Data Backup and Recovery

The first step in planning your backup strategy is to decide which business data is more important to your company. A possible categorization of the value of data in your organization can be as follows.

Extremely important: Data without which your business cannot function. This would include stuff such as pending orders, unpaid bills, proposals under negotiation and salary information.

Moderately important: Data that is critical, but can be rebuilt with time and from other sources as well. This would include other accounting data and HR information.

Less Important: This would be departmental data.

Unimportant: Personal data of users (pictures, mail, music) is unimportant from an organization’s point of view.

Now you can back up the more important files and leave out the lesser important ones.

Where to backup from?



There are three different scenarios for backup in an organization:

Personal backup in a workgroup: This is a typical environment for 5-20 users, where there is no central file server. In this case backup has to be done on each machine using a common shared device or even individual backup devices. You can even use a CD-writer for this purpose, though given today’s larger hard disks, you would have to use quite a large number of CDs if you want to back up full hard disks every time.

Server Backup in a client-server network: If you use one or more servers, then you could have a system where along with your centralized applications such as accounting/ERP packages and databases, you could encourage users to keep their data on servers, and then these servers could be backed up.

Server and client backup in a large network: Today, it is normal for desktop systems to have 20-40 GB HDD. A lot of critical data resides on these hard disks. Also, as the number of servers increase, it becomes difficult and uneconomical to back up each of these separately. At this stage you will have to go in for network wide, software-based backup solution that includes separate backup servers and can back up specified data from both the desktops and the servers.

Whichever of the above you decide to choose, the machines to be backed up, as well as the applications, the files and the folders have to be identified first.

Timing



Backup is a resource hungry process, taxing systems and networks heavily. Typically you do not do a backup when the network is being used for regular work, because the data flow over the network for backup will slow down the regular work significantly. The usual option for doing back up is to choose a time when the rest of the office is not working. Everyone wants to back up in the least time, but faster backup media and drives cost more than slower solutions. Therefore, full backups should be done on weekends when there is no user load and the backup window is about 24-36 hrs. Incremental backups can be done on weekdays, after office hours with a backup window of 3-12 hrs.

Full, incremental? Now what is that? You do not backup all the data every day. You do that once in a while and in between you backup the changes you have made or the additional data you have added. Now, how do you determine that? This is done by the backup software.

Physical protection of the backup media



Once you have backed up your data, it is important to take care of your backup media. It should be kept in a safe place to avoid damage. Also the media should be properly marked and easily accessible to the backup operator. For the extremely important data it is a good idea to store at least one copy of the backup at a remote location (could be your own house or a branch office).

Different Backup options



Flash memory:

Especially the USB key memory is ideal for fast personal backup and data sharing. They are more durable than floppy and optical disks but are more expensive too.

Optical disks: Optical disks are a cheap and reliable medium for making personal backups on individual systems as well as for sharing files among users. But the maximum limit is only 700 MB with CD-R/RW disks. DVD-R/RW disks increase this limit to 4.7 GB but they are expensive both in terms of media and drive. 

Tape drives: Tapes have always been the most popular backup option, ranging from the single file server backups to the network wide backups. Tapes provide high durability, high archival and operational life. There are several tape formats available in the market. Price, speed and capacity vary widely. As the amount of data to be backed up increases, you do not necessarily increase the capacity of a single tape, but add more tapes. 

It is a fairly tedious process to back up tape after tape, and keep proper track of them too. So, it is better to use autoloaders.

They take in a bank of tapes and manage the backup (and recovery process) across this bank.

Disks: With the decrease in disk costs, disk-based backup is fast becoming a viable option for making large volume backups that can replace the tape entirely. They are fast and easy to restore.