Backup to disk is a method commonly used by small businesses to protect their data. However, there is not one form of best practice that suits all instances. The use of disk rather than tape is generally a matter of choice and can be determined by many issues including, cost, speed of backup / restore, the amount of data , etc.

However, small businesses should think about how their business may grow and what their requirements may be in the future. Although backup is always top priority, archiving or longer term retention of data should also be high on the list of items to consider.

An easy option?

For many small businesses, the easy option is to choose to save data to an external hard disk connected via USB or FireWire. Although this method works, it does provide limited protection and the backup process is generally performed as a manual procedure and offers little opportunity for automation or system restore. If saving data to disk is the preferred method of protection, additional or alternative disk space can be added easily to a system as data increases. This may be as simple as adding further external drives or something more meaty such as a RAID.

Where automation and improved backup efficiency is a necessity, software is generally required to manage these data protection processes.

The choice of software

Once a business has made an initial analysis of its data protection and software needs, it can then look for a backup software solution to meet those needs.

Flexibility is key

Many small businesses may well choose "backup-to-disk" as the easiest form of backup to protect data, but when software is needed, prudent consideration must be given to the growth of their business. Thought should be given to the growth of data; whether data should be held off site; will additional backup media be required; will any data be archived? Basically review and consider alternative strategies to protect valued your company's valued data. As businesses grow, data can also grow at an alarming rate. Therefore the software selected must be scalable, be able to manage the increase in data, handle operating systems on which data is stored, handle potential cross platform issues and also be capable of utilising other storage media such as tape.

The two common forms of backup to disk

The first is involves the simple duplication of data from one disk to another - "disk to disk" backup or "data replication". This is like taking a snapshot of the data at a given point in time and saving it to another location.

In general, this form of backup is adopted by a smaller businesses that needs to ensure short term retention of data, whereby data is replicated on a daily basis so if data is lost from one day to the next, it can be restored quickly. This process can also be used to manage longer term retention of data by copying data to disk on an "as and when needed" basis. This is what most call "data archiving".

The second is the adoption of "virtual tape" library technology or hard disk based backup systems. A virtual tape library is similar to a normal tape library or autoloader but data is backed up to disk. Software is utilised to manage how the storage on the disk is used to protect data to also to manage the data backup plans. These types of systems sometimes offer both Backup and Archive functionality.

Although many virtual tape libraries (VTLs) operate in a similar way to a normal tape library, it is worth taking the time to check that the basic requirements for backup are catered for. Most professional software solutions that manage backup to tape, require that at least two backup cycles are maintained; one cycle (full backup and incrementals) is retained and the other used for the current cycle. This ensures there is always one full cycle (full backup plus incrementals) available for restore. VTLs often have a similar requirement. Therefore anyone thinking about using a VTL as a means to manage backup and/or archiving, should check how much disk storage space is required for the backup and archive data. In general when using VTL, users will require over twice the amount of disk storage space for the data they need to backup plus additional storage for archiving.

For more information about this topic, also see Archiware PresSTORE's "Backup to disk, best practice for small business" knowledge base article offers some suggestions and alternative strategies for small businesses that are considering disk as a medium to backup or archive their data.