Pathway/iTS System Management Manual (G06.24+)

Tuning Your System Using Statistics
HP NonStop Pathway/iTS System Management Manual—426748-002
5-11
POOL INFO
•
MAX-TPS
indicates the maximum number of transactions per second (the peak transaction
rate). You can determine MAX-TPS in several ways. For example:
•
You can code your application to record this information.
•
You can estimate this information by counting the number of SEND statements
to a server class (where the server class has a fixed relationship to a
transaction).
To determine the number of SEND statements to a server class, analyze the
server statistics for I/O INFO. REQ CNT indicates the total number of SEND
statements to servers in a server class.
If you do not know the maximum transaction rate, use an estimate of 1.5 to 5 times
the average transaction rate.
To determine the average transaction rate, you can use the Measure product or
specify the STATS SERVER, INTERVAL SECS command and use the display
information (I/O COUNT). You can use this formula:
AVGTXRATE = IO-COUNT / SECONDS
•
EST-RESP-TIME
indicates the estimated time, in seconds, that a transaction takes to complete.
To determine the estimated response time for a transaction, analyze the response
time statistics for both the terminal and server involved in the transaction. By
adding these response times, you can estimate the response time for a
transaction.
•
SAFETY-FACTOR
provides a safety factor to your formula. As a precaution, SAFETY-FACTOR
increases the size of SERVERPOOL a little more than you think is needed. As a
general guideline, you can specify a value from 1.1 to 1.4 for the safety factor.
At any time, the maximum value that you should specify for SERVERPOOL is:
SERVERPOOL = MAXTERMS * MAXREPLY
To determine the current values for MAXTERMS and MAXREPLY, use the INFO TCP
command.
To adjust the size of SERVERPOOL, use the STATS TCP display information (MAX
ALLOC) to determine the appropriate size.
REQ CNT
For both SERVERPOOL and TERMPOOL, REQ CNT indicates the physical number of
requests for buffer allocation. Some DISPLAY and ACCEPT operations require
multiple physical I/O operations; consequently, there is a one-to-many relationship
between these statements and pool allocation. SEND statements always require only
one I/O operation; consequently, there is a one-to-one relationship between SEND
statements and pool allocation.