A common concern with using an online backup provider to backup large amounts of data is the time required to transmit the data to the offsite storage facility. If you have ever tried to copy volumes of data over a T1 or Internet connection you know what I am talking about. This is one reason that some people believe that online backup services are primarily used for small amounts of data. Newer technological advances are making it practical to backup substantial amounts of data to online backup facilities.
The simplest of these technologies has been around for many years. Incremental backup methods only copy files that are new or have been updated since the last backup. Traditional media backup schemes typically require periodic full backups, in addition to incremental backups on a more frequent schedule. The periodic full backup is needed for two reasons; 1) the full backup along with all subsequent incremental backups were needed to restore all files in the backup set to their most current state, and 2) the periodic full backup is needed so that the incremental backup media consumed between full backups can be returned to the scratch pool. Online backup services do not require periodic full backups. Online backup services can assemble the most current backups of a set of files without the need to locate and mount media. A entire set of files can be restored at anytime as if a full backup were made as of the last time an incremental backup was run. Online backup services typically store files using online or near-line storage that make media scratch pools obsolete. With online backup services, only new files and modified files are actually transmitted to the offsite storage facility. Online backups typically transmit only a fraction of the amount of data required by a full backup, and yet maintain current backup copies of all files.
Advances in data compression have also contributed to the efficiency of online backups. Online service providers typically use the latest data compression techniques to reduce the bandwidth required to backup files. It is not unusual to see text files, spreadsheets, databases and other documents compressed to 15 - 20% of their original size. Executable files can usually be compressed to about 50% of their original sizes.
The more advanced online backup services utilize delta file technology to backup only the parts of large files that have changed. When a large file is changed, the delta file technology can determine which parts of the file have changed and which parts have not changed. The online backup system can then transmit only the changed parts of the file to the offline storage facility and combine those parts with the sections of the file that were previously backed up and remain current. Your first impression may be that the files may get corrupted since they are being backed-up in pieces. The technology is actually quite solid and the backup files are usually validated with various hashing and checksums to ensure that the file in the backup storage facility that was backed-up in pieces remains identical to the file on the computer that is being backed up.
The combination of incremental backup, data compression, and delta file technology make it practical for home users and businesses to backup significant amounts of data in an expedient manner. Online backup services offer several advantages over traditional backup systems and should be seriously considered. All online backup services are not equipped to handle large volumes of data. If your data backup requirements include large amounts of data, then research online backup providers who provide all three technologies; incremental, data compression and delta file technology.
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