI, an evolution of parallel SCSI into a point-to-point serial peripheral interface in which controllers are linked directly to disk drives. SAS is a performance improvement over traditional SCSI because SAS enables multiple devices (up to 128) of different sizes and types to be connected simultaneously with thinner and longer cables; its full-duplex signal transmission supports 3.0Gb/s. In addition, SAS drives can be hot-plugged.

Serial ATA (SATA)

Often abbreviated as SATA, Serial ATA is an evolution of the Parallel ATA physical storage interface. Serial ATA is a serial link — a single cable with a minimum of four wires creates a point-to-point connection between devices. Transfer rates for Serial ATA begin at 150MB/s.

Starting with SATA, it extends the capabilities of ATA and offers transfer rates starting at 150MB/s and, after years of development, has moved to the mainstream of disk interfaces. The successor the SCSI interface is SAS at speeds of up to 3Gb/s. Additionally, it also addresses parallel interface issues such as drive addressability and limitations on the number of device per port connection.

SAS devices can communicate with both SATA and SCSI devices (the backplanes of SAS devices are identical to SATA devices). A key difference between SCSI and SAS devices is the addition in SAS devices of two data ports, each of which resides in a different SAS domain. This enables complete failover redundancy. If one path fails, there is still communication along a separate and independent path.

Cables & Connectors

Another big advantage of SATA over ATA is the cabling and connectors. The serial interface reduces the amount of wires needed to transmit data, making for much smaller cable size and making it easier to route and install SATA devices. The IDE cables used in parallel ATA systems are bulkier than Serial ATA cables and can only extend to 40cm long, while Serial ATA cables can extend up to one meter. In addition to the cabling, a new design of connectors is also used that reduces the amount of crosstalk between the wires, and the connector design also provides easier routing and better air flow.

The Benefits of SAS & SATA in Storage

Serial interfaces offer an improvement over older parallel SCSI (with a serial version) in storage applications and environments. These benefits include better performance, better scalability, and also better reliability as the parallel interfaces are at their limits of speed with reliable data transfers. SAS and SATA drives can also operate in the same environment while SCSI and ATA cannot. For example, using faster SAS drives for primary storage and offloading older data to cheaper SATA disks in the same subsystem, something that could not be achieved with SCSI and ATA.

What are Cookies and What Do Cookies Do?

The name cookie derives from UNIX objects called magic cookies. These are tokens that are attached to a user or program and change depending on the areas entered by the user or program. OR;;

A cookie is the term given to describe a type of message that is given to a Web browser by a Web server.  The main purpose of a cookie is to identify users and possibly prepare customized Web pages or to save site login information for you.
When you enter a Web site using cookies, you may be asked to fill out a form providing personal information; like your name, e-mail address, and interests. This information is packaged into a cookie and sent to your Web browser, which then stores the information for later use. The next time you go to the same Web site, your browser will send the cookie to the Web server. The message is sent back to the server each time the browser requests a page from the server.

A Web server has no memory so the hosted Web site you are visiting transfers a cookie file of the browser on your computer's hard disk so that the Web site can remember who you are and your preferences. This message exchange allows the Web server to use this information to present you with customized Web pages. So, for example, instead of seeing just a generic welcome page you might see a welcome page with your name on it.

Types of Cookies

session cookie
Also called a transient cookie, a cookie that is erased when you close the Web browser. The session cookie is stored in temporary memory and is not retained after the browser is closed. Session cookies do not collect information from your computer. They typically will store information in the form of a session identification that does not personally identify the user.

persistent cookie 
Also called a permanent cookie, or a stored cookie, a cookie that is stored on your hard drive until it expires (persistent cookies are set with expiration dates) or until you delete the cookie. Persistent cookies are used to collect identifying information about the user, such as Web surfing behavior or user preferences for a specific Web site.


What Information Does a Cookie Store?
For the most part a cookie will contain a string of text that contains information about the browser. To work, a cookie does not need to know where you are from, it only needs to remember your browser. Some Web sites do use cookies to store more personal information about you. However, this can be done only if you yourself have provided the Web site with that personal information. Legitimate Web sites will encrypt this personal information stored in the cookie to prevent unauthorized usage by another party with access to your cookie folder.

