Start/notes.ini Parameters/NSF_Buffer_Pool_Size

NSF_Buffer_Pool_Size

Parameter: NSF_Buffer_Pool_Size
Short description: Maximum size (in bytes) of the NSF buffer pool — a memory area that buffers I/O transfers between Domino and disk.

Profile

Parameter
NSF_Buffer_Pool_Size
Syntax
NSF_Buffer_Pool_Size=number of bytes
Category
Performance / Memory (cache)
Component
Server and client (per HCL: applies on both servers and workstations, with different maximum values)
Available since
At least 9.0.1 (HCL documentation)
Supported versions
9.0.1, 11.0(.1), 14.0 — directly substantiated by HCL doc states
GUI equivalent
According to HCL None — no GUI equivalent.
Default value
Automatically determined (see description)
Possible values
Integer in bytes
Related parameter
NSF_Buffer_Pool_Size_MB (same setting in megabytes)

Description

According to HCL product documentation, NSF_Buffer_Pool_Size sets the maximum size (in bytes) of the NSF buffer pool — a memory area used for buffering I/O transfers between Domino and disk storage.
Default value (verbatim from HCL product docs):
  • Automatically determined by the server or workstation. HCL explicitly recommends accepting the automatically determined value, except on partitioned servers. The more memory available, the larger the default the server sets.
  • On workstations: maximum setting NSF_Buffer_Pool_Size = 8 MB (on Mac: 4 MB).
  • On servers: default maximum between 1/8 and 3/8 of the available physical memory, depending on its total size.
  • On partitioned servers: defaults are not adjusted automatically. Here it is usually necessary to manually set the maximum values per partition such that the sum across all partitions amounts to roughly 1/4 to 3/8 of main memory.
The HCL tuning help page Improving database and Domino Directory performance adds: the value automatically calculated by default is usually sufficient; however, if database statistics indicate more memory is needed, the value should be increased a few megabytes at a time. The NSF_Buffer_Pool_Size_MB parameter also exists, which makes the same setting in megabytes.

Example configuration

NSF_Buffer_Pool_Size_MB=2048
The example shows the MB variant of the parameter — in practice, it is more readable for manual configuration than the byte variant. (HCL provides both variants on equal footing.)

Notes & pitfalls

  • HCL expressly recommends accepting the default, except on partitioned servers.
  • Per HCL, too large a value can lead to excessive swapping/paging — performance monitoring is advisable.
  • NSF_Buffer_Pool_Size is set in bytes; NSF_Buffer_Pool_Size_MB in megabytes. Both parameters control the same pool.
  • 2 GB limit (per HCL 14.5.1 docs): Since NOTES.INI variables are signed integers, NSF_Buffer_Pool_Size is limited to a maximum of 2 GB. For larger pools, NSF_Buffer_Pool_Size_MB must be used.
  • Minimum size: Per HCL, the minimum size is 4 MB.
  • According to HCL, no GUI equivalent exists (UI equivalent: None).

Sources (HCL Product Documentation)