Start/notes.ini Parameters/Server_MaxPossibleTransTime

Server_MaxPossibleTransTime

Parameter: Server_MaxPossibleTransTime
Short description: Upper bound (in microseconds) for a single transaction in the Server Availability Index (SAI/LoadMon) calculation. Transactions that take longer are capped at this value. Together with Server_MinPossibleTransTime, it prevents extremely long single transactions from skewing the SAI.

Profile

Parameter
Server_MaxPossibleTransTime
Syntax
Server_MaxPossibleTransTime=<µs>
Value
Integer in microseconds
Default
Domino-internal default; in practice recommended: 20000000 (= 20 s)
Scope
Domino server (LoadMon / Server Availability Index)
Category
Performance / Memory (SAI tuning)
GUI equivalent
None (notes.ini only)
Related
Server_MinPossibleTransTime, Server_TransInfo_Max, Server_TransInfo_Update_Interval, Server_Min_Trans, Server_Availability_Threshold
Available since
Domino 8.5 (originally SPR in 7.0.4)

Description

  • The LoadMon task calculates the Server Availability Index (SAI) from real transaction times. Very short transactions push the value up, very long single transactions pull it down dramatically.
  • Server_MaxPossibleTransTime sets an upper bound: any transaction taking longer than the configured value is capped at exactly this value for the SAI calculation.
  • Together with Server_MinPossibleTransTime (lower bound), this defines a corridor in which the SAI calculation is less susceptible to outliers.
  • Values must be specified in microseconds:
    • 1000 = 1 ms
    • 1500 = 1.5 ms (typical Min value in the HCL/Nashed recommendation for Server_MinPossibleTransTime)
    • 20000000 = 20 s (typical Max value for Server_MaxPossibleTransTime)
  • Recommended in particular on:
    • fast servers whose SAI otherwise stays low despite good hardware,
    • virtualized servers (VM), where occasional IO spikes skew the SAI.
  • After changing the values, loadmon.ncf should be deleted while the server is shut down so that old min/max values are discarded.

Example

Typical SAI tuning configuration:
Server_MinPossibleTransTime=1500
Server_MaxPossibleTransTime=20000000
  • Lower bound 1.5 ms, upper bound 20 s for all transactions considered in the SAI calculation.

Notes

  • Change requires a server restart; before that, it is advisable to delete loadmon.ncf from the data directory.
  • After restart, check effect under load with show ai and show stat server.expansionfactor.
  • Companion parameters for finer tuning: Server_TransInfo_Max, Server_TransInfo_Update_Interval, Server_Min_Trans, debug_loadmon=1 (for diagnostics).
  • Works on all supported platforms.
  • HCL has so far not published a dedicated entry for this parameter on help.hcl-software.com. The values and behavior, however, are consistently documented through HCL-internal forum documents (ds_infolib.hcltechsw.com), the official AdminCamp PDF, and the blog maintained by HCL employee Daniel Nashed.

Sources