The maximum disk space that is used on a query server or on an index server increases to 2.85 times the physical size of the index after you install Office Servers Service Pack 1

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 index.

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.