WASPreUpgrade + WASPostUpgrade take days to run when processing large files

WASPreUpgrade and WASPostUpgrade allows a migration between two WAS versions, e.g. 8.0 to 9.0 or 8.5 to 9.0. The WASPreUpgrade process effectively exports the data from the original profile. The WASPostUpgrade effectively imports the data from the profile. In some situations, the WASPostUpgrade task will modify some of the data imported. In other situations, it makes no modifications to the data.

If a profile contains a large file, both WASPreUpgrade and WASPostUpgrade processes will continue to run, however, they may take days to complete successfully. The WASPostUpgrade process in particular appears to be the slower of the two processes. This can be reproduced by leaving large files - e.g. a core dump, trace files, sizable .ear applications - etc. in a profile during the WASPostUpgrade process.

A local fix for this issue is documented in an IBM APAR that was closed "SUG", or suggestion, not implemented in the code:

https://www.ibm.com/support/pages/apar/PI96903

"Local fix

Remove any large files that should not be present in the

WebSphere file system

"

Further commentary - this is not an issue related to the underlying hardware speed. Adding more disk IOPS will not help here, this is purely an issue with the code in use. Manually copying the large file on the filesystem outside of the WASPostUpgrade code takes one minute at most, versus days within the WASPostUpgrade code.