It is clear that data backup and recovery is a complex discipline, and one that poses a great deal of risk for your company and your electronic data. But it can be overcome through thoughtful planning and preparation.
Types of Backups
As time goes by, any successful business will grow and with the expansion, complexities will increase as well in the form of multiple and often overlapping processes across multiple simulations executing platforms. This has a direct impact on the complexity of data backup as the two are directly proportional. So, what are the nuts and bolts?
Things to consider
- What types of backups does your backup application support?
- What does your service-level agreement dictate in regard to recovery time?
- What are the policies regarding storing backup tapes offsite?
- Are there regulatory requirements in terms of backup and data retention
There are far too many examples on the Internet of companies going out of business due to data loss and their inability to recover from a data loss event. All of these could have been prevented by backing up the data. Once you have decided on a strategy, you have to ask yourself if you know and understand how your data should be backed up. Typically, there are three ways.
For quite some time, there have been three basic types of backups: full, incremental and differential. More recently though, data backup software vendors have introduced some newer types of backups that you might not be familiar with. Some of these newer types are Mirror Backup, Full PC Backup or Full Computer Backup, Local Backup, Offsite Backup, Online Backup, Remote Backup, Cloud backup and FTP Backup. For the sake of this article, you basically need to be familiar with the main 3. I am going to give you a brief introduction to them.
Full Backup
All of the files and folders—everything that needs to be backed up—will be backed up in their entirety. It is exactly what the name implies. It is a full copy of your entire data set. Every time you back up your data (and in any subsequent backup operations), the files and folders will be backed up again entirely.
Normally, full backups are performed as initial backups, followed by either incremental or differential backups. This is done because they are time consuming, and often require a large number of tapes or disk Full backups are sometimes done periodically (example weekly, bi-weekly, or monthly) after several instances of incremental or differential backups.
Advantages
• Fast and easy recovery as complete data is readily available.
• Easy version control.
• Includes the full data set.
• Files and folders are backed up to one backup set.
Disadvantages
• More storage space is needed.
• Additional bandwidth required.
• Time-consuming if full backup is run all the time.
Incremental Backup
All of the files that have changed since the last backup was made, whether the backup was full or incremental, will be backed up. The main purpose of incremental backup is to shorten the time interval between backups, requiring less data to be backed up. For instance, if a full backup was made on Friday night, then an incremental backup may be performed on Monday night to back up files that have changed since Friday night. On Tuesday night, another incremental backup is performed to backup files that have changed since Monday night, and so on and so forth.
Advantages
• Fast backup windows, as there is less data as compared to full backups.
• Less storage space (disk, tape, or network drive) needed.
• Allow retention of several versions of same files.
Disadvantages
• Slower recovery, as all increments must be restored.
• Initial full backup is needed before incremental backups start
• A full backup and all incremental backups are needed for recovery.
• Takes longer to restore a specific file, as more than one backup set is needed.
• If one of the backups fails (either the full or incremental), then recovery will be incomplete.
Differential Backup
This backs up files that have been changed since the last full backup. For instance, if a full backup was performed on Friday night, then on Monday night, differential backup will back up all of the files that have changed since Friday night. On Tuesday night, differential backup will back up all files that changed on Monday and Tuesday. Then, on Wednesday night, it will back up all files that changed on Monday, Tuesday and Wednesday, and so on. In short, differential backups are cumulative incremental backups. The result is a much faster backup than a full backup for each backup run. Storage space used is much less than a full backup but more than with Incremental backups. Restores are slower than with a full backup but usually faster than with Incremental backups.
Advantages
• Less storage space (disk, tape, or network drive) needed as compared to incremental.
• Only full backup and the last differential backup needed for restore.
• Allow retention of several versions of same files.
Disadvantages
• Slower backups than incremental backups.
• Initial full backup is needed before differential backups start.
• A full backup and all differential backups are needed for recovery.
• If one of the backups fails, then recovery will be incomplete.
• Takes longer to restore a specific file, as you need to locate the file on backup sets.
The last and most practical of the steps would be the consideration of backup media to use for data storage. Alas, as with everything mentioned before, the decision relating to which technology to use for actual storage is not straight forward.
Types of Backup Medium
Find out which medium is going to be the best solution for your needs.
External Hard Drive
These are hard drives similar to the type that is installed within a desktop computer or laptop computer. The difference being that they can be plugged in to the computer or removed and kept separate from the main computer. They typically come in two sizes.
Description
Desktop External Hard drive: Uses a 3.5 inch hard drive similar to that used in desktop computers. Portable External Hard drive normally uses a 2.5 inch hard drive similar to that used in laptops. Desktop External Hard Drives are generally cheaper than Portable External Hard Drives for the same storage space. Desktop External Hard Drives usually faster and more robust.
