HFS : VPN-based Backup

1. VPN-based Backup to the HFS

From August 2010 the HFS will offer a backup service designed to provide members of the University with secure data backup from outside the University.

Other HFS backup services are limited to the University Network and to the University's eduroam wireless network, in order to ensure that backups and restores are completed in a timely manner. This service provides backup and restore functionality worldwide, via the University VPN service. It is intended for users who will be travelling out of Oxford for an extended period of field work, or who wish to back up machines that are rarely or never directly connected to the university network.

To use this service, firstly install and run the OUCS VPN client; then register for an HFS VPN-based backup account in the normal way, via the OUCS TSM client registration page.

2. Service Limits

• The service is designed to support the backup and restore of critical University data for users whilst they are away from Oxford.
• It is for the backup of critical University data only and is not for the general backup of home computers.
• The configuration of the client software must be carefully considered and where possible a limited set of data should be backed up. We highly recommend excluding all files from backup except for one or more key folders as described in our section on how to exclude everything from backup except a specific directory/folder.
• The service offers only manual backups. The nature of the service precludes offering a scheduled backup service.
• Dual registrations - systems registered both for VPN backup and desktop backup - are not permitted. If you wish to have a TSM account moved from the desktop backup service to the VPN backup service, please contact hfs@ox.ac.uk; once it has been moved, you will need to follow our instructions for changing to the VPN-based backup service
• Normal desktop backup limits apply: 100GB upload / day and a maximum backup connection of 10 hours. In practice you are unlikely to hit the former limit - see the following section for reasons why.
• Normal data retention limits apply: i.e. we require that your backups are kept up to date and are no more that 90 days old. This is in line with our standard deletion policy. If you suspect that the nature of your location will prevent you from backing your data up within a 90-day period, then we strongly advise you to contact us asking for a temporary suspension of the deletion policy for your account. We will require your name, the HFS account name (aka Nodename) and the period of time requested for.

3. Backup/Restore Speed

The key issue when accessing the HFS from outside the University Network is the speed of the connection. Backups via ADSL Broadband connections are particularly slow as the upload speed of the connection is significantly slower than the download speed. For this reason, where you require a large amount of data to be backed-up (i.e. uploaded) we strongly recommend that the initial backup to the HFS is carried out over a wired connection to the Oxford Network. Thereafter you can use backup-over-VPN for the small incremental backups of files as they change over time.

The download speed (restore) is usually ten times greater than the upload speed (backup) and occasionally the difference can be larger.

Approximate times for VPN-based backup/restore are given below:

These figures include an approximation, in the case of backup, for starting the session with the HFS and scanning the disk for files to back up; or, in the case of a restore, for waiting for the HFS systems to load the required tape and locate the position of the data upon the tape.

4. Broadband Quotas

As part of the backup process the HFS servers send a list of files which have been previously backed up to the machine performing a backup. This list is then compared with the files found on the disk to determine which files have been changed, created or deleted. For machines with a large number of files this list can be very large. Repeated backups of systems with a large number of files via broadband may, counter-intuitively, cause problems by exceeding broadband download limits. For this reason we strongly recommend that all files except for one or two key directories are excluded from backup (see above), and that machines with lots of small files to back up, to take extra care if using the VPN backup service.

5. Problems