TMF Planning and Configuration Guide (H06.05+)

Reconfiguring Transaction Limits
HP NonStop TMF Planning and Configuration Guide—540136-002
4-3
Active Transactions in the System
using the ALTER BEGINTRANS command. Only members of the super group can
issue ALTER BEGINTRANS commands.
Active Transactions in the System
The TRANSCOUNTTHRESH limit controls the total number of active transactions in
the HP NonStop server at any given time.
The limit consists of an upper and a lower threshold value. When the total transaction
count reaches the upper threshold, new transactions are disabled. When the
transaction count falls below the lower threshold, new transactions are reenabled,
provided all other conditions for reenabling exist. The upper threshold must be greater
than the lower threshold.
The transaction count threshold is necessary because without it, tables internal to TMF
could become filled, thereby causing the transaction management process (TMP) to
fail and all TMF operations to stop abruptly.
The default values are:
Upper threshold = 1600
Lower threshold = 1500
If you change these limit values, the changes take effect immediately.
It is recommended that you set the values so that there is a large range (such as 100)
between the disable and reenable limits. Doing so helps to prevent transaction
processing from switching frequently between the enabled and disabled states.
Active Transactions in a Processor
The TRANSPERCPU limit controls the total number of active transactions in a
processor at any given time. It consists of two values. The first applies to processors
in which the transaction management process (TMP) does not run; the second applies
to processors in which the TMP runs.
The value for non-TMP processors determines the number of transactions that can be
started concurrently in a processor where the TMP does not run. The value for TMP
processors determines the number that can be started in processors where the TMP
runs.
When the total transaction count within a processor reaches the configured limit, new
transactions are not allowed to begin within that processor. When the transaction
count returns below the limit, new transactions are once again permitted to begin within
the processor.
The default for both limit values is 1024. Each value must be a power of 2.
Caution. If the starting of new transactions is disabled, applications could abort unless they
have been coded to handle that situation.