After you install Microsoft Office Servers Service Pack 1 (SP1), the maximum disk space that is required on
a query server or on an index server increases. The maximum disk space
requirement is now 2.85 times the physical size of the index. Previously, the
maximum disk space requirement was 2.5 times the physical size of the
This issue occurs because Microsoft has changed the method
that is used to merge indexes in Office Servers SP1. This change
significantly improves performance, and it reduces server downtime. However, this
change also increases the disk space requirement.