Determine #sessions to set for load / exp jobs

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KN
Enthusiast

Determine #sessions to set for load / exp jobs

Hello Gurus

Is there a rule of thumb that one should follow for determining the number sessions that should be set for a load or fexp jobs?

Suppose if my system is a 4 node system with 40amps/node , what would be the best practice?

regards

KN

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5 REPLIES
Teradata Employee

Re: Determine #sessions to set for load / exp jobs

The calculation that is often used in TASM (TDWM, workload management) is:

If number of AMPs <= 20, then use 1 per AMP.

If number of AMP > 20, then use 20 + (#AMPS/20)

But that number can change based on the size of the job (amount of data to be loaded):

The above calculations are for "medium" jobs.

For "Large" jobs, multiply the session number for "medium" by 1.50.

For "small" jobs, multiple the session number for "medium" by .50.

-- SteveF
Teradata Employee

Re: Determine #sessions to set for load / exp jobs

Better yet, let WLM manage the number of sessions and only change the ones that really need exceptions via WLM rules. 

KN
Enthusiast

Re: Determine #sessions to set for load / exp jobs

Thank you... Todd and Steve..

In our Tasm the no of session set for for default,large and small fexp jobs have been set to 4 ,4 & 2 respectively..

TASM will not auto calculate the no of sessions unless we put in the no of sessions . is my understanding correct?. Given Steve's formula it looks like i  will definitly have to increase a TASM session limits to a higher number.. If a user uses a queryband utilitiy session to small for loading a large file then the no of sessions allocated would be only 2 in our case and performance would be low.

thanks

KN

Teradata Employee

Re: Determine #sessions to set for load / exp jobs

Steve's comment related to LOAD sessions. For EXPORT, the defaults (4, 4, 2) are generally fine. I would not change them.

Not sure what you mean by "not auto calculating". The WLM defaults are defined when the system is initialized. Load utilities default to use as many sessions as possible (and WLM controls the upper limit).

KN
Enthusiast

Re: Determine #sessions to set for load / exp jobs

Fred

i thought the general calculation applies to the FEXP as well... Just wanted to understand if i have 2 seperate System across continents and if a Business( based in Aus ) is trying to pull medium volume of data from a TD system based out of UK, dont you think the no of sessions defined ( 4,4,2) will slow the data movement..

Just trying to see how i can accomodate such situations...

thanks

KN