SafePages are transient. They serve as scratchpad to accumulate and edit SavaPage print jobs. After ProxyPrinting and PDF exporting is done the user will normally clear the scratchpad for a new session. Of course this does not hold for personal Letterheads. Take in consideration that SafePages (including Letterheads) from logically deleted users are removed. This all makes the calculation of required disk space a simple linear function of the number of active users times the average size of a user's SafePages home. Since an average 10-page print job takes about 1 MB to hold in store, making a reservation of 10 MB per user seems fair enough.