Cookies have six parameters that can be passed to them:

Ø  The name of the cookie.
Ø  The value of the cookie.
Ø  The expiration date of the cookie - this determines how long the cookie will             remain active in your browser.
Ø  The path the cookie is valid for - this sets the URL path the cookie us valid in.         Web pages outside of that path cannot use the cookie.
Ø  The domain the cookie is valid for. This makes the cookie accessible to pages on     any of the servers when a site uses multiple servers in a domain.
Ø  The need for a secure connection - this indicates that the cookie can only be           used under a secure server condition, such as a site using SSL.



What are Malicious Cookies?
Cookies normally do not compromise security, but there is a growing trend of malicious cookies. These types of cookies can be used to store and track your activity online. Cookies that watch your online activity are called malicious or tracking cookies. These are the bad cookies to watch for, because they track you and your surfing habits, over time, to build a profile of your interests. Once that profile contains enough information there is a good chance that your information can be sold to an advertising company who then uses this profile information to target you with interest specific adverts. Many antivirus programs today will flag suspicious spyware or adware cookies when scanning your system for viruses.



First and Third-Party Cookies
When choosing a privacy setting in your browser, two terms you will see are "first-party cookies" and "third-party cookies". First party cookies are those cookies that originate from (or be sent to) the Web site you're currently viewing. These types of cookies usually will contain information about your preferences for that particular Web site. These cookies are usually Third-party cookies originate from (or will be sent to) a Web site that is not the site you are visiting. For example, if the Web site you are on using third-party advertising those third-party advertising Web sites may use a cookie to track your Web habits for marketing purposes.

While some may simply choose to block all cookies, it can make Web surfing difficult if you do this. For example if you shop online, many e-commerce shopping carts that have been implemented with cookies will not work. Sites you frequently visit which enable you to personalize content also will not show your preferences when you visit if you delete or disable that cookie.

Most cookies, despite some misconceptions, are legitimate files and will not invade your privacy. Once you get in the habit of reviewing the cookies associated with your browser and manage them on your own by way of deleting malicious cookies or trying different browser privacy settings, you can still keep the good cookies that make surfing a breeze, yet keep the bad cookies that may be tracking your surfing habits off your system.

Viewing & Removing Cookies

Cookies are stored by the Web browser on your system's hard drive, and you can view them to see which Web sites that you visit are associated with your cookie files. If using Internet Explorer, for example you select Tools then choose Internet Options. On the general tab you will see a section titled Browser History.

This will open up a Windows Explorer window that lists all your temporary Internet files, including your cookies. Each cookie will be identified by a site URL making it easy to determine which cookies you trust and want to keep and which you don't recall from visiting a Web site and would delete.

To change your cookie settings, simply to go back into Tools then choose Internet Options. On the Privacy tab you will see a slider bar which you can move to adjust the level at which your browser accepts cookies. Low for example blocks third-party cookies that do not have a compact privacy policy and restricts third-party cookies that save information that can be used to contact you without your consent. Medium High will do the same but also block first-party cookies that save information about you. Other privacy options you can choose would be to accept all cookies or to block all cookies as well.

If you're using a browser other than Internet Explorer, you can visit the following cookie pages on each browser Web site to find out how to manage your cookies when using Firefox, Opera, or Safari.

Ø Firefox: Firefox Help: Firefox's Cookie Options

Ø Opera: Security, Privacy and Cookies in Opera

Ø Safari: Safari Help Managing cookies

Backup

Backup

In computing the phrase backup means to copy files to a second medium (a disk or tape) as a precaution in case the first medium fails. Planning your backup strategy is identifying what needs to be backed up. Identify the files and folders that you cannot afford to lose. It involves your documents, databases, pictures, videos, music and program setup or installation files. Some of these media like pictures and videos may be irreplaceable. Others like documents and databases may be tedious or costly to recover from hard copies. These are the files and folders that need to be in your backup plan.

Backups have two distinct purposes.

