Start/notes.ini Parameters/DBMT_COMPACT_THREADS

DBMT_COMPACT_THREADS

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Parameter: DBMT_COMPACT_THREADS
Short description: Number of parallel Compact threads that the Database Maintenance Tool (dbmt) starts during a maintenance run.

Profile

Parameter
DBMT_COMPACT_THREADS
Category
Performance / Memory
Component
Server
Available since
10.0
Supported versions
10.0, 11.0, 12.0, 14.0, 14.5, 14.5.1
GUI equivalent
notes.ini only (no GUI)
Possible values
Integer (default 2; typically 1–16, never higher than CPU cores)

Description

On modern Domino servers, the Database Maintenance Tool (dbmt) replaces the classic mix of Compact, Updall, and Fixup and is triggered once a night via a Program document. DBMT_COMPACT_THREADS defines how many Compact operations dbmt runs in parallel.
On modern multi-core servers, values between 4 and 8 are typical – values that are too high cause context-switch overhead on I/O-bound storage without saving any wall-clock time.

Example configuration

DBMT_COMPACT_THREADS=4

Notes & pitfalls

  • Never set higher than the available physical cores.
  • On I/O-bound storage (HDD, slow SAN), parallelism brings little benefit.
  • Complementary to Compact_Max_Threads, DBMT_FILTER, Update_*.
  • On memory-constrained servers, scale up cautiously – each Compact instance allocates its own memory.
  • Takes effect with the next dbmt invocation; a server restart is not strictly required.