Initial Backup:

All data selected for backup is compressed in a backup file.

A separate index file is also created detailing files and their hashes.

The maximum size of this backup file can be limited, in which case the Backup Client will compress until the limit is reached and then flag any further files for backup at the next schedule time. Thus on the first backup only the first gigabyte of data (for example) will be backed up.

The next time (which could be an hour or a day later) the first gigabyte will be patched and the next gigabyte will be added, and so on until all files have been backed up and only patches need to be sent.

This process can automatically be cycled in Server Edition to speed up the process.

Patching:

Subsequent backups use a proprietary patching process to reduce the size of the backup. This works as follows:

1.	Backup Client does a scan of the files and folders and filters selected for backup.
2.	Any new files are compressed and form the new backup file.
3.	Any deleted or removed files are added to a deletion list.
4.	Any modified files (we use the modification date and do not reset the archive flag) are first checked against the local cache to see if a previous version of that file is in the cache. If so then the files are compared on a binary level (and thus the process is file type independent) and any changes are stored in a file patch and added to the backup file. Thus the greater the modification date setting of the cache the greater the chances of a previous version of a file being present to allow for the patching process.

Backup Transfer:

An SSL connection is established to the NameServer (NS) which verifies the account and passes the IP address of the FileServer (FS) where that accounts' data is stored.

The connection is dropped and a new SSL connection is established to the FS.

The files are then sent to the FS where they are stored in a dedicated account directory.

File hashes are checked to ensure file integrity.

Files are stored using 448-bit Blowfish encryption in CBC mode.

Local SnapShot:

Should the initial backup be too large for the available bandwidth, a portable FS (or DR Box) is temporarily installed on the client LAN and the initial backup is done to this unit.

The DR Box is then physically transported to the remote FS to which the backup is uploaded.

Subsequent backups, being incremental and thus smaller in size, will revert to using the available bandwidth.

This process is known as a Local SnapShot.

The same logical process applies to recovering large amounts of data to the server.

Proxy settings can be specified during these processes.

Local Cache:

Once the FS has confirmed the successful transfer of the initial backup, the Backup Client drops the connection and creates a local cache.

This is a compressed folder containing copies of all files that are backed up that had been modified in the previous 14 (default setting) days.

The size of this folder is dependent on the type and size of the files concerned and also the modification date setting.

To reduce the size of the cache the date can be reduced to files changed in the last 7 days etc. or turned off altogether. This will impact on the patching process.