Data reduction
IASOs backup solutions leverage the fact that on a daily basis, only a minor proportion of an organisations data set is changed. Once produced, most data files remain relatively static. In principle it is not necessary to include more than the minimal changes and additions to the data set in the daily backup, provided of course that vice versa the backup solution has the necessary intelligence to put the data back together transparantly, when a restore is required.
Advanced Technology
In order to reduce the disk space required to store backup data, IASO uses an advanced data reduction mechanism. This technology is extremely efficient: on average less than 0,5% of the original dataset changes during the course of a day, and that 0,5% is what needs to be stored. IASO combines this advanced technology with a technique we call journalling , which basically means that from each backup session, the contents are recorded as a set of pointers to the actual data blocks.
If a data block is already present on the backup server, as part of the first full backup or from one of the previous backup sessions, no actual data needs to be transmitted. When a restore needs to be performed, the software addresses the journal of the backup session from which data is required, and the full dataset is available, as the journal contains pointers to all datablocks, no matter from which backup session they originate.
The net result of the IASO solution is that the backup server can contain as much as 50 - 100 full backups on the same disk volume as the original data set. A simple calculation supports this claim:
Suppose a 100 GB dataset needs to be backed up daily; the first time obviously all data needs to be stored on disk, as no data blocks are present yet. Using standard data compression, the data set is reduced to about 60 GB on average. The following days roughly 0,5%- 1,0% of the data blocks are changed or new. The IASO software identifies these blocks, compresses and stores them, requiring about 0,5% of 100 GB = 500 MB per day. After about 80 days a total of 100 GB data is actually stored on the backup server.
Obviously the technique not only reduces the amount of disk space required for backup, but also enables the data to be transferred to the backup server over a relatively slow IP connection, such as DSL.