·        The primary purpose is to recover data after its loss, be it by data deletion or corruption. Data loss can be a common experience of computer users.

·        The secondary purpose of backups is to recover data from an earlier time, according to a user-defined data retention policy, typically configured within a backup application for how long copies of data are required.

Backup Strategy or Backup Policy

A backup strategy or backup policy is essentially a set of procedures that you prepare and implement to protect your important digital content from hard drive failures, virus attacks and other events or disasters.

Features of a Good Backup Strategy

The following are features to aim for when designing your backup strategy :

• Able to recover from data loss in all circumstances like hard drive failure, virus attacks, theft, accidental deletes or data entry errors, sabotage, fire, flood, earth quakes and other natural disasters.
• Able to recover to an earlier state if necessary like due to data entry errors or accidental deletes.
• Able to recover as quickly as possible with minimum effort, cost and data loss.
• Require minimum ongoing human interaction and maintenance after the initial setup. Hence able to run automated or semi-automated.

Backup Types

Many backup software offer several backup types like Full Backup, Incremental Backup and Differential backup, etc. Each backup type has its own advantages and disadvantages. Full backups are useful for projects, databases or small websites where many different files (text, pictures, videos etc) are needed to make up the entire project and you may want to keep different versions of the project.

1. Full Backup

Full backup is a method of backup where all the files and folders selected for the backup will be backed up.  It is commonly used as an initial or first backup followed with subsequent incremental or differential backups. After several incremental or differential backups, it is common to start over with a fresh full backup again.

Some also like to do full backups for all backup runs typically for smaller folders or projects that do not occupy too much storage space.

Advantages

• Restores are fast and easy to manage as the entire list of files and folders are in one backup set.
• Easy to maintain and restore different versions.

Disadvantages

• Backups can take very long as each file is backed up again every time the full backup is run.
• Consumes the most storage space compared to incremental and differential backups. The exact same files are be stored repeatedly resulting in inefficient use of storage.

2. Incremental backup

Incremental backup is a backup of all changes made since the last backup. The last backup can be a full backup or simply the last incremental backup. With incremental backups, one full backup is done first and subsequent backup runs are just the changed files and new files added since the last backup.

Advantages

• Much faster backups
• Efficient use of storage space as files are not duplicated. Much less storage space used compared to running full backups and even differential backups.

Disadvantages

• Restores are slower than with a full backup and differential backups.
• Restores are a little more complicated. All backup sets (first full backup and all incremental backups) are needed to perform a restore.

3. Differential backup

Differential backups fall in the middle between full backups and incremental backup. A differential backup is a backup of all changes made since the last full backup. With differential backups, one full backup is done first and subsequent backup runs are the changes made since the last full backup. The result is a much faster backup then a full backup for each backup run. Storage space used is less than a full backup but more then with Incremental backups. Restores are slower than with a full backup but usually faster then with Incremental backups.

Advantages

• Much faster backups then full backups.
• More efficient use of storage space then full backups since only files changed since the last full backup will be copied on each differential backup run.
• Faster restores than incremental backups.

Disadvantages

• Backups are slower then incremental backups.
• Not as efficient use of storage space as compared to incremental backups. All files added or edited after the initial full backup will be duplicated again with each subsequent differential backup.
• Restores are slower than with full backups.
• Restores are a little more complicated then full backups but simpler than incremental backups. Only the full backup set and the last differential backup are needed to perform a restore.

Incremental vs Differential vs Full Backup

Side by side comparison

	Incremental Backup	Differential Backup	Full Backup
What is it	A backup of all changed and new files since the last backup	A backup of all changed and new files since the last full backup	A backup of all files in a specified backup set or job
Backup Speed	Fastest	Faster	Slowest
Restore Speed	Slowest	Faster	Fastest
Storage Needed	Least	More	Most
Advantages	Faster backups Less storage space used. No duplicate files	Faster & simpler restores then incremental backup Only needs the first full backup and last differential backup to restore	Fastest restore Only needs the last full backup set to restore
Disadvantages	Slowest restores Needs all backup sets full + all increments to restores	Slower backups Still stores a lot of duplicate files	Needs the most storage space Inefficient storage with a lots of duplicates stored

4. Local Backup

A local backup is any backup where the storage medium is kept close at hand. Typically, the storage medium is plugged in directly to the source computer being backed up or is connected through a local area network to the source being backed up.

