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.