Capacity : 160GB to 10TB (approx 10000GB)
Connection : Most common connections to the computer are through a USB 2.0 or USB3.0 connection. May also be available in a SATA or eSATA connector
Advantages
• Very good option for local backups of large amounts of data.
• The cheapest storage option in terms of Rand per GB.
• Very reliable when handled with care. Disadvantages
• Can be very delicate.
• May be damaged if dropped or through electrical surge.
Solid State Drive (SSD)
Solid State Drives look and function similar to traditional mechanical/ magnetic hard drives. That is where the similarities end. Internally, they are completely different. They have no moving parts or rotating platters and they rely solely on semiconductors and electronics for data storage, thus making it a more reliable and robust than traditional magnetic storage. No moving parts also means that they use less power than traditional hard drives and are much faster too.
Description
Capacity : 64GB to 10 TB
Connections : USB 2.0/3.0 and SATA
Advantages
• Faster read and write performance.
• More robust and reliable than traditional magnetic hard drives.
• Highly portable.
• Can be easily taken offsite.
• SSD has no moving parts, so it is more likely to keep data safe in case of accidental knock. Disadvantage
• SSDs are more expensive than hard drives in terms of Rand per gigabyte.
• Storage space is typically less than that of traditional magnetic hard drives.
• SSDs wear out over time (each cell in a flash memory bank can be written to and erased a limited number of times),
Network Attached Storage (NAS)
More often than not, it is a purpose-built specialized computer. A NAS unit is basically a computer connected to a network that provides only file-based data storage services to other devices on the network.
Advantages
• Very good option for local backups, especially for networks and small businesses.
• Several hard drives can be plugged in to hold very large amounts of data.
• Can be setup with Redundancy (RAID) increasing the reliability and/ or read and write performance. Depending on the type of RAID level used, the NAS can still function even if one hard drive in the RAID set fails. Or two hard drives can be setup to double the read and write speed of single hard drive.
• The drive is always connected and available to the network making the NAS a good option for implementing automated scheduled backups.
Disadvantages
• Significantly more expensive than using single External Hard Drives.
• Difficult to bring offsite making it very much a local backup hence still susceptible to some events like theft and floods, fire etc.
Optical Drive (CD/ DVD)
Optical storage is any storage method in which data is written and read with a laser for archival or backup purposes. Typically, data is written to optical media, such as CDs and DVDs. A number of new optical formats, such as Blu-ray and UDO (ultra density optical), use a blue laser to dramatically increase capacities
Description
Capacity CD : 650MB to 900MB
Capacity DVD : 4.7GB to 17.08GB
Capacity Blue Ray: Conventional (pre-BD-XL) Blu-ray Disc discs contain 25 GB per layer, dual layer discs (50 GB), triple-layer discs (100 GB) and quadruple layers (128 GB)
Capacity Ultra Density Optical disc/ UDO: 30 GB of data. The second generation UDO2 media has a capacity of up to 60 GBs.
Advantages
• Low cost per disk.
• Easily transportable.
• Optical media provide the capability to pinpoint a particular piece of data stored on it, independent of the other data on the volume. Disadvantages
• Relatively shorter life span than other storage options.
• Consumer based formats like CD-R and DVD-R, BD-R do not have a formal method of grading quality of discs.
• One damaged disk in a backup set can make the whole backup unusable.
• Optical storage is expensive per GB/TB in comparison to other technologies.
Cloud Storage
Cloud storage is normally service provider storage space in commercial data center, accessible from any computer with Internet access. Limited storage space may be provided free with more space available for a subscription fee. Examples of service providers are Amazon S3, Google Drive, Sky Drive etc.
Advantages
• Certain solutions can be accessed through specific desktop folders allowing users to drag and drop files between the cloud storage and their local storage.
• Managing of bandwidth by sharing web links instead of actual files.
• Stored files can be accessed from anywhere via Internet connection.
• Small storage costs per gigabyte compared to other options. Disadvantages
• An Internet connection is required to access data.
• Concerns with the safety and privacy of important data stored remotely due to the shared nature of cloud storage.
• If local manipulation of files is a requirement through multiple devices, the service must be downloaded on all devices.
Backups are a crucial component of any business. It is true that most data can be recreated in the event of loss, but it is going to take time and effort to do so, time and effort that could be better spent building the business. Much more can be said about backups, but at some point everything becomes an academic exercise and tend to become confusing. A territory frequented by consultants and vendors using fear-mongering, designed as a tool to make you depart from your hard-earned cash.
If you take into account the information shared in this article, and base your decision on your unique business environment, you are well on your way to creating a business saving solution customized to your requirements.
Find out more on the impact of this in your business in the other article on this topic, Data Backup: A recipe to Avert Disaster.
Author
Carel Krogh
This article was published with the permission of Carel Krogh