Examples of Local Backups

• Internal hard drive
• External hard drive (desktop or portable)
• Optical drives like CDs, DVDs and Blue Ray discs
• Solid state drives like USB Thumb drives or Flash Drives
• Network Attached Storage (NAS)
• Backup to a shared folder on another computer over the network
• Magnetic tape drives

Advantages

• Offers good protection from hard drive failures, virus attacks, accidental deletes and deliberate employee sabotage on the source data.
• Very fast backup and very fast restore.
• Storage cost can be very cheap when the right storage medium is used like external hard drives
• Data transfer cost to the storage medium can be negligible or very cheap

• Since the backups are stored close by, they are very conveniently obtained whenever needed for backups and restore.
• Full internal control over the backup storage media and the security of the data on it. There is no need to entrust the storage media to third parties.

Disadvantages

Since the backup is stored close by to the source, it does not offer good protections against theft, fire, flood, earthquakes and other natural disasters. When the source is damaged by any of these circumstances, there’s a good chance the backup will be also damaged.

5. Offsite Backup

Offsite Backup

Any backup where the backup storage medium is kept at a different geographic location from the source is known as an offsite backup. The backup may be done locally at first on the usual storage devices but once the storage medium is brought to another location, it becomes an offsite backup.

Examples Of Offsite Backups

• When the backup drives of the office computers are taken home by the Administrator or Manager for safekeeping.
• When the backup drive is kept at another branch office at another site or building.
•  When the backup drive is kept at a bank safe deposit box.
• When the backup is sent across the Internet or network connection to a storage facility or data centre in another city. (Also known as online backup or remote backup)

Offsite backups offer all of the same protection as local backups with added protection against theft, fire, floods, earthquakes, hurricanes and other natural disasters. Putting the backup media in the next room as the source would not be considered an offsite backup as the backup does not offer this added protection.

Advantages

• Offers additional protection when compared to local backup such as protection from theft, fire, flood, earthquakes, hurricanes and more.

Disadvantages

• Except for online backups, it requires more due diligence to bring the storage media to the offsite location.
• May cost more as people usually need to rotate between several storage devices. For example when keeping in a bank deposit box, people usually use 2 or 3 hard drives and rotate between them. So at least one drive will be in storage at any time while the other is removed to perform the backup.
• Because of increased handling of the storage devices, the risk of damaging delicate hard disk is higher. (does not apply to online storage)

6. Online Backup

An online backup is a backup done on an ongoing basis to a storage medium that is always connected to the source being backed up. The term “online” refers to the storage device or facility being always connected. Typically the storage medium or facility is located offsite and connected to the backup source by a network or Internet connection.  It does not involve human intervention to plug in drives and storage media for backups to run.

Many commercial data centers now offer this as a subscription service to consumers. The storage data centers are located away from the source being backed up and the data is sent from the source to the storage center securely over the Internet.

Typically a client application is installed on the source computer being backed up.  Users can define what folders and files they want to backup and at one times of the day they want the backups to run. The data may be compressed and encrypted before being sent over the Internet to the storage data center.

The storage facility is a commercial data center located away from the source computers being backed up. Typically they are built to certain fire and earthquake safety specifications.  They have higher security standards with CCTV and round the clock monitoring.  They typically have backup generators to deal with grid power outages and the facility is temperature controlled. Data is not just stored in one physical media but replicated across several devices. These facilities are usually serviced by multiple redundant Internet connection so there is no single point of failure to bring the service down.

Examples of Online Backups

There are many commercial service providers offering this as a subscription service. Some market it under the term Remote Backup or Cloud Backup.

Advantages

• Offers the best protection against fires, theft and natural disasters.
• Because data is replicated across several storage media, the risk of data loss from hardware failure is very low.
• Because backups are frequent or continuous, data loss is very minimal compared to other backups that are run less frequently.
• Because it is online, it requires little human or manual interaction after it is setup.

Disadvantages

• Is a more expensive option then local backups.
• Initial or first backups can be a slow process spanning a few days or weeks depending on Internet connection speed and the amount of data backed up.
• Can be slow to restore.

7. Mirror Backup

Mirror backups are as the name suggests a mirror of the source being backed up. With mirror backups, when a file in the source is deleted, that file is eventually also deleted in the mirror backup. Because of this, mirror backups should be used with caution as a file that is deleted by accident, sabotage or through a virus may also cause that same file in mirror to be deleted as well. Some do not consider a mirror to be a backup.

Many online backup services offer a mirror backup with a 30 day delete. This means that when you delete a file on your source, that file is kept on the storage server for at least 30 days before it is eventually deleted.  This helps strike a balance offering a level of safety while not allowing the backups to keep growing since online storage can be relatively expensive.
Many backup software utilities do provide support for mirror backups.

Advantages

           ·        The backup is clean and does not contain old and obsolete files.

Disadvantages

          ·       There is a chance that files in the source deleted accidentally, by sabotage          or through a virus may also be deleted from the backup mirror.

     

8. Remote Backup

Remote backups are a form of offsite backup with a difference being that you can access, restore or administer the backups while located at your source location or other physical location. The term “remote” refers to the ability to control or administer the backups from another location.
You do not need to be physically present at the backup storage facility to access the backups.
Putting your backup hard drive at your bank safe deposit box would not be considered a remote backup. You cannot administer or access it without making a trip to the bank. The term “remote backup” is often used loosely and interchangeably with “online backup” and “cloud backup”.

Examples of Remote Backup

• Subscription backup services provided by commercial data centers.
• Backup to an offsite FTP Server.

Advantages

• Much better protection from natural disasters than local backups.
• Easier administration as it does not need a physical trip to the offsite backup location.

Disadvantages

• More expensive then local backups.
• Can take longer to backup and restore than local backups.

Cloud Backup

Cloud backup is a term often used loosely and interchangeably with Online Backup and Remote Backup.  This is a type of backup where data is backed up to a storage server or facility connected to the source via the Internet. With the proper login credentials, that backup can then be accessed securely from any other computer with an Internet connection. The term “cloud” refers to the backup storage facility being accessible from the Internet.

Examples of Cloud Backup

• Subscription backup services provided by commercial data centers.
• Backup to an offsite FTP Server over the Internet.

Advantages

• Since this is an offsite backup, it offers protection from fire, floods, earth quakes and other natural disasters.
• Able to easily connect and access the backup with just an Internet connection.
• Data is replicated across several storage devices and usually serviced by multiple internet connections so the system is not at the mercy of a single point of failure.
• When the service is provided by a good commercial data center, service is managed and protection is un-paralleled.

Disadvantages

• More expensive then local backups.
• Can take longer to backup and restore.

9. FTP Backup

This is a kind of backup where the backup is done via the File Transfer Protocol (FTP) over the Internet to an FTP Server. Typically the FTP Server is located in a commercial data center away from the source data being backed up. When the FTP server is located at a different location, this is another form of offsite backup.

Examples of FTP Backup

Some commercial web hosting providers also provide an FTP server when you sign up for a web hosting service. Some providers do allow you to use this for backups but note that not all of these service providers allow you to use the FTP server to backup your local computer files. Some of these service providers have been known to even delete these backups without warning. Hence you must verify with your service provider before you start to do FTP backups on these servers.

Once you have organized an FTP server that you can use, you need to install a backup software utility that supports an FTP backup. You would need to specify the web address of your FTP server (like ftp://your-ftp-server/) , your login username and password so the backup utility can execute the backup.

Advantages

• Since this is an offsite backup, it offers protection from fire, floods, earth quakes and other natural disasters.
• Able to easily connect and access the backup with just an Internet connection.

Disadvantages

• More expensive then local backups.
• Can take longer to backup and restore. Backup ane restore times are dependant to the Internet connection.