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How to Setup Automated Off-Site Backups to
your On-line File Storage

I'll re-iterate our warning, given elsewhere on this website, that over even the best Broadband Internet connection, you should aim to upload no more than 500mb per day.
The following diagram shows who else you are competing with for Internet bandwidth on a typical business-grade Broadband connection when you're performing an off-site backup:-

Diagram showing bandwidth limitations for Off-site backups  

Even uploading 500mb per day adds up to 15gb per month, which your ISP may object to.
Any backup should also be done out of hours so as not to slow down the rest of your office's Internet access during the working day.

The good news is that you've got to be a pretty big office to be generating more than 500mb of new and changed data each day.
The big lesson here is that you must use this upload bandwidth in a smart way, by only uploading the changes to your data and not blindly upload a full copy of all your data each day.

Even smarter is to use one of the various "block level" synchronization programs such as the updated DFS program that comes with Windows Server 2003 Release 2.

Block Level programs only copy those parts of a file that have changed and so lessen the amount of data required to be transmitted to keep large files synchronised with their off-site copies.

Exchange is optimised for email and not for off-site synchronization, so once a day it runs an on-line defragmentation of its database where chunks of data are moved around, within the database file, to make access more efficient.
This means that, after a defragmentation, a large percentage of the file will have changed so that even a block level synchronization program will have to send more data than there are real changes to the database.

Therefore, this defragmentation process works to largely defeat the advantages of a block level synchronization program.

Arrowmail on-line storage doesn't currently support block-level synchronization programs.


Companies that need to send large amounts of data off-site, such as banks, still need to use expensive point-to-point leased data circuits between locations so they can have full uncontended, unmetered use of the circuit's bandwidth.


To perform your off-site backup to on-line file storage, such as offered by Arrowmail, means you will need to use a synchronization program which will propagate changes made to your locally stored files to your online storage.
These changes are new files, modified files, files moved to new locations and deleted files.

While this form of backup means you will have an up-to-date copy of all of your files in a safe off-site location in case some disaster strikes your office, it doesn't achieve all the goals that may be required of a backup system.

If you delete or make an error modifying a file which you don't discover for a few days, there won't be multiple point-in-time backups going back a week or more from which the desired version of the file can be recovered.
A daily full backup to tape, where individual tapes are recycled weekly or monthly, would achieve this backup goal.

You can also access Arrowmail's on-line storage using FTP which allows FTP-based synchronization programs to be used, such as FTP Voyager from Rhinosoft.
There are many other synchronization programs that will work with Arrowmail's online storage using mapped drives or FTP.

There are some files that are just not suited to this type of backup.
The best example is the database files that Microsoft Exchange uses to store a companies email data.
Even with the standard version of Exchange, these files can grow to 75gb and, even in a small office, these files are likely to be over 4gb.
While, over the course of a day, the majority of the data in the email database won't change, the arrival of just one new email will mean the whole multi-gigabyte file will be out-of-date and need copying in it's entirety to off-site backup.

The Holy Grail of having a complete off-site backup of all your company data where it's safe from any disaster imaginable, it all works automatically and you never need to change any backup tapes is not achievable today without throwing a lot of money at the problem.
By accepting the current Internet bandwidth limitations and working in a smart way, the most important sub-set of your company data, perhaps up to 2gb, can be backed up off-site.


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