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Online Backup

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++ Online Backup TECHNOLOGY

Online Backup (also called ‘Backup Online’, ‘Backup via the Internet’, ‘Offsite Backup’ or ‘remote backup’) is a system which copies data from a PC or server via the Internet to a backup server located elsewhere through a software program (backup client). If data are lost from your PC or server, they can be returned (restored) online from this backup server to your PC.

Making a backup
The computer from which your backup has to be made is equipped with client software. This client software links you to the backup server, which is located at a data centre. You (or Verlee Consultancy if you buy this service managed) can set a number of options in the client software, such as:

  • which files should be copied;
  • when the backup should be performed (usually in the evening or night, when your Internet connection is not being used for other purposes, and when most of the files are not opened);
  • for how many days you want your files to be stored on the backup server after having deleted them from your computer or altered them;
  • which key should be used for encrypting the data before transferring them on the Internet;
  • which type of encryption you wish to use (standard type is AES);
  • to which e-mail addresses the status reports should be sent;
  • whether you wish to have another copy of the backup files on your own computer.

When you have installed and set everything, the backup client tries to copy as many files as possible to the backup server from the preset start time to the preset end time, or until all files have been copied. The first time there is often not enough time to copy all files.

An example:
Let’s say you have an ADSL Internet connection which can upload (send to the Internet) 512 Kbps (Kilobits per second). This is about 200 MB (Megabytes) per hour. Your data have been compressed, so the volume of the files on your PC may be considerably larger. If you set the backup client to run between 21.00 pm and 07.00 am, in this example it can copy 2 GB (Gigabytes) to the backup server. But encrypting and comprising the files takes some time, so in practice, the transfer rate will be about 1 to 1.3 GB.

If the backup procedure is not completed in one go, next time the client program will continue where it left off. This will be repeated until a full backup has been made. During the subsequent backup sessions only the altered files will be stored. For small and medium-sized companies this can usually be done within one hour. When a full backup has been performed, a report is sent to the preset e-mail address, mentioning:

  • which new files have been copied;
  • which altered files have been copied;
  • which files could not be copied because they were being used;
  • what the total volume is of your data on the backup server.

If you set everything correctly, you will receive a daily e-mail informing you that a successful backup has been made.

Restoring files
If data are lost from your PC you can restore them with the backup client. First you need to put some information in the program, such as:

  • which files should be restored;
  • of which date you need these files (standard procedure is the most recent date) *;
  • whether the files should be restored to their original location or to another location.

When you have set these options, you can restore your files. You can also restore your files on another PC. Not with the client program, but you can do it via the website backup.verlee.nl (only for clients of Verlee Consultancy). This may be helpful when you are not in your office and you urgently need a file.

* Before you started making backups, you set the period for storing your files on the backup server. The standard setting is 90 days. This means that if you change a file every day, there will be 90 versions on the backup server.

All files are encrypted before they are transferred on the Internet. The encryption is performed with the AES protocol. As a standard procedure, the key is the same as the client’s password for the backup server. This password is also known to Verlee Consultancy. You can alter the key, however. If you alter it, the client program will ask for this key when you wish to restore files. Please note: if you lose this key, all data on the backup server will be illegible and hence useless! No one, not even Verlee Consultancy or the American authorities can recover your original data.

In order to limit the amount of data to be transmitted via the Internet, the backup software compresses all files, or at least tries to do so. Some files, like text documents or databases can easily be compressed. For other data, however, like music files and images, it is not so easy. Below you will find an overview of various types of files with their compression ratio. A ratio of 0% means that the file cannot be compressed and that it will be transmitted full-size. A ratio of 80% means that only 20% of the real volume of the file has to be transferred.

The values in the schedule are based upon files from Verlee Consultancy’s clients.

Type of file

Compression ratio in %

Microsoft Word document (.doc)


Microsoft Excel document (.xls)


Microsoft Access database (.dbf)


Microsoft Exchange database (priv.edb)


Microsoft Exchange transactielog (.log)


Microsoft SQL database


MS Windows 2003 systemstate (.bkf)


Adobe Acrobat file (.pdf)


Text files like log files (.txt)


Bitmap files (.bmp)

40 tot 80

Dynamic Link Libraries (.dll)

50 on average

Program files (.exe)

55 on average

Film files (.mpg)


Sound files(.wav)


Images (.jpg)


Music files (.mp3)


Making backups of databases
The client program has a number of options for making backups of databases. It can handle the following databases:

  • Microsoft Exchange
  • Microsoft SQL
  • MySQL
  • Oracle
  • Lotus Domino / Notes

Online Backup at Verlee Consultancy
Verlee Consultancy has a primary backup server with double power supply. We use RAID6 including hot spare. This means that if two disks fails this has no consequences for the data, nor for the functioning of the server. If a disk fails, the hot spare disk is automatically put into action. It will take over the function of the faulty disk in a couple of hours. The backup server is located at a secure data centre in Amsterdam. It is connected to the Internet via a Cisco firewall. In case that three disks fail within a couple of hours, the primary backup server is backed up by a second server. This server is equal to the first one, but residing at another location.

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