A lot of backup systems pay little regard to the management of very large unique files.

With Fortikup it is possible to carry out daily backups of very large files, since with the In-File Delta technology it is possible to carry out the backup of the only differences brought about to the file (Delta File), without the need of transferring it wholly, with notable advantages in terms of time and commitment of the Internet band.
There are two different operating modes (differential and incremental); both the modes take approximately the same disk space in the server.

Differential Delta Mode
This mode will facilitate the restore of your backup. The delta is generated through the comparison with the latest complete version of the backup file. With this system the "Delta File" is increased every day by using a higher quantity of the Internet band with regard to the other mode. For the file restore at a determined date, it will be necessary both the complete file and the "Delta File".

Incremental Delta Mode
The incremental mode will facilitate your backup performances. The delta is generated through the comparison either with the latest Full or Delta version of the backup. In this way the Delta File will be of very reduced dimensions and will use less Internet band during the backup operations.
For the restore, both the Full of the file and all the generated Delta ones will be necessary.

In-File Delta Technology	Pros	Cons
Differential	To carry out the restore at a specific date, it only needs the Full and Delta version of the file that is the subject of the backup.	The Delta File will increase its dimensions day by day, therefore it will need a larger Internet band to be transferred.
Incremental	The Delta File will daily contain the mere difference between the current file and the latest version saved. Therefore the Delta File will be smaller and will need a lower Internet band for its transfer.	To carry out the restore, it will be necessary to download the Full version plus all the Delta Files previously generated. Should a Delta File result to be corrupted, it will be possible to carry out the restore only until the date of the last clean version.

Delta File Generation
The Delta File is generated by extracting the differences between the latest file version and the version stored on the backup server. Both files are divided in individual blocks by using the same block size. Blocks are then compared to determine any difference. The differences will be extracted in the Delta File.



Block Size Settings
If you want, it is possible to change the size of the Block Size for the function of In-File Delta. The relationship between the Block Size and the generated Delta File is the following one:

• Small blocks: the generated Delta Files will be smaller but the time to process them will be longer.
• Large blocks: the generated Delta Files will be larger but the time to process them will be faster.

The applicable block sizes are: auto, 1k, 2k, 4k, 8k, 16k, 32k, 64k, 128k, 256k, 512k, 1Mb.

With the function "Auto", the following criterion will be used:

Initial dimension of the File:	Auto Block Size function
> 15 Gb	64k
> 8Gb <= 15Gb	32K
> 2Gb <= 8Gb	16k
> 500Mb <= 2Gb	8k
<= 500Mb	4k