Start/notes.ini Parameters/NSF_Buffer_Pool_Size_MB

NSF_Buffer_Pool_Size_MB

Parameter: NSF_Buffer_Pool_Size_MB
Short description: Sets the maximum size of the NSF buffer pool (database cache of the NSF engine) in megabytes.

Profile

Parameter
NSF_Buffer_Pool_Size_MB
Category
Performance / Memory
Component
Server
Available since
9.0.1
Supported versions
9.0.1, 10.0, 11.0, 12.0, 14.0, 14.5, 14.5.1
GUI equivalent
notes.ini only (no GUI)
Possible values
Integer in MB; 0 = automatically calculated; typically 512 – 4096 MB

Description

The NSF buffer pool is the central cache in which the NSF engine holds database pages (NSF Pages) in main memory. With NSF_Buffer_Pool_Size_MB, the maximum size of this pool is set firmly in megabytes and overrides the default calculated by the server itself.
A correctly sized buffer pool significantly reduces physical read accesses to the database files and is an important performance lever, particularly on mail and application servers with a high number of databases. Values that are too small lead to high disk I/O and a poor cache hit rate; values that are too large can crowd out other subsystems (e.g. full-text indexing, view indexing) or lead to memory pressure on 64-bit servers with limited RAM.
On 64-bit Domino, the value effectively determines how much addressable heap is available to the NSF cache. The server takes the value into account at startup; changes only take effect after restart.

Example configuration

NSF_Buffer_Pool_Size_MB=2048

Notes & pitfalls

  • Only takes effect after server restart, not via set config.
  • Value should match the available RAM and the server's working set – rule of thumb: NSF buffer pool together with view and FT indexer memory must not exceed the available physical RAM.
  • Monitor effects via show stat Database.Database.BufferPool.* or show stat Database.Database.BufferPool.PerCentReadsInBuffer.
  • On servers with DAOS or many small NSFs, a larger pool has a particularly strong effect.
  • The deprecated variant NSF_Buffer_Pool_Size (in bytes) should no longer be used – use only the _MB variant instead.

Sources (HCL Product Documentation)