Problem

Migration from 3.1.3 to 3.2.x

Same flows without an issue before the migration

Several abend per day

Large file transfers > 4 GB

CFTOUT:

CEE3201S The system detected an operation exception (System Completion Code=0C1).
From compile unit SISYLEWA at entry point SISYLEWA at compile unit offset +00000302 at entry offset +00000302 at address
1D75228A

Resolution

Starting from version 3.2.x transfers optimization has been introduced.

One of the change done, to avoid delay when dealing with data acknowledgement, was to deal asynchronously in between the cache (hyperspace) and the physical catalog record.

It makes very fast operation for the ACK operations but it also makes use of extra counters for the delayed operations.

The not optimized protocol parameters along with a large file transfer on a fast network gets CFT failing with more than 100 000 checkpoints buffered.

All samples provided are set with accurate and right sized parameters for performances but for existing customers, values are issues from the migration.

It was working in previous versions but with lowered performances introduced by the high number of sync points that were synchronously written to the Transfer CFT catalog.

Solution:

Update S/RPACING to a higher value.
Update S/RRUSIZE to a higher value, it can be upsized to 32750 (verify first that the TCP send and receive buffers are already set to a larger value, existing values are available from a 'netstat config')

Attention, the Checkpoints and xRUSIZE and negotiated parameters with the partner.

• Therefore, you need to check the negotiated values before applying a change in order to identify if the partner has to be involved or not.
• The log message CFTH56I is displaying the negotiated value, it is also available from a CFTUTIL LISTCAT CONTENT=DEBUG done on a completed transfer.