Report Burst Failure

[Bindiya]

Hello Everyone.,
We have a report that is set to burst to generate around 650 PDFs on to file system every month. This is a complex report and presents data from Teradata and DB2 tables.
We have upgraded to 10.2.2 last month and since then burst process fails after generating around 300 outputs. In 10.1, burst process used to happen sequentially which is changed to parallel in 10.2 by default.
10.1 – Sequential – Burst succeeds – Takes 4.20 hrs
10.2 – Sequential – Burst succeeds – Takes 7 hrs
10.2 – Parallel – Burst Fails – Takes ~2.15 hrs (when tested in DEV)
Since there is a lot of performance hit by changing it to sequential, we don't want to go for it although it does not fail.
Moreover, the parallel burst in 10.2 did not fail in DEV. It fails only in PROD with below error.
Error:

Code Select Expand

QE-DEF-0285 The logon failed. QE-DEF-0321 The userID or password is either missing or invalid. RQP-DEF-0068 Unable to connect to at least one database during a multi-database attach to 2 database(s) in: COGNOS_DS_V COGNOS_DS_MXV UDA-SQL-0031 Unable to access the "COGNOS_DS_V" database. Check that the connection parameters to the database are configured correctly. For example, ensure that the data source connection contains the signon information, such as a password, to connect to the database. UDA-SQL-0129 Invalid login information was detected by the underlying database. [Teradata][ODBC Teradata Driver][Teradata Database] All virtual circuits are currently in use. [Teradata][ODBC Teradata Driver] Not enough information to log on

Although error starts with "Logon Failed" it might not be related to any such issues because, it successfully generated few outputs. Our DBA thought "All virtual circuits are currently in use" in the error message might be the reason or failure because the number of sessions it is using on Teradata has reached the max limit 480 (we have 2 servers with 2 nodes on each and 120 sessions on each node).
In Dev it never crossed 250, though Teradata capacity is more there.

How to know why Cognos created so many sessions on Teradata? Is there any parameter where it could be set?
Appreciate any suggestions on this.
Thank you.

[bdbits]

Since it works sequentially, I would guess enabling parallel may mean it will open a separate session for each burst.

The way to confirm that would be to ask Cognos support.

[Bindiya]

Ok, we will do that. Thanks for looking into it though.

[Bindiya]

Similar issue is listed in FP2. Its opening multiple sessions for us and when we look into the queries most, of them are HELP queries. Even in DEV, although it is not exceeding 250 sessions, most of the queries in those sessions are HELP.
http://www-01.ibm.com/support/docview.wss?uid=swg1PI13343
So, probably if we apply the fix pack it will cut the queries down and bring the session count